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<P CLASS="western" STYLE="margin-bottom: 0in"><FONT SIZE=4 STYLE="font-size: 15pt"><B>Task
Scheduler</B></FONT></P>
<P CLASS="western" STYLE="margin-bottom: 0in"><B>Cooperative
multitasking for Arduino microcontrollers</B></P>
<P CLASS="western" STYLE="margin-bottom: 0in; border-top: none; border-bottom: 1px solid #000000; border-left: none; border-right: none; padding-top: 0in; padding-bottom: 0.01in; padding-left: 0in; padding-right: 0in">
<FONT SIZE=2 STYLE="font-size: 11pt"><B>Version 2.0.0: 2015-12-23</B></FONT></P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><B>OVERVIEW</B>:</P>
<P CLASS="western" STYLE="margin-bottom: 0in">A lightweight
implementation of cooperative multitasking (task scheduling)
supporting:</P>
<OL>
<LI><P CLASS="western" STYLE="margin-bottom: 0in">Periodic task
execution (with dynamic execution period in milliseconds –
frequency of execution)</P>
<LI><P CLASS="western" STYLE="margin-bottom: 0in">Number of
iterations (limited or infinite number of iterations)</P>
<LI><P CLASS="western" STYLE="margin-bottom: 0in">Execution of tasks
in predefined sequence</P>
<LI><P CLASS="western" STYLE="margin-bottom: 0in">Dynamic change of
task execution parameters (frequency, number of iterations, callback
methods)</P>
<LI><P CLASS="western" STYLE="margin-bottom: 0in">Power saving via
entering IDLE sleep mode when tasks are not scheduled to run</P>
<LI><P CLASS="western" STYLE="margin-bottom: 0in">Support for
event-driven task invocation via Status Request object</P>
<LI><P CLASS="western" STYLE="margin-bottom: 0in">Support for task
IDs and Control Points for error handling and watchdog timer</P>
<LI><P CLASS="western" STYLE="margin-bottom: 0in">Support for Local
Task Storage pointer (allowing use of same callback code for
multiple tasks)</P>
<LI><P CLASS="western" STYLE="margin-bottom: 0in">Support for
layered task prioritization</P>
</OL>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in">Scheduling overhead:
between 15 and 18 microseconds per scheduling pass.</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><B>TASK</B>:</P>
<P CLASS="western" STYLE="margin-bottom: 0in">“Task” is a
container concept that links together:</P>
<OL>
<LI><P CLASS="western" STYLE="margin-bottom: 0in">Program code
performing specific task activities (callback methods)</P>
<LI><P CLASS="western" STYLE="margin-bottom: 0in">Execution interval</P>
<LI><P CLASS="western" STYLE="margin-bottom: 0in">Number of
execution iterations</P>
<LI><P CLASS="western" STYLE="margin-bottom: 0in">(Optionally)
Execution event (Status Request)</P>
<LI><P CLASS="western" STYLE="margin-bottom: 0in">(Optionally)
Pointer to a Local Task Storage area</P>
</OL>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><B>Tasks</B> perform
certain functions, which could require periodic or one-time
execution, update of specific variables, or waiting for specific
events. Tasks also could be controlling specific hardware, or
triggered by hardware interrupts.
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in">For execution purposes
<B>Tasks</B> are linked into execution <B>chains</B>, which are
processed by the <B>Scheduler</B> in the order they were added
(linked together).</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><B>Starting with
version 2.0.0 TaskScheduler supports task prioritization. Please
refer to the specific chapter of this manual for details on layered
prioritization. </B>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in">Each task performs its
function via a callback method. Scheduler calls Task’s callback
method periodically until task is disabled or runs out of iterations.
In addition to “regular” callback method, two additional methods
could be utilized for each task: a callback method invoked every time
the task is enabled, and a callback method invoked once when the task
is disabled. Those two special methods allow tasks to properly
initiate themselves for execution, and clean-up after execution is
over (E.g., setup pin modes on enable, and always bring pin level to
LOW at the end).
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in">Tasks are responsible
for supporting <B>cooperative</B> <B>multitasking</B> by being “good
neighbors”, i.e., running their callback methods quickly in a
non-blocking way, and releasing control back to scheduler as soon as
possible.
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><B>Scheduler</B> is
executing Tasks' callback methods in the order the tasks were added
to the chain, from first to last. Scheduler stops and exists after
processing the chain once in order to allow other statements in the
main code of <B>loop()</B> method to run. This is referred to as a
<B>“scheduling pass”.</B></P>
<P CLASS="western" STYLE="margin-bottom: 0in">(Normally, there is no
need to have any other statements in the <B>loop</B>() method other
than the Scheduler's <B>execute</B>() method).</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in; page-break-after: avoid">
<B>Below is the flowchart of a Task lifecycle:</B></P>
<P CLASS="western" STYLE="margin-bottom: 0in"><IMG SRC="TaskScheduler_html.png" NAME="graphics1" ALIGN=BOTTOM WIDTH=664 HEIGHT=517 BORDER=0></P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><B>TaskScheduler</B>
library maybe compiled with different compilation controls
enabled/disabled. This is a way to limit TaskScheduler functionality
(and size) for specific purpose (sketch). This is achieved by
defining specific #<B>define</B> parameters <I>before</I>
TaskScheduler.h header file. Specifically:</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in">If compiled with
<FONT FACE="Courier New, monospace">_TASK_SLEEP_ON_IDLE_RUN</FONT>
enabled, the scheduler will place processor into IDLE sleep mode (for
approximately 1 ms, as the timer interrupt will wake it up), after
what is determined to be an “idle” pass. An Idle Pass is a pass
through the task chain when no Tasks were scheduled to run their
callback methods. This is done to avoid repetitive idle passes
through the chain when no tasks need to be executed. If any of the
tasks in the chain always requires immediate execution (aInterval =
0), then there will be no IDLE sleep between task's callback method
execution.</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><B>NOTE: </B>Task
Scheduler uses <B>millis()</B> to determine if tasks are ready to be
invoked. Therefore, if you put your device to any “deep” sleep
mode disabling timer interrupts, the <B>millis()</B> count will be
suspended, leading to effective suspension of scheduling. Upon wake
up, active tasks need to be re-enabled, which will effectively reset
their internal time scheduling variables to the new value of
<B>millis(). </B>Time spent in deep sleep mode should be considered
“frozen”, i.e., if a task was scheduled to run in 1 second from
now, and device was put to sleep for 5 minutes, upon wake up, the
task will still be scheduled 1 second from the time of wake up.
Executing <B>enable() </B>method on this tasks will make it run as
soon as possible. This is a concern only for tasks which are required
to run in a truly periodical manner (in absolute time terms).
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in">In addition to
time-only (<B>millis</B>() only) invocation, tasks can be scheduled
to wait on an event employing StatusRequest objects (more about
Status Requests later).</P>
<P CLASS="western" STYLE="margin-bottom: 0in">Consider a scenario
when one task (t1) is performing a function which affects execution
of many tasks (t2, t3). In this case the task t1 will “signal”
completion of its function via Status Request object. Tasks t2 and t3
are “waiting” on the same Status Request object. As soon as
status request completes, t2 and t3 are activated.</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in">Alternative scenario is
the ne task (t1) and waiting for the completion of a number of tasks
(t2, t3). When done, t2 and t3 signal completion of their functions,
t1 is invoked.
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in">Please see the code
examples at the end of this document, and included with the library
package for details.</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><B>COMPILE PARAMETERS:</B></P>
<P CLASS="western" STYLE="margin-bottom: 0in">This library could be
compiled in several configurations.</P>
<P CLASS="western" STYLE="margin-bottom: 0in">Parameters (<B>#define</B>s)
defining what functionality should or should not be included need be
defined before the library header file in the body of arduino sketch.</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in">#define
<B>_TASK_TIMECRITICAL</B></P>
<P CLASS="western" STYLE="margin-bottom: 0in">...will compile the
library with time critical tracking option enabled.</P>
<P CLASS="western" STYLE="margin-bottom: 0in">Time critical option
keeps track when current execution took place relative to when it was
scheduled, and where next execution time of the task falls. Two
methods provide this information.
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><B>Task::getStartDelay()
</B>method: return number of milliseconds between current system time
(millis) and point in time when the task was scheduled to start. A
value of 0 (zero) indicates that task started right on time per
schedule.
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><B>Task::getOverrun()</B>
method: If <B>getOverrun </B>returns a negative value, this Task’s
next execution time point is <I>already</I> in the past, and task is
behind schedule. This most probably means that either task’s
callback method's runtime is too long, or the execution interval is
too short (and therefore schedule is too aggressive).</P>
<P CLASS="western" STYLE="margin-bottom: 0in">A positive value
indicates that task is on schedule, and callback methods have enough
time to finish before the next scheduled pass.
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in">#define
<B>_TASK_SLEEP_ON_IDLE_RUN</B></P>
<P CLASS="western" STYLE="margin-bottom: 0in">...will compile the
library with the <B>sleep</B> option enabled (AVR boards only).</P>
<P CLASS="western" STYLE="margin-bottom: 0in">When enabled, scheduler
will put the microcontroller into <B>SLEEP_MODE_IDLE</B> state if
none of the tasks’ callback methods were activated during execution
pass. <B>IDLE</B> state is interrupted by timers once every 1 ms.
Putting microcontroller to IDLE state helps conserve power. Device
in SLEEP_MODE_IDLE wakes up to all hardware and timer interrupts, so
scheduling is kept current.</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in; page-break-after: avoid">
#define <B>_TASK_STATUS_REQUEST</B></P>
<P CLASS="western" STYLE="margin-bottom: 0in">…will compile
TaskScheduler with support for StatusRequest object. Status Requests
are objects allowing tasks to wait on an event, and signal event
completion to each other.
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in">#define <B>_TASK_WDT_IDS</B></P>
<P CLASS="western" STYLE="margin-bottom: 0in">…will compile
TaskScheduler with support for Task IDs and Control Points. Each task
can be (and is by default) assigned an ID, which could be used to
identify the task in case there is a problem with it. Furthermore
within the task, Control Points could be defined to further help with
pinpointing potential problem areas. For instance, the tasks which
deal with external resources (sensors, serial communications,
anything hardware dependent) can be blocked (or hung), by failed
hardware. In this case, a watchdog timer could be employed to trap
such a failed task, and identify which one (by task id) and where in
the task (by a control point) the problem is likely located.</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><B>NOTE: </B>by
default, talk IDs are assigned sequentially (1, 2, 3, …) to the
tasks as they are being created. Programmer can assign a specific
task id. <B>Task ids are unsigned integers.</B></P>
<P CLASS="western" STYLE="margin-bottom: 0in">Control points provide
a way to identify potential problem points within a task. Control
points are <B>unsigned integers </B>as well. Please note that there
is only one control point per task, and it is set to zero when the
task’s callback method is invoked (this is done to prevent “stray”
control point from previous task(s) confusing the matters.</P>
<P CLASS="western" STYLE="margin-bottom: 0in">Example #7 contains a
test of task ID and control points functionality.
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in">#define
<B>_TASK_LTS_POINTER</B></P>
<P CLASS="western" STYLE="margin-bottom: 0in">…will compile
TaskScheduler with support for Local Task Storage pointer (LTS). LTS
is a generic (void*) pointer which could be set to reference a
variable or a structure specific to a particular task. A callback
method can get access to specific variables by getting reference to a
currently running task from the scheduler, and then casting (void*)
LTS pointer to the appropriate pointer type.
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><B>NOTE: </B>above
parameters are<B> DISABLED </B>by default, and need to be explicitly
enabled by placing appropriate #define statements in front of the
#include statement for the TaskScheduler header file.</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in">#define <B>_TASK_PRIORITY</B></P>
<P CLASS="western" STYLE="margin-bottom: 0in">…will compile
TaskScheduler with support for layered task prioritization. Task
prioritization is achieved by creating several schedulers, and
organizing them in priority layers. Tasks are assigned to schedulers
corresponding to their priority. Tasks assigned to the “higher”
layers are evaluated for invocation more frequently, and are given
priority in execution in case of the scheduling coincidence. More
about layered prioritization in the API documentation and
TaskScheduler examples.
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><B>TASK PRIORITY AND
COOPERATIVE MULTITASKING:</B></P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in">Starting with version
2.0.0 TaskScheduler supports task prioritization. Priority is
associated with a <B>Scheduler</B>, not individual <B>Tasks</B>,
hence the concept of priority layers. Tasks subsequently are assigned
to schedulers corresponding to their desired priority. The lowest
priority Scheduler is called “<B>base scheduler</B>” or “<B>base
layer</B>”. Let’s call higher priority schedulers by their
priority number, with larger number corresponding to higher priority
of task execution.
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in">Task prioritization is
achieved by executing the entire chain of tasks of the higher
priority scheduler for every single step (task) of the lower priority
chain. <B>Note</B> that actual callback method invocation depends on
priority <B>and </B>the timing of task schedule. However, higher
priority tasks are evaluated more frequently and are given priority
in case of scheduling collision.
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in">For most tasks
TaskScheduler <B>does not need </B>task priority functionality.
Prioritization requires additional scheduling overhead, and should be
used only for critical tasks.</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in">A few points on that:</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in">1. Plain (non-layered)
execution chain is simple and efficient. The main idea is to minimize
scheduling overhead by Scheduler going through the chain. Each
priority layer adds scheduling overhead to overall task chain
execution. Let’s review 3 scenarios:</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><B>I.
Flat chain of 7 tasks:</B></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">Scheduling
evaluation sequence:</P>
<P CLASS="western" ALIGN=CENTER STYLE="margin-left: 0.49in; margin-bottom: 0in">
1 <FONT FACE="Wingdings"></FONT> 2 <FONT FACE="Wingdings"></FONT>
3 <FONT FACE="Wingdings"></FONT> 4 <FONT FACE="Wingdings"></FONT>
5 <FONT FACE="Wingdings"></FONT> 6 <FONT FACE="Wingdings"></FONT>
7</P>
<P CLASS="western" ALIGN=CENTER STYLE="margin-left: 0.49in; margin-bottom: 0in">
<BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">Scheduling
overhead:</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">O
= B * T = 7 * 18 = 126 microseconds,</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">Where:</P>
<P CLASS="western" STYLE="margin-left: 0.98in; margin-bottom: 0in">O
– scheduling overhead</P>
<P CLASS="western" STYLE="margin-left: 0.98in; margin-bottom: 0in">B
– number of tasks in the base layer</P>
<P CLASS="western" STYLE="margin-left: 0.98in; margin-bottom: 0in">T
– scheduling overhead of a single task execution evaluation
(currently with Arduino Uno running at 16 Mhz is between 15 and 18
microseconds).</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><B>II.
Two priority layers of 7 tasks. </B>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><B> </B>Tasks
1, 2, 3, 4, 5 are base priority and 6, 7 are higher priority:</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">Scheduling
evaluation sequence:</P>
<P CLASS="western" ALIGN=CENTER STYLE="margin-left: 0.49in; margin-bottom: 0in">
6 <FONT FACE="Wingdings"></FONT> 7 <FONT FACE="Wingdings"></FONT>
1 <FONT FACE="Wingdings"></FONT> 6 <FONT FACE="Wingdings"></FONT>
7 <FONT FACE="Wingdings"></FONT> 2 <FONT FACE="Wingdings"></FONT>
6 <FONT FACE="Wingdings"></FONT> 7 <FONT FACE="Wingdings"></FONT>
3 <FONT FACE="Wingdings"></FONT> 6 <FONT FACE="Wingdings"></FONT>
7 <FONT FACE="Wingdings"></FONT> 4 <FONT FACE="Wingdings"></FONT>
6 <FONT FACE="Wingdings"></FONT> 7 <FONT FACE="Wingdings"></FONT>
5</P>
<P CLASS="western" ALIGN=CENTER STYLE="margin-left: 0.49in; margin-bottom: 0in">
<BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">Scheduling
overhead:</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">O
= (B + B * P1) * T = (5 + 5 * 2) * 18 = 270 microseconds,</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">Where:</P>
<P CLASS="western" STYLE="margin-left: 0.98in; margin-bottom: 0in">O
– scheduling overhead</P>
<P CLASS="western" STYLE="margin-left: 0.98in; margin-bottom: 0in">B
– number of tasks in the base layer</P>
<P CLASS="western" STYLE="margin-left: 0.98in; margin-bottom: 0in">P1
– number of tasks in the priority 1 layer</P>
<P CLASS="western" STYLE="margin-left: 0.98in; margin-bottom: 0in">T
– scheduling overhead of a single task execution evaluation
(currently with Arduino Uno running at 16 Mhz is between 15 and 18
microseconds).</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><B>III.
Three priority layers of 7 tasks. </B>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><B> </B>Tasks
1, 2, 3, are base priority, 4, 5 are priority 1, and 6, 7 are
priority 2:</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">Scheduling
evaluation sequence:</P>
<P CLASS="western" ALIGN=CENTER STYLE="margin-left: 0.49in; margin-bottom: 0in">
6 <FONT FACE="Wingdings"></FONT> 7 <FONT FACE="Wingdings"></FONT>
4 <FONT FACE="Wingdings"></FONT> 6 <FONT FACE="Wingdings"></FONT>
7 <FONT FACE="Wingdings"></FONT> 5 <FONT FACE="Wingdings"></FONT>
1 <FONT FACE="Wingdings"></FONT> 6 <FONT FACE="Wingdings"></FONT>
7 <FONT FACE="Wingdings"></FONT> 4 <FONT FACE="Wingdings"></FONT>
6 <FONT FACE="Wingdings"></FONT> 7 <FONT FACE="Wingdings"></FONT>
5 <FONT FACE="Wingdings"></FONT> 2 <FONT FACE="Wingdings"></FONT>6
<FONT FACE="Wingdings"></FONT> 7 <FONT FACE="Wingdings"></FONT>
4 <FONT FACE="Wingdings"></FONT> 6 <FONT FACE="Wingdings"></FONT>
7 <FONT FACE="Wingdings"></FONT> 5 <FONT FACE="Wingdings"></FONT>
3
</P>
<P CLASS="western" ALIGN=CENTER STYLE="margin-left: 0.49in; margin-bottom: 0in">
<BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">Scheduling
overhead:</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">O
= (B + B * P1 + B * P1 * P2) * T = (3 + 3 * 2 + 3 * 2 * 2) * 18 = 378
microseconds,</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">Where:</P>
<P CLASS="western" STYLE="margin-left: 0.98in; margin-bottom: 0in">O
– scheduling overhead</P>
<P CLASS="western" STYLE="margin-left: 0.98in; margin-bottom: 0in">B
– number of tasks in the base layer</P>
<P CLASS="western" STYLE="margin-left: 0.98in; margin-bottom: 0in">P1
– number of tasks in the priority 1 layer</P>
<P CLASS="western" STYLE="margin-left: 0.98in; margin-bottom: 0in">P2
– number of tasks in the priority 2 layer</P>
<P CLASS="western" STYLE="margin-left: 0.98in; margin-bottom: 0in">T
– scheduling overhead of a single task execution evaluation
(currently with Arduino Uno running at 16 Mhz is between 15 and 18
microseconds).</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in">Scheduling overhead of
a 3 layer prioritization approach is 3 times higher than that of a
flat execution chain. <B>Do</B> evaluate if task prioritization is
really required for your sketch.</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in">2. TaskScheduler is <B>NOT</B>
a pre-emptive multi-tasking library. Nor is it a Real-Time OS. There
is no way to break execution of one task in favor of another.
Therefore callback methods require careful programming for
cooperative behavior.</P>
<P CLASS="western" STYLE="margin-bottom: 0in">This has, however,
significant benefits: you don't need to worry about concurrency
inside the callback method, since only one callback method runs at a
time, and could not be interrupted. All resources are yours for that
period of time, no one can switch the value of variables (except
interrupt functions of course...), etc. It is a stable and
predictable environment, and it helps a lot with writing stable code.
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in">A number of things
could be done instead of priorities:</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in">1. Schedule your
critical tasks to run more frequently than the other tasks</P>
<P CLASS="western" STYLE="margin-bottom: 0in">. <BR>(Since you can
control the interval, you could also change the task to run more or
less frequently as the situation demands).</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in">2. If one particular
callback routine is critical, create a couple of tasks referring to
the same callback and "sprinkle" them around the chain:</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"> <FONT FACE="FreeMono, MS Mincho, monospace"><FONT SIZE=2 STYLE="font-size: 10pt">Scheduler
ts;</FONT></FONT></P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"> <FONT FACE="FreeMono, MS Mincho, monospace"><FONT SIZE=2 STYLE="font-size: 10pt">Task
t1(20, TASK_FOREVER, &callback1, &ts);</FONT></FONT></P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"> <FONT FACE="FreeMono, MS Mincho, monospace"><FONT SIZE=2 STYLE="font-size: 10pt">Task
t2(1000, TASK_FOREVER, &callback2, &ts);</FONT></FONT></P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"> <FONT FACE="FreeMono, MS Mincho, monospace"><FONT SIZE=2 STYLE="font-size: 10pt">Task
t3(20, TASK_FOREVER, &callback1, &ts);</FONT></FONT></P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"> <FONT FACE="FreeMono, MS Mincho, monospace"><FONT SIZE=2 STYLE="font-size: 10pt">Task
t4(1000, TASK_FOREVER, &callback4, &ts);</FONT></FONT></P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"> <FONT FACE="FreeMono, MS Mincho, monospace"><FONT SIZE=2 STYLE="font-size: 10pt">t3.delay(10);</FONT></FONT></P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in">Note that t1 and t3
call the same callback method, and are shifted in time by 10 millis.
So effectively callback1 will be called every 10 millis, but would be
"sandwiched" between t2 and t4.
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in">3. Use short efficient
callback methods written for cooperative multitasking.</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in">What that means is:</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">a)
<B>DO NOT</B> use Arduino's <FONT FACE="FreeMono, MS Mincho, monospace"><FONT SIZE=2 STYLE="font-size: 10pt"><B>delay</B></FONT></FONT><FONT FACE="FreeMono, MS Mincho, monospace"><FONT SIZE=2 STYLE="font-size: 10pt">()</FONT></FONT><FONT FACE="Andale Mono, MS Mincho">
</FONT>function. It is blocking and will hold the entire chain.
Instead break the callback method into two, switch the callback
method of the task where delay is necessary and delay the task by
that number of millis. You get your delay, and other tasks get a
chance to run:</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">instead
of:</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="FreeMono, MS Mincho, monospace"><FONT SIZE=2 STYLE="font-size: 10pt">void
callback() {</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="FreeMono, MS Mincho, monospace"><FONT SIZE=2 STYLE="font-size: 10pt">...
stuff</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="FreeMono, MS Mincho, monospace"><FONT SIZE=2 STYLE="font-size: 10pt">delay(1000);</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="FreeMono, MS Mincho, monospace"><FONT SIZE=2 STYLE="font-size: 10pt">...
more stuff</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="FreeMono, MS Mincho, monospace"><FONT SIZE=2 STYLE="font-size: 10pt">}</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">do
this:</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="FreeMono, MS Mincho, monospace"><FONT SIZE=2 STYLE="font-size: 10pt">void
callback1() {</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="FreeMono, MS Mincho, monospace"><FONT SIZE=2 STYLE="font-size: 10pt">...
stuff</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="FreeMono, MS Mincho, monospace"><FONT SIZE=2 STYLE="font-size: 10pt">t1.setCallback(&callback2);</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="FreeMono, MS Mincho, monospace"><FONT SIZE=2 STYLE="font-size: 10pt">t1.delay(1000);</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="FreeMono, MS Mincho, monospace"><FONT SIZE=2 STYLE="font-size: 10pt">}</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="FreeMono, MS Mincho, monospace"><FONT SIZE=2 STYLE="font-size: 10pt">void
callback2() {</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="FreeMono, MS Mincho, monospace"><FONT SIZE=2 STYLE="font-size: 10pt">...
more stuff</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="FreeMono, MS Mincho, monospace"><FONT SIZE=2 STYLE="font-size: 10pt">t1.setCallback(&callback1);</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="FreeMono, MS Mincho, monospace"><FONT SIZE=2 STYLE="font-size: 10pt">}</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">b)
Same goes to <FONT FACE="FreeMono, MS Mincho, monospace"><FONT SIZE=2 STYLE="font-size: 10pt"><B>pulseIn</B></FONT></FONT><FONT FACE="FreeMono, MS Mincho, monospace"><FONT SIZE=2 STYLE="font-size: 10pt">()</FONT></FONT>
function. If you have to use it, set the timeout parameter such that
it is not a default 1 second. PulseIn functionality could be achieved
via pin interrupts, and that solution is non-blocking.</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">c)
Do don run long loops (for or do/while) in you callback methods. Make
the main arduino loop be the loop driver for you:</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">instead
of:</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="FreeMono, MS Mincho, monospace"><FONT SIZE=2 STYLE="font-size: 10pt">void
callback() {</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="FreeMono, MS Mincho, monospace"><FONT SIZE=2 STYLE="font-size: 10pt">for(int
i=0; i<1000; i++) {</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="FreeMono, MS Mincho, monospace"><FONT SIZE=2 STYLE="font-size: 10pt">...
stuff // one loop action</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="FreeMono, MS Mincho, monospace"><FONT SIZE=2 STYLE="font-size: 10pt">}</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="FreeMono, MS Mincho, monospace"><FONT SIZE=2 STYLE="font-size: 10pt">}</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">do
this:</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="FreeMono, MS Mincho, monospace"><FONT SIZE=2 STYLE="font-size: 10pt">Task
t1(TASK_IMMEDIATE, 1000, &callback);</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="FreeMono, MS Mincho, monospace"><FONT SIZE=2 STYLE="font-size: 10pt">void
callback() {</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="FreeMono, MS Mincho, monospace"><FONT SIZE=2 STYLE="font-size: 10pt">int
i = t1.getRunCounter() -1;</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="FreeMono, MS Mincho, monospace"><FONT SIZE=2 STYLE="font-size: 10pt">...
stuff // one loop action</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="FreeMono, MS Mincho, monospace"><FONT SIZE=2 STYLE="font-size: 10pt">}</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">or
this:</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="FreeMono, MS Mincho, monospace"><FONT SIZE=2 STYLE="font-size: 10pt">Task
t1(TASK_IMMEDIATE, 1000, &callback, true, &t1On);</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="FreeMono, MS Mincho, monospace"><FONT SIZE=2 STYLE="font-size: 10pt">int
i;</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="FreeMono, MS Mincho, monospace"><FONT SIZE=2 STYLE="font-size: 10pt">bool
t1On() {</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="FreeMono, MS Mincho, monospace"><FONT SIZE=2 STYLE="font-size: 10pt">i
= 0;</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="FreeMono, MS Mincho, monospace"><FONT SIZE=2 STYLE="font-size: 10pt">return
true;</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="FreeMono, MS Mincho, monospace"><FONT SIZE=2 STYLE="font-size: 10pt">}</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="FreeMono, MS Mincho, monospace"><FONT SIZE=2 STYLE="font-size: 10pt">void
callback() {</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="FreeMono, MS Mincho, monospace"><FONT SIZE=2 STYLE="font-size: 10pt">...
stuff // one loop action</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="FreeMono, MS Mincho, monospace"><FONT SIZE=2 STYLE="font-size: 10pt">i++;</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="FreeMono, MS Mincho, monospace"><FONT SIZE=2 STYLE="font-size: 10pt">}</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" ALIGN=CENTER STYLE="margin-left: 0.49in; margin-bottom: 0in">
<B>REMEMBER: you are already inside the loop - take advantage of it. </B>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">d)
Break long running callback methods into several shorter ones, and
pass control from one to the other via <FONT FACE="FreeMono, MS Mincho, monospace"><FONT SIZE=2 STYLE="font-size: 10pt"><B>setCallback</B></FONT></FONT><FONT FACE="FreeMono, MS Mincho, monospace"><FONT SIZE=2 STYLE="font-size: 10pt">()
</FONT></FONT>method:</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="FreeMono, MS Mincho, monospace"><FONT SIZE=2 STYLE="font-size: 10pt">Task
t1(TASK_IMMEDIATE, TASK_FAREVER, &callback);</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="FreeMono, MS Mincho, monospace"><FONT SIZE=2 STYLE="font-size: 10pt">void
callback() {</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="FreeMono, MS Mincho, monospace"><FONT SIZE=2 STYLE="font-size: 10pt">...
do some stuff</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="FreeMono, MS Mincho, monospace"><FONT SIZE=2 STYLE="font-size: 10pt">t1.setCallback(&callback_step2);</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="FreeMono, MS Mincho, monospace"><FONT SIZE=2 STYLE="font-size: 10pt">}</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="FreeMono, MS Mincho, monospace"><FONT SIZE=2 STYLE="font-size: 10pt">void
callback_step2() {</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="FreeMono, MS Mincho, monospace"><FONT SIZE=2 STYLE="font-size: 10pt">...
do more stuff</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="FreeMono, MS Mincho, monospace"><FONT SIZE=2 STYLE="font-size: 10pt">t1.setCallback(&callback_step3);</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="FreeMono, MS Mincho, monospace"><FONT SIZE=2 STYLE="font-size: 10pt">}</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="FreeMono, MS Mincho, monospace"><FONT SIZE=2 STYLE="font-size: 10pt">void
callback_step3() {</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="FreeMono, MS Mincho, monospace"><FONT SIZE=2 STYLE="font-size: 10pt">...
do last part of the stuff</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="FreeMono, MS Mincho, monospace"><FONT SIZE=2 STYLE="font-size: 10pt">t1.setCallback(&callback);</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="FreeMono, MS Mincho, monospace"><FONT SIZE=2 STYLE="font-size: 10pt">t1.delay(1000);</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="FreeMono, MS Mincho, monospace"><FONT SIZE=2 STYLE="font-size: 10pt">}</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">This
will execute all parts of the callback function in three successive
steps, scheduled immediately, but allowing other tasks in the chain
to run. Notice that task is scheduled to run immediately, and 1
second period is achieved by delaying the task for 1000 millis at the
last step.
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">Alternatively
you could schedule the task to run every 1000 millis and use
<FONT FACE="FreeMono, MS Mincho, monospace"><FONT SIZE=2 STYLE="font-size: 10pt">forceNextIteration()</FONT></FONT>
method in steps 1 and 2 (but not 3!)</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="FreeMono, MS Mincho, monospace"><FONT SIZE=2 STYLE="font-size: 10pt">Task
t1(1000, TASK_FOREVER, &callback);</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="FreeMono, MS Mincho, monospace"><FONT SIZE=2 STYLE="font-size: 10pt">void
callback() {</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="FreeMono, MS Mincho, monospace"><FONT SIZE=2 STYLE="font-size: 10pt">...
do some stuff</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="FreeMono, MS Mincho, monospace"><FONT SIZE=2 STYLE="font-size: 10pt">t1.setCallback(&callback_step2);</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="FreeMono, MS Mincho, monospace"><FONT SIZE=2 STYLE="font-size: 10pt">t1.forceNextIteration();</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="FreeMono, MS Mincho, monospace"><FONT SIZE=2 STYLE="font-size: 10pt">}</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="FreeMono, MS Mincho, monospace"><FONT SIZE=2 STYLE="font-size: 10pt">void
callback_step2() {</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="FreeMono, MS Mincho, monospace"><FONT SIZE=2 STYLE="font-size: 10pt">...
do more stuff</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="FreeMono, MS Mincho, monospace"><FONT SIZE=2 STYLE="font-size: 10pt">t1.setCallback(&callback_step3);</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="FreeMono, MS Mincho, monospace"><FONT SIZE=2 STYLE="font-size: 10pt">t1.forceNextIteration();</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="FreeMono, MS Mincho, monospace"><FONT SIZE=2 STYLE="font-size: 10pt">}</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="FreeMono, MS Mincho, monospace"><FONT SIZE=2 STYLE="font-size: 10pt">void
callback_step3() {</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="FreeMono, MS Mincho, monospace"><FONT SIZE=2 STYLE="font-size: 10pt">...
do last part of the stuff</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="FreeMono, MS Mincho, monospace"><FONT SIZE=2 STYLE="font-size: 10pt">t1.setCallback(&callback);</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="FreeMono, MS Mincho, monospace"><FONT SIZE=2 STYLE="font-size: 10pt">}</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">e)
Compile the library with <FONT FACE="FreeMono, MS Mincho, monospace"><FONT SIZE=2 STYLE="font-size: 10pt"><B>_TASK_TIMECRITICAL</B></FONT></FONT>
enabled and check if your tasks are falling behind schedule. If they
are - you need to optimize your code further (or maybe re-evaluate
your schedule). If they are not - all is well and you don't need to
do anything. E.g., I have a spider robot which needs to measure
distance, control motors, and keep track of the angle via querying
gyroscope and accelerometer every 10 ms. The idea was to flash
onboard LED if any of the tasks fall behind. At 10 ms interval for
the gyro the LED does not flash, which means none of the tasks are
blocking the others from starting on time.
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in; page-break-after: avoid">
<FONT SIZE=4><B>API DOCUMENTATION:</B></FONT></P>
<P CLASS="western" STYLE="margin-bottom: 0in; page-break-after: avoid">
<BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in; page-break-after: avoid">
<FONT SIZE=4><B>TASKS:</B></FONT></P>
<P CLASS="western" STYLE="margin-bottom: 0in; page-break-after: avoid">
<BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in">CREATION:</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><B>Task();</B></P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">Default
constructor.
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">Takes
no parameters and creates a task that could be scheduled to run at
every scheduling pass indefinitely, but does not have a callback
method defined, so no code execution will actually take place.
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">All
tasks are created <B>disabled</B> by default.</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in; page-break-after: avoid">
<B>Task(unsigned long aInterval, long aIterations, void
(*aCallback)(), Scheduler* aScheduler, bool aEnable, bool
(*aOnEnable)(), void (*aOnDisable)())</B></P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">Constructor
with parameters.
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">Creates
a task that is scheduled to run every <aInterval> milliseconds,
<aIterations> times, executing <aCallback> method on
every pass.
</P>
<OL>
<LI><P CLASS="western" STYLE="margin-bottom: 0in">aInterval is in
milliseconds (<B>default = 0)</B></P>
<LI><P CLASS="western" STYLE="margin-bottom: 0in">aIteration in
number of times, -1 for indefinite execution (<B>default = -1)</B><BR><B>Note:
</B>Tasks do not remember the number of iteration set initially.
After the iterations are done, internal iteration counter is 0. If
you need to perform another set of iterations, you need to set the
number of iterations again. <BR><B>Note: </B>Tasks which performed
all their iterations remain active.
</P>
<LI><P CLASS="western" STYLE="margin-bottom: 0in">aCallback is a
pointer to a void callback method without parameters (<B>default =
NULL)</B></P>
<LI><P CLASS="western" STYLE="margin-bottom: 0in">aScheduler –
<B>optional</B> reference to existing scheduler. If supplied (not
NULL) this task will be appended to the task chain of the current
scheduler). (<B>default = NULL)</B></P>
<LI><P CLASS="western" STYLE="margin-bottom: 0in">aEnable –
<B>optional</B>. Value of <B>true </B>will create task enabled.
(<B>default = false)</B></P>
<LI><P CLASS="western" STYLE="margin-bottom: 0in">aOnEnable is a
pointer to a bool callback method without parameters, invoked when
task is enabled. If OnEnable method returns <B>true</B>, task is
enabled. If <B>OnEnable</B> method return <B>false</B>, task remains
disabled (<B>default = NULL)</B></P>
<LI><P CLASS="western" STYLE="margin-bottom: 0in">aOnDisable is a
pointer to a void callback method without parameters, invoked when
task is disabled (<B>default = NULL)</B></P>
</OL>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">All
tasks are created <B>disabled</B> by default (unless <B>aEnable</B> =
true). You have to explicitly enable the task for execution.</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><B>NOTE:
</B>OnEnable callback method is called immediately when task is
enabled, which could be well ahead of the scheduled execution time of
the task. Please bear that in mind – other tasks, hardware, serial
interface may not even be initialized yet. It is always advisable to
explicitly enable tasks with OnEnable methods after all
initialization methods completed (e.g., at the end of <B>setup</B>()
method)
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">Enabled
task is scheduled for execution as soon as the Scheduler's <B>execute</B>()
methods gets control. In order to delay first run of the task, use
<B>enableDelayed</B> or <B>delay</B> method (for enabled tasks)
method.</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in; page-break-after: avoid">
<B>Task(void (*aCallback)(), Scheduler* aScheduler, bool
(*aOnEnable)(), void (*aOnDisable)())</B></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">If
compiled with support for Status Request objects, this constructor
creates a Task for activation on event (since such tasks must run
<B>waitFor() </B>method, their <I>interval</I>, <I>iteration</I> and
<I>enabled</I> status will be set by that method (<I>to 0, 1 and
false</I> respectively).</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><B>INFORMATION</B></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">The
following 3 “getter” methods return task status
(enabled/disabled), execution interval in milliseconds, number of
<I><B>remaining</B></I> iterations.
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><B>bool
isEnabled() </B>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><B>unsigned
long getInterval()</B></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><B>long
getIterations() </B>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><B>long getStartDelay()</B></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">If
library is compiled with <FONT FACE="Courier New, monospace">_TASK_TIMECRITICAL</FONT>
enabled, you can assess how much later the callback method was
invoked against when it was scheduled to be invoked. The return value
of <B>getStartDelay () </B>method provides this information in
milliseconds.
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><B>long getOverrun()</B></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">If
library is compiled with <FONT FACE="Courier New, monospace">_TASK_TIMECRITICAL</FONT>
enabled, tasks are monitored for “long running” scenario. A “long
running” task is a task that does not finish processing its
callback methods quickly, and thus creates a situation for itself and
other tasks where they don't run on a scheduled interval, but rather
“catch up” and are behind. When task scheduler sets the next
execution target time, it adds Task's execution interval to the
previously scheduled execution time:</P>
<P CLASS="western" ALIGN=CENTER STYLE="margin-left: 0.49in; margin-bottom: 0in">
<B>next execution time = current execution scheduled time + task
execution interval</B></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">If
<B>next execution time</B> happens to be already in the past (<B>next
execution time</B> < <B>millis()</B>), then task is considered
<I><B>overrun</B></I>. <B>GetOverrun</B> method returns number of
milliseconds between next execution time and current time. If the
<B>value is negative</B>, the task has overrun (cut into the) next
execution interval by that many milliseconds.
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">Positive
value indicate number of milliseconds of slack this task has for
execution purposes.
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><B>unsigned long
getRunCounter()</B></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">Returns
the number of the current run. “Current run” is the number of
times a callback method has been invoked since the last time a task
was enabled. <BR><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><B>NOTE:
</B>The <B>runCounter</B> value is incremented <I>before</I> callback
method is invoked. If a task is checking the <B>runCounter</B> value
within its callback method, then the first run value is 1.
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">If
task T1 is checking the <B>runCounter</B> value of another task (T2)
, then value = 0 indicates that T2 has not been invoked yet, and
value = 1 indicates that T2 has run once.
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><B>bool
isFirstIteration()</B></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">Indicates
whether current pass is (or will be) a first iteration of the task.
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><B>bool
isLastIteration()</B></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">For
tasks with a l<I>imited number of iterations only</I>, indicates
whether current pass is the last iteration.
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in; page-break-after: avoid">
<B>CONTROL:</B></P>
<P CLASS="western" STYLE="margin-bottom: 0in; page-break-after: avoid">
<BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><B>void enable();</B></P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">Enables
the task, and schedules it for immediate execution (without delay) at
this or next scheduling pass depending on when the task was enabled.
Scheduler will execute the next pass without any delay because there
is a task which was enabled and requires execution.
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><B>NOTE:
</B>if task being enabled is not assigned to a scheduler and is not
part of execution chain, then task <B>will not</B> be enabled.</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><B>NOTE:
</B>enable() invokes task’s <B>OnEnable</B> method (if not NULL)
<B>immediately</B>, which can prepare task for execution. <B>OnEnable</B>
must return a value of <B>true</B> for task to be enabled. If
<B>OnEnable</B> returns <B>false</B>, task remains disabled.
<B>OnEnable</B> is invoked every time <B>enable</B> is called,
regardless if task is already enabled or not. Alignment to current
millis() is performed after <B>OnEnable</B> exits, so any changes to
the interval inside <B>OnEnable</B> is taken into consideration.</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">TaskScheduler
allows tasks to be added to the a Scheduler and enabled at the time
of creation. <B>Be very careful</B> with such tasks – the <B>OnEnable
</B>method will be executed immediately, while certain objects (i.e.,
other Tasks, libraries) are not yet ready (e.g., <B>Wire.begin()</B>
was not yet called), or hardware not yet activated (pins not set to
INPUT or OUTPUT).
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">It
is very much recommended to to enable all tasks at the end of <B>setup()</B>
method after all initializations are done.
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">If
you require immediate execution of already enabled task, use
<B>forceNextIteratoin</B>() method instead of <B>enable</B>(): it
achieves the result, but does not call <B>OnEnable</B> method.
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><B>NOTE:</B>
in the event <B>enable</B>() method is called inside the <B>OnEnable</B>
callback method (thus basically creating indefinte loop),
TaskScheduler will only call <B>OnEnable</B> once (thus protecting
the Task against <B>OnEnable</B> infinite loop).
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in; page-break-after: avoid">
<B>bool enableIfNot();</B></P>
<P CLASS="western" STYLE="margin-bottom: 0in; page-break-after: avoid">
<BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">Enables
the task only if it was previously disabled. Returns previous enable
state: <B>true</B> if task was already enabled, and <B>false</B> if
task was disabled. Since <B>enable() </B>schedules Task for execution
immediately, this method provides a way to activate tasks and
schedule them for immediate execution only if they are not active
already.</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><B>void delay();</B></P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">Schedules
the task for execution after a delay (aInterval), but does not change
the enabled/disabled status of the task.
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><B>NOTE:
</B>a delay of 0 (zero) will delay task for current execution
interval. Use <B>forceNextIteration() </B>method to force execution
of the task’s callback during immediate next scheduling pass.
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><B>void
forceNextIteration();</B></P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">Schedules
the task for execution during immediate next scheduling pass.</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">The
Task must be already <I>enabled</I> prior to this method.
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><B>Note:
</B>Task’s schedule is adjusted to run from this moment in time.
For instance: if a task was running every 10 seconds: 10, 20, 30, ..,
calling <B>forceNextIteration </B>at 44th second of task execution
will make subsequent schedule look like: 44, 54, 64, 74, ..</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><B>void
enableDelayed();</B></P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">Enables
the task, and schedules it for execution after task's current
scheduling interval (aInterval).
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><B>void enableDelayed
(unsigned long aDelay);</B></P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">Enables
the task, and schedules it for execution after a specific delay
(aDelay, which maybe different from aInterval).
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><B>void restart();</B></P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">For
tasks with limited number of iterations only, <B>restart</B> method
will re-enable the task, set the number of iterations back to last
set value, and schedule task for execution as soon as possible.</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><B>void restartDelayed
(unsigned long aDelay);</B></P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">Same
as <B>restart()</B> method, with the only difference being that Task
is scheduled to run first iteration after a delay = <B>aDelay</B>
milliseconds.</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><B>bool disable();</B></P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">Disables
the task. Scheduler will not execute this task any longer, even if it
remains in the chain. Task <B>can</B> be later re-enabled for
execution.
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">Return
previous enabled state: <B>true</B> if task was enabled prior to
calling disable, and <B>false</B> otherwise.</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">If
not NULL, task’s <B>OnDisable</B> method is invoked <B>immediately</B>.
<B>OnDisable</B> is invoked only if task was in enabled state.
Calling <B>disable</B> 3 times for instance will invoke <B>OnDisable</B>
only once.</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><B>void set(unsigned
long aInterval, long aIterations, void (*aCallback)() , bool
(*aOnEnable)() , void (*aOnDisable)());</B></P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">Allows
dynamic control of task execution parameters in one method call.
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><B>Note</B><B>:
</B>OnEnable and OnDisable parameters can be omitted. In that case
they will be assigned to <B>NULL</B> and respective methods will no
longer be called. Therefore it is advisable to use either all five
parameters explicitly, or employ individual “setter” methods
below instead.
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in; page-break-after: avoid">
Next five “setter” methods allow changes of individual task
execution control parameters.
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><B>void
setInterval (unsigned long aInterval) </B>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><B>void
setIterations (long aIterations) </B>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><B>void
setCallback (void (*aCallback)()) </B>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><B>void
setOnEnable (bool (*aCallback)()) </B>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><B>void
setOnDisable (void (*aCallback)()) </B>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><B>NOTE: </B>Next
execution time calculation takes place <B>after</B> the callback
method is called, so new interval will be used immediately by the
scheduler. For the situations when one task is changing the interval
parameter for the other, <B>setInterval</B> method calls <B>delay
</B>explicitly to guarantee schedule change, however it <B>does not
</B>enable the task if task is disabled.</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><B>NOTE: </B>Tasks that
ran through all their allocated iterations are disabled.
<B>SetIterations()</B> method <B>DOES NOT</B> enable the task. Either
<B>enable</B> explicitly, or use <B>restart</B> methods.
</P>
<P CLASS="western" STYLE="margin-bottom: 0in">Please note that as a
result execution of the taks is <B>delayed</B> by the provided
interval. If immediate invocation is required, call
<B>forceNextIteration</B>() method after setting a new interval.
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><B>STATUS REQUEST
METHODS:</B></P>
<P CLASS="western" STYLE="margin-bottom: 0in; page-break-after: avoid">
<BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in; page-break-after: avoid">
<B>void waitFor(StatusRequest* aStatusRequest, unsigned long
aInterval = 0, long aIterations = 1)</B></P>
<P CLASS="western" STYLE="margin-bottom: 0in; page-break-after: avoid">
<B>void waitForDelayed(StatusRequest* aStatusRequest, unsigned long
aInterval = 0, long aIterations = 1)</B></P>
<P CLASS="western" STYLE="margin-bottom: 0in; page-break-after: avoid">
<BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">If
compiled with support for Status Requests, these methods make task
wait for the completion of <B>aStatusRequest</B> event.
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">By
default <B>waitFor() </B>sets tasks interval to <B>0 (zero)</B> for
immediate execution when event happens, and also sets the number of
<B>iterations to 1</B>. However, you can specify different interval
and number of iterations.
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">By
default <B>waitForDelayed() </B>sets tasks interval to a supplied
value or (if omitted or zero) keeps the current interval, so delayed
execution will take place when the event happens. It also sets the
number of <B>iterations to 1</B> by default if not supplied.
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">When
Status Request object completes, all tasks waiting on it are executed
during next scheduling pass. Tasks waiting via <B>waitFor</B>()
method are executed immediately. Tasks waiting via <B>waitForDelayed</B>()
method are activated, but executed after current or supplied interval
delay.
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><B>Note:
aStatusRequest</B> should be “activated” by calling <B>setWaiting()
</B>method before making a task wait on it. Otherwise, the task will
execute immediately.
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">The
sequence of events to use Status Request object is as follows:</P>
<OL>
<LI><P CLASS="western" STYLE="margin-bottom: 0in">Create a status
request object</P>
<LI><P CLASS="western" STYLE="margin-bottom: 0in">Activate status
request object (calling its <B>setWaiting</B>() method)</P>
<LI><P CLASS="western" STYLE="margin-bottom: 0in">Set up tasks to
wait of the event completion</P>
<LI><P CLASS="western" STYLE="margin-bottom: 0in">Signal completion
of event(s)</P>
</OL>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><B>StatusRequest*
getStatusRequest()</B></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">Returns
a StatusReqeust object this Task was waiting on.
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in; page-break-after: avoid">
<B>TASK ID, CONTROL POINTS METHODS:</B></P>
<P CLASS="western" STYLE="margin-bottom: 0in; page-break-after: avoid">
<BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in; page-break-after: avoid">
<B>void setId(unsigned int aID);</B></P>
<P CLASS="western" STYLE="margin-bottom: 0in; page-break-after: avoid">
<BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">If
compiled with support for Task IDs, this method will set the task ID
explicitly.
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">Calling
this method is not necessary as task IDs are assigned automatically
during task creation: 1, 2, 3, …</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in; page-break-after: avoid">
<B>unsigned int getId();</B></P>
<P CLASS="western" STYLE="margin-bottom: 0in; page-break-after: avoid">
<BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">If
compiled with support for Task IDs, this method return current task’s
ID.</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in; page-break-after: avoid">
<B>void setControlPoint (unsigned int aPoint);</B></P>
<P CLASS="western" STYLE="margin-bottom: 0in; page-break-after: avoid">
<BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">If
compiled with support for Task IDs, this method will set a control
point in the task’s code. Control points are similar to “try…catch”
blocks, with control point ID specifying where in the code the “try”
part started, and a mechanism like watchdog timer providing the
“catch” functionality.</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in; page-break-after: avoid">
<B>unsigned int getControlPoint()</B></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in; page-break-after: avoid">
<BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in; page-break-after: avoid">
If compiled with support for Task IDs, this method will return
currently set control point for this task.</P>
<P CLASS="western" STYLE="margin-bottom: 0in; page-break-after: avoid">
<BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in; page-break-after: avoid">
<BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><B>LOCAL TASK STORAGE
METHODS:</B></P>
<P CLASS="western" STYLE="margin-bottom: 0in; page-break-after: avoid">
<BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in; page-break-after: avoid">
<B>void setLtsPointer(void *aPtr);</B></P>
<P CLASS="western" STYLE="margin-bottom: 0in; page-break-after: avoid">
<BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">If
compiled with support for LTS, this method will set the task's local
storage pointer.</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in; page-break-after: avoid">
<B>void *getLtsPointer();</B></P>
<P CLASS="western" STYLE="margin-bottom: 0in; page-break-after: avoid">
<BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">If
compiled with support for LTS, this method will return reference to
the task's local storage.</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><B>Note:
</B>the value returned has type (void *), and needs to be re-cast
into appropriate pointer type. Please refer to example sketches for
implementation options.
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in; page-break-after: avoid">
<B>STATUS REQUEST:</B></P>
<P CLASS="western" STYLE="margin-bottom: 0in; page-break-after: avoid">
<BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in; page-break-after: avoid">
<B>CREATION:</B></P>
<P CLASS="western" STYLE="margin-bottom: 0in; page-break-after: avoid">
<BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><B>StatusRequest()</B><BR><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">Default
constructor.
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">Takes
no parameters. Creates Status Request object, which is assigned a
status of “completed” on creation.
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><B>void
setWaiting(unsigned int aCount = 1)</B></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">Activates
Status Request object. By default each object is set to wait on one
event only, however, if <B>aCount</B> is supplied, Status Request can
wait on multiple events. For instance, <B>setWaiting(3)</B> will wait
on three signals. An example could be waiting for completion of
measurements from 3 sensors.
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><B>bool signal(int
aStatus)</B></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">Signals
completion of the event to the Status Request object, and passes a
completion code, which could be interrogated later.
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><B>Note:
</B> passing a <B>negative</B> status code to the status request
object is considered reporting an error condition, and will complete
the status request regardless of how many outstanding signals it is
still waiting for.
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><B>Note</B>:
only the latest status code is kept.</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><B>bool signalComplete
(int aStatus)</B></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">Signals
completion of <B>ALL</B> events to the Status Request object, and
passes a completion code, which could be interrogated later. The
status request completes regardless of how many events it is still
waiting on.
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><B>bool pending() </B>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">Returns
<B>true</B> if status request is still waiting for event or events to
happen.</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><B>bool completed () </B>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">Returns
<B>true</B> if status has completed.</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><B>int getStatus()</B></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">Returns
the status code passed to the status request object by the <B>signal()
</B>and <B>signalComplete() </B>methods.
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">Any
<B>positive</B> number is considered a successful completion status.</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">A
0 (zero) is considered a default successful completion status.</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">Any
<B>negative</B> number is considered an error code and unsuccessful
completion of a request.</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in; page-break-after: avoid">
<BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in; page-break-inside: avoid; page-break-after: avoid">
<FONT SIZE=4><B>TASK SCHEDULER:</B></FONT></P>
<P CLASS="western" STYLE="margin-bottom: 0in; page-break-inside: avoid; page-break-after: avoid">
<BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in; page-break-inside: avoid; page-break-after: avoid">
<B>CREATION:</B></P>
<P CLASS="western" STYLE="margin-bottom: 0in; page-break-inside: avoid; page-break-after: avoid">
<BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><B>Scheduler()</B><BR><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">Default
constructor.
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">Takes
no parameters. Creates task scheduler with default parameters and an
empty task queue.
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><B>void init()</B></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">Initializes
the task queue and scheduler parameters, Executed as part of
constructor, so don't need to be explicitly called after creation.</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><B>Note:
</B>be default (if compiled with <FONT FACE="Courier New, monospace">_TASK_TIMECRITICAL</FONT>
enabled) scheduler is allowed to put processor to IDLE sleep mode. If
this behavior was changed via <B>allowSleep()</B> method, <B>inti()
</B>will <B>NOT</B> reset allow sleep particular parameter.
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR><B>void
addTask(Task& aTask)</B></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">Adds
task aTask to the execution queue (or chain) of tasks by appending it
to the end of the chain. If two tasks are scheduled for execution,
the sequence will match the order in which tasks were appended to the
chain. However, in reality, due to different timing of task
execution, the actual order may be different.
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><B>Note:
</B>Currently, changing the execution sequence in a chain dynamically
is not supported.
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">If
you need to reorder the chain sequence – initialize the scheduler
and re-add the tasks in a different order.
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR><B>void
deleteTask(Task& aTask)</B></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">Deletes
task aTask from the execution chain. The chain of remaining tasks is
linked together (i.e</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">if
original task chain is 1 → 2 → 3 → 4, deleting 3 will result in
1 → 2 → 4).</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><B>Note:
</B>it is not required to delete a task from the chain. A disabled
task will not be executed anyway, but you save a few microseconds per
scheduling pass by deleting it, since it is not even considered for
execution.
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">An
example of proper use of this method would be running some sort of
<B>initialize</B> task in the chain, and then deleting it from the
chain since it only needs to run once.
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><B>void allowSleep(bool
aState) </B>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">Available
in API only if compiled with <FONT FACE="Courier New, monospace">_TASK_TIMECRITICAL</FONT>
enabled. Controls whether scheduler is allowed (<B>aState =true</B>),
or not (<B>aState =false</B>) to put processor into IDLE sleep mode
in case not tasks are scheduled to run.</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">The
<B>default</B> behavior of scheduler upon creation is to allow sleep
mode.
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR><B>void
enableAll(bool aRecursive= true)</B></P>
<P CLASS="western" STYLE="margin-bottom: 0in"><B>void disableAll(bool
aRecursive= true)</B></P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">enables
and disables (respectively) all tasks in the chain. Convenient if
your need to enable/disable majority of the tasks (i.e. disable all
and then enable one).
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">If
support for layered task priority is enabled, supplying <B>aRecursive</B>
parameter will enable/disable higher priority tasks as well (<B>true</B>,
default), or tasks only on this priority layer (<B>false</B>).
</P>
<P CLASS="western" STYLE="margin-bottom: 0in; page-break-after: avoid">
<BR><B>Task& currentTask()<BR></B><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">Returns
reference to the task, currently executing via <B>execute()</B> loop
<B>OR </B>for OnEnable and OnDisable methods, reference to the task
being enabled or disabled.
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">This
distinction is important because one task can activate the other, and
OnEnable should be referring to the task being enabled, not being
executed.
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">Could
be used by callback methods to identify which Task actually invoked
this callback method.</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in; page-break-after: avoid">
<B>void* currentLts()<BR></B><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">Returns
pointer to Local Task Storage of the task, currently executing via
<B>execute()</B> loop <B>OR </B>for OnEnable and OnDisable methods,
task being enabled or disabled.
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR><B>bool execute()</B></P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">Executes
one scheduling pass, including (in case of the base priority
scheduler) end-of-pass sleep. This method is typically placed inside
the <B>loop()</B> method of the sketch. Since <B>execute</B> exits
after every pass, you can put additional statements after <B>execute</B>
inside the <B>loop().</B></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><B>If
layered task prioritization is enabled, all higher priority tasks
will be evaluated and invoked by the base <FONT FACE="Courier New, monospace">execute()</FONT>
method. There is no need to call <FONT FACE="Courier New, monospace">execute()</FONT>
of the higher priority schedulers explicitly. </B>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">Generally,
base priority execute will perform the following steps:</P>
<OL>
<LI><P CLASS="western" STYLE="margin-bottom: 0in">Call higher
priority scheduler’s execute method, if provided.</P>
<LI><P CLASS="western" STYLE="margin-bottom: 0in">Ignore task
completely if it is disabled.</P>
<LI><P CLASS="western" STYLE="margin-bottom: 0in">Disable task if it
ran out of iterations (calling OnDisable, if necessary).</P>
<LI><P CLASS="western" STYLE="margin-bottom: 0in">Check if task is
waiting on a StatusRequest object, and make appropriate scheduling
arrangements</P>
<LI><P CLASS="western" STYLE="margin-bottom: 0in">Perform necessary
timing calculations</P>
<LI><P CLASS="western" STYLE="margin-bottom: 0in">Invoke task's
callback method, if it is time to do so, and one is provided.
</P>
<LI><P CLASS="western" STYLE="margin-bottom: 0in">Put
microcontroller to sleep (if requested and supported) if none of the
tasks were invoked.
</P>
</OL>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><B>Please
NOTE:</B> schedule-related calculations are performed prior to task's
callback method invocation. This allows tasks to manipulate their
runtime parameters (like execution interval) directly.</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><B>bool isOverrun()</B></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">If
library is compiled with <FONT FACE="Courier New, monospace">_TASK_TIMECRITICAL</FONT>
enabled, this method returns <B>true</B> if currently invoked task
has overrun its scheduled start time when it was invoked. Returns
<B>false</B> if task has been invoked according to schedule.</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in; page-break-after: avoid">
<BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in; page-break-after: avoid">
<B>TASK PRIORITY:</B></P>
<P CLASS="western" STYLE="margin-bottom: 0in; page-break-after: avoid">
<BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><B>void
setHighPriorityScheduler(Scheduler* aScheduler);</B><BR><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">If
library is compiled with <FONT FACE="Courier New, monospace">_TASK_PRIORITY
</FONT>enabled, this method associates current scheduler with a
higher priority scheduler.
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><B>NOTE:
</B>Only one <B>execute() </B>method needs to be explicitly called in
the main <B>loop(). </B>That is the execute method of <B>base</B>
priority scheduler. All higher priority schedulers are called by the
base priority scheduler.</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><B>static Scheduler&
currentScheduler()</B></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">If
library is compiled with <FONT FACE="Courier New, monospace">_TASK_PRIORITY
</FONT>enabled, this method returns reference to a scheduler, which
invoked current task.
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><B>NOTE:
Please refer to examples 11 and 12 for illustration of Task Priority
functionality</B></P>
<P CLASS="western" STYLE="margin-bottom: 0in; page-break-after: avoid">
<BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in; page-break-after: avoid">
<BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in; page-break-after: avoid">
<BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in; page-break-after: avoid">
<B>CONSTANTS:</B></P>
<P CLASS="western" STYLE="margin-bottom: 0in; page-break-after: avoid">
<BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in; page-break-after: avoid">
<B>TASK_SECOND (1000)</B></P>
<P CLASS="western" STYLE="margin-left: 0.98in; margin-bottom: 0in">Task
interval of 1 second</P>
<P CLASS="western" STYLE="margin-left: 0.98in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in; page-break-after: avoid">
<B>TASK_MINUTE (60000)</B></P>
<P CLASS="western" STYLE="margin-left: 0.98in; margin-bottom: 0in">Task
interval of 1 minute</P>
<P CLASS="western" STYLE="margin-left: 0.98in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in; page-break-after: avoid">
<B>TASK_HOUR (3600000)</B></P>
<P CLASS="western" STYLE="margin-left: 0.98in; margin-bottom: 0in">Task
interval of 1 hour</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in; page-break-after: avoid">
<B>TASK_FOREVER (-1)</B></P>
<P CLASS="western" STYLE="margin-left: 0.98in; margin-bottom: 0in">Task
number of iterations for infinite number of iterations</P>
<P CLASS="western" STYLE="margin-left: 0.98in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in; page-break-after: avoid">
<B>TASK_ONCE (1)</B></P>
<P CLASS="western" STYLE="margin-left: 0.98in; margin-bottom: 0in">Task
single iteration</P>
<P CLASS="western" STYLE="margin-left: 0.98in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in; page-break-after: avoid">
<B>TASK_IMMEDIATE (0)</B></P>
<P CLASS="western" STYLE="margin-left: 0.98in; margin-bottom: 0in">Task
interval for immediate execution</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in; page-break-before: always; page-break-after: avoid">
<B>IMPLEMENTATION SCENARIOS AND IDEAS:</B></P>
<P CLASS="western" STYLE="margin-bottom: 0in; page-break-after: avoid">
<BR>
</P>
<OL>
<LI><P CLASS="western" STYLE="margin-bottom: 0in; page-break-after: avoid">
<B>EVENT DRIVEN PROGRAMMING</B></P>
</OL>
<P CLASS="western" STYLE="margin-bottom: 0in; page-break-after: avoid">
<BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in">Each of the processes
of your application becomes a separate and distinct programming area,
which may or may not interact and control each other.
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in">Example:
</P>
<P CLASS="western" STYLE="margin-bottom: 0in">In a plant watering
system you need to measure soil humidity, control pump and display
the results</P>
<P CLASS="western" STYLE="margin-bottom: 0in">Each of the areas
becomes a task:</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>Task
<B>tMeasure</B> (TMEASURE_INTERVAL*SECOND, TASK_FOREVER,
&measureCallback);<BR>Task <B>tWater</B>
(TWATER_INTERVAL*SECOND, RETRIES, &waterCallback);<BR>Task
<B>tDisplay</B> (TDISPLAY_INTERVAL*SECOND, TASK_FOREVER,
&displayCallback); <BR></FONT></FONT><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>Scheduler
</FONT></FONT><FONT FACE="Courier New, monospace"><FONT SIZE=2><B>taskManager</B></FONT></FONT><FONT FACE="Courier New, monospace"><FONT SIZE=2>;</FONT></FONT><BR><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in">Further, once you turn
on the pump, you keep it running for TWATER_INTERVAL interval and
then turn it off. Turning off a pump is also a task which only needs
to run once for every time the pump is turned on:</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>Task
</FONT></FONT><FONT FACE="Courier New, monospace"><FONT SIZE=2><B>tWaterOff</B></FONT></FONT><FONT FACE="Courier New, monospace"><FONT SIZE=2>
(WATERTIME*SECOND, TASK_ONCE,</FONT></FONT><FONT FACE="Courier New, monospace">
&waterOffCallback);</FONT><BR><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in">Example of the callback
method:</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>void
waterOffCallback() {<BR> motorOff();<BR>
tWater.enableDelayed();<BR>}</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>or</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>void
waterCallback() {<BR> if (tWater.getIterations()) {</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>//
If this is not the last iteration = turn the pump on<BR>
motorOn();<BR> tWaterOff.set(parameters.watertime * TASK_SECOND,
TASK_ONCE, &waterOffCallback);<BR>
tWaterOff.enableDelayed();<BR> return;<BR> }</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>//
We could not reach target humidity – something is wrong<BR>
motorOff;<BR> taskManager.disableAll();<BR> tError.enable();<BR>}</FONT></FONT></P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><FONT FACE="Times New Roman, serif">Your
sample <B>setup</B>() and <B>loop</B>() (partially) are as follows. </FONT>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><FONT FACE="Times New Roman, serif"><B>Note:
</B>please note that tWater is <B>not</B> activated during setup().
It is activated by tMeasure callback once the watering conditions are
met. </FONT>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><FONT SIZE=2><FONT FACE="Times New Roman, serif"> void
</FONT><FONT FACE="Courier New, monospace">setup()</FONT></FONT></P>
<P CLASS="western" STYLE="margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>
...</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT SIZE=2><FONT FACE="Courier New, monospace">tWater.setIterations(parameters.retries);<BR>
tWaterOff.setInterval(parameters.watertime * SECOND);<BR><BR><BR>
taskManager.init();<BR> taskManager.addTask(tMeasure);<BR>
taskManager.addTask(tDisplay);<BR> taskManager.addTask(tWater);<BR>
taskManager.addTask(tWaterOff);<BR> <BR> tMeasure.enable();<BR>
tDisplay.enable();<BR><BR> currentHumidity =
measureHumidity();<BR>}<BR><BR><BR>void loop ()<BR>{<BR>
taskManager.execute();<BR>}</FONT><FONT FACE="Times New Roman, serif"><BR></FONT></FONT><BR>
</P>
<OL START=2>
<LI><P CLASS="western" STYLE="margin-bottom: 0in; page-break-after: avoid">
“<FONT FACE="Times New Roman, serif"><B>NATIVE” SUPPORT FOR
FINITE STATE MACHINE</B></FONT></P>
</OL>
<P CLASS="western" STYLE="margin-bottom: 0in; page-break-after: avoid">
<BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><FONT FACE="Times New Roman, serif">Define
“states” as callback method or methods. Each callback method
executes activities specific to a “state” and then “transitions”
to the next state by assigning next callback method to the task. </FONT>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><FONT FACE="Times New Roman, serif">Transition
from one state to the next is achieved by setting next callback
method at the end of preceding one. </FONT>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><FONT FACE="Times New Roman, serif"><B>Note:
</B>do not call the next callback method explicitly. Yield to the
scheduler, and let the scheduler take care of next iteration during
the next pass. (Thus giving other tasks change to run their callback
methods). </FONT>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><FONT FACE="Times New Roman, serif">Example:
Blinking LED 2 times a second could be achieved this way</FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>Scheduler
ts;</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>Task
tLedBlinker (500, TASK_FOREVER, &ledOnCallback, &ts, true);</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>void
ledOnCallback() {</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2> turnLedOn();</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2> tLedBlinker.setCallback(&ledOffCallback);</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>}</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>void
ledOffCallback() {</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2> turnLedOff();</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2> tLedBlinker.setCallback(&ledOnCallback);</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>}</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>setup()
{</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>}</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>loop
() {</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2> ts.execute();</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>}</FONT></FONT><FONT FACE="Times New Roman, serif"><BR></FONT><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><FONT FACE="Times New Roman, serif">Obviously
the example is simple, but gives the idea of how the tasks could be
used to go through states.</FONT></P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<OL START=3>
<LI><P CLASS="western" STYLE="margin-bottom: 0in; page-break-after: avoid">
<FONT FACE="Times New Roman, serif"><B>MULTIPLE POSSIBLE CALLBACKS
FOR TASK</B></FONT></P>
</OL>
<P CLASS="western" STYLE="margin-bottom: 0in; page-break-after: avoid">
<BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><FONT FACE="Times New Roman, serif">There
may be a need to select an option for callback method based on
certain criteria, or randomly. </FONT>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><FONT FACE="Times New Roman, serif">You
can achieve that by defining an array of callback method pointers and
selecting one based on the criteria you need. </FONT>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><FONT FACE="Times New Roman, serif">Example:
when a robot detects an obstacle, it may go left, right backwards,
etc. Each of the “directions” or “behaviors” are represented
by a different callback methods. </FONT>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><FONT FACE="Times New Roman, serif">Another
example of using multiple callbacks:</FONT></P>
<P CLASS="western" STYLE="margin-bottom: 0in"><FONT FACE="Times New Roman, serif">You
may need to “initialize” variables for a particular task.</FONT></P>
<P CLASS="western" STYLE="margin-bottom: 0in"><FONT FACE="Times New Roman, serif">In
this case, define a tasks with two callbacks:</FONT></P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>Task
<B>tWork</B> (T_INTERVAL, TASK_FOREVER, &workCallbackInit);</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">…</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>void
workCallbackInit() {</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2> //
do your initializationstuff here</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2> </FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2> //
finally assigne the main callback method </FONT></FONT>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2> tWork.setCallback(&workCallback);</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>}</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>void
workCallback() {</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2> //
main callback method</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2> …</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>}</FONT></FONT></P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><FONT FACE="Times New Roman, serif">The
task will initialize during first execution pass and switch to
“regular” callback execution starting with second pass. There is
a delay between first and second passes of the task (scheduling
period, if defined). In order to execute the second pass immediately
after initialization first pass, change the above code like this:</FONT></P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>void
workCallbackInit() {</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2> //
do your initializationstuff here</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2> </FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2> //
finally assigne the main callback method </FONT></FONT>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2> tWork.setCallback(&workCallback);</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2> tWork.enable();</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>}</FONT></FONT></P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><FONT FACE="Times New Roman, serif">The
task will run initialization first, then immediately second pass, and
then switch to processing at regular intervals starting with a third
pass. </FONT>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<OL START=3>
<LI><P CLASS="western" STYLE="margin-bottom: 0in; page-break-after: avoid">
<FONT FACE="Times New Roman, serif"><B>INTERRUP-DRIVEN EXECUTION
SUPPORT </B></FONT>
</P>
</OL>
<P CLASS="western" STYLE="margin-bottom: 0in; page-break-after: avoid">
<BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><FONT FACE="Times New Roman, serif">In
case of interrupt-driven program flow, tasks could be scheduled to
run once to request asynchronous execution (request), and then
re-enabled (restarted) again with a different callback method to
process the results. </FONT>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-bottom: 0in"><FONT FACE="Times New Roman, serif"><B>Example</B>:
event driven distance calculation for ultrasonic pulses. EchoPin #6
triggers pin change interrupts on rising and falling edges to
determine the length of ultrasonic pulse.</FONT></P>
<P CLASS="western" STYLE="margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>#include
<DirectIO.h><BR>#include <TaskScheduler.h><BR>#include
<PinChangeInt.h><BR><BR><BR>#define TRIGGERPIN 5<BR>#define
ECHOPIN 6<BR><BR>Output<TRIGGERPIN>
pTrigger;<BR>Input<ECHOPIN> pEcho;<BR><BR>Scheduler
r;<BR><BR>Task tMeasure(TASK_SECOND, TASK_FOREVER, &measureCallback,
&r, true);<BR>Task tDisplay(TASK_SECOND, TASK_FOREVER,
&displayCallback, &r, true);<BR>Task tPing(TASK_IMMEDIATE,
TASK_ONCE, &pingCalcCallback, &r, false);<BR><BR><BR>volatile
bool pulseBusy = false;<BR>volatile bool pulseTimeout =
false;<BR>volatile unsigned long pulseStart = 0;<BR>volatile unsigned
long pulseStop = 0;<BR>volatile unsigned long pingDistance =
0;<BR><BR><BR>void pingTrigger(unsigned long aTimeout) {<BR> if
(pulseBusy) return; // do not trigger if in the middle of a pulse<BR>
if (pEcho == HIGH) return; // do not trigger if ECHO pin is high<BR>
<BR> pulseBusy = true;<BR> pulseTimeout = false;</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2><BR>
pTrigger = LOW;<BR> delayMicroseconds(4);<BR> pTrigger = HIGH;<BR><BR>
tPing.setInterval (aTimeout);<BR><BR> delayMicroseconds(10);<BR>
pTrigger = LOW; <BR></FONT></FONT><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>tPing.restartDelayed();
// timeout countdown starts now<BR></FONT></FONT><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>//
will start the pulse clock on the rising edge of ECHO pin</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>PCintPort::attachInterrupt(ECHOPIN,
&pingStartClock, RISING); <BR>}<BR><BR></FONT></FONT><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>//
Start clock on the <B>rising</B> edge of the ultrasonic pulse<BR>void
pingStartClock() {<BR> pulseStart = micros();<BR>
PCintPort::detachInterrupt(ECHOPIN); // not sure this is necessary<BR>
PCintPort::attachInterrupt(ECHOPIN, &pingStopClock, FALLING); <BR>
tPing.restartDelayed();<BR>}<BR><BR>// Stop clock on the <B>falling</B>
edge of the ultrasonic pulse<BR>void pingStopClock() {<BR> pulseStop
= micros();<BR> PcintPort::detachInterrupt(ECHOPIN);</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>pingDistance =
pulseStop - pulseStart;<BR> pulseBusy = false;<BR> tPing.disable();
// disable timeout<BR>}<BR></FONT></FONT><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>//
Stop clock because of the timeout – the wave did not return<BR>void
pingCalcCallback() {<BR> if (pulseBusy) {<BR> pingStopClock();<BR>
}<BR> pulseTimeout = true;<BR>}<BR><BR><BR><BR>// Initial measure
callback sets the trigger<BR>void measureCallback() {<BR> if
(pulseBusy) { // already measuring, try again<BR>
tMeasure.enable();<BR> return;<BR> }<BR> pingTrigger(30); // 30
milliseconds or max range of ~5.1 meters<BR>
tMeasure.setCallback(&measureCallbackWait);<BR>}<BR></FONT></FONT><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>//
Wait for the measurement to <BR>void measureCallbackWait() {<BR> if
(pulseBusy) return;<BR> tMeasure.setCallback(&measureCallback);
<BR>}<BR><BR><BR>bool state = true;<BR><BR>void displayCallback() {<BR>
char d[256];<BR> <BR> unsigned long cm = pingDistance * 17 / 100;
// cm<BR> <BR> snprintf(d, 256, "pulseStart =
%8lu\tpulseStop=%8lu\tdistance, cm=%8lu", pulseStart, pulseStop,
cm);<BR> Serial.println(d);<BR> <BR>}<BR><BR>void setup() {<BR> //
put your setup code here, to run once:<BR> <BR>
Serial.begin(115200);<BR> <BR><BR> pTrigger = LOW;<BR> pEcho =
LOW;<BR> <BR>}<BR><BR>void loop() {<BR> // put your main code here,
to run repeatedly:<BR> r.execute();<BR>}<BR></FONT></FONT><BR>
</P>
<OL START=3>
<LI><P CLASS="western" STYLE="margin-bottom: 0in; page-break-after: avoid">
<FONT FACE="Times New Roman, serif"><B>USING ONENABLE AND ONDISBALE
METHODS </B></FONT>
</P>
</OL>
<P CLASS="western" STYLE="margin-bottom: 0in; page-break-after: avoid">
<BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Times New Roman, serif">Consider
a task to flash onboard LED for 5 seconds with random frequency. Task
should be repeated every 30 seconds indefinitely. Since frequency is
random, there are two challenges:</FONT></P>
<OL START=3>
<OL>
<LI><P CLASS="western" STYLE="margin-bottom: 0in"><FONT FACE="Times New Roman, serif">We
need to make sure LED is turned OFF at the last iteration</FONT></P>
<LI><P CLASS="western" STYLE="margin-bottom: 0in"><FONT FACE="Times New Roman, serif">We
need to calculate random frequency every time</FONT></P>
</OL>
</OL>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Times New Roman, serif">Below
is the implementation using TaskScheduler </FONT>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2><BR></FONT></FONT><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>#define
_TASK_SLEEP_ON_IDLE_RUN</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>#include
<TaskScheduler.h></FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>#define
LEDPIN 13</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>Scheduler
ts;</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>Task
tWrapper(30000, TASK_FOREVER, &WrapperCallback, &ts, true);</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>Task
tBlink(5000, TASK_ONCE, NULL, &ts, false, &BlinkOnEnable,
&BlinkOnDisable);</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>Task
tLED(TASK_IMMEDIATE, TASK_FOREVER, NULL, &ts, false, NULL,
&LEDOff);</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>void
WrapperCallback() {</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>Serial.println("In
WrapperCallback");</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>tBlink.restartDelayed();
// LED blinking is initiated </FONT></FONT>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>//every
30 seconds for 5 seconds</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>}</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>//
Upon being enabled, tBlink will define the parameters</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>//
and enable LED blinking task, which actually controls</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>//
the hardware (LED in this example)</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>bool
BlinkOnEnable() {</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>Serial.println("In
BlinkOnEnable");</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>tLED.setInterval(
500 + random(501) );</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>tLED.setCallback(
&LEDOn);</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>tLED.enable();</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>return true; //
Task should be enabled</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>}</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>//
tBlink does not really need a callback method</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>//
since it just waits for 5 seconds for the first </FONT></FONT>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>//
and only iteration to occur. Once the iteration</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>//
takes place, tBlink is disabled by the Scheduler, </FONT></FONT>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>//
thus executing its OnDisable method below.</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>void
BlinkOnDisable() {</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>Serial.println("In
BlinkOnDisable");</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>tLED.disable();</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>}</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>void
LEDOn () {</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>Serial.println("In
LEDOn");</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>digitalWrite(LEDPIN,
HIGH);</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>tLED.setCallback(
&LEDOff);</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>}</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>void
LEDOff () {</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>Serial.println("In
LEDOff");</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>digitalWrite(LEDPIN,
LOW);</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>tLED.setCallback(
&LEDOn);</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>}</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>//
Note that LEDOff method serves as OnDisable method</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>//
to make sure the LED is turned off when the tBlink</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>//
task finishes (or disabled ahead of time)</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>void
setup() {</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>Serial.begin(115200);
</FONT></FONT>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>pinMode(LEDPIN,
OUTPUT); </FONT></FONT>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>}</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>void
loop() {</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>// put your main
code here, to run repeatedly:</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>ts.execute();</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>}</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<OL START=3>
<LI><P CLASS="western" STYLE="margin-bottom: 0in; page-break-after: avoid">
<FONT FACE="Times New Roman, serif"><B>USING STATUS REQUEST OBJECTS
</B></FONT>
</P>
</OL>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in; page-break-after: avoid">
<BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Times New Roman, serif"><FONT SIZE=2 STYLE="font-size: 11pt">This
test emulates querying 3 sensors once every 10 seconds, each could
respond with a different delay (ultrasonic sensors for instance) and
printing a min value of the three when all three have reported their
values.</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Times New Roman, serif"><FONT SIZE=2 STYLE="font-size: 11pt">The
overall timeout of 1 second is setup as well.</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Times New Roman, serif"><FONT SIZE=2 STYLE="font-size: 11pt">An
error message needs to be printed if a timeout occurred instead of a
value.</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>#define
_TASK_SLEEP_ON_IDLE_RUN</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>#define
_TASK_STATUS_REQUEST</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>#include
<TaskScheduler.h></FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>StatusRequest
measure;</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>Scheduler
ts; </FONT></FONT>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>Task
tCycle(10000, TASK_FOREVER, &CycleCallback, &ts, true);</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>Task
tMeasure(TASK_SECOND, TASK_ONCE, &MeasureCallback, &ts,
false, &MeasureEnable, &MeasureDisable);</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>Task
tCalculate(&CalcCallback, &ts);</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>Task
tSensor1(TASK_IMMEDIATE, TASK_ONCE, &S1Callback, &ts, false,
&S1Enable);</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>Task
tSensor2(TASK_IMMEDIATE, TASK_ONCE, &S2Callback, &ts, false,
&S2Enable);</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>Task
tSensor3(TASK_IMMEDIATE, TASK_ONCE, &S3Callback, &ts, false,
&S3Enable);</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>long
distance, d1, d2, d3;</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>void
CycleCallback() {</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>Serial.println("CycleCallback:
Initiating measurement cycle every 10 seconds");</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>tMeasure.restartDelayed();</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>}</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>bool
MeasureEnable() {</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>Serial.println("MeasureEnable:
Activating sensors"); </FONT></FONT>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>distance = 0;</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>measure.setWaiting(3);
// Set the StatusRequest to wait for 3 signals. </FONT></FONT>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>tCalculate.waitFor(&measure);</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>tSensor1.restart();</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>tSensor2.restart();</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>tSensor3.restart();</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>return true;</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>}</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>void
MeasureCallback() {</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>Serial.println("MeasureCallback:
Invoked by calculate task or one second later"); </FONT></FONT>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>if
(measure.pending()) {</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>tCalculate.disable();</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>measure.signalComplete(-1);
// signal error</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>Serial.println("MeasureCallback:
Timeout!");</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>}</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>else {</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>Serial.print("MeasureCallback:
Min distance=");Serial.println(distance);</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>}</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>}</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>void
MeasureDisable() {</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>Serial.println("MeasureDisable:
Cleaning up"); </FONT></FONT>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>tSensor1.disable();</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>tSensor2.disable();</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>tSensor3.disable();</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>}</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>void
CalcCallback() {</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>Serial.println("CalcCallback:
calculating"); </FONT></FONT>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>distance = -1;</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>if (
measure.getStatus() >= 0) { // only calculate if statusrequest
ended successfully</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>distance = d1 <
d2 ? d1 : d2;</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>distance = d3 <
distance ? d3 : distance;</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>tMeasure.forceNextIteration();</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>}</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>}</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>/**
Simulation code for sensor 1</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"> <FONT FACE="Courier New, monospace"><FONT SIZE=2>*
----------------------------</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>*/</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>bool
S1Enable() {</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>Serial.print("S1Enable:
Triggering sensor1. Delay="); </FONT></FONT>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>tSensor1.setInterval(
random(1200) ); // Simulating sensor delay, which could go over 1
second and cause timeout</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>d1 = 0;</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>Serial.println(
tSensor1.getInterval() );</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>return true;</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>}</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>void
S1Callback() {</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>Serial.print("S1Callback:
Emulating measurement. d1="); </FONT></FONT>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>d1 = random(501); //
pick a value from 0 to 500 "centimeters" simulating a
measurement </FONT></FONT>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>measure.signal();</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>Serial.println(d1); </FONT></FONT>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>}</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>/**
Simulation code for sensor 2</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"> <FONT FACE="Courier New, monospace"><FONT SIZE=2>*
----------------------------</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>*/</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>bool
S2Enable() {</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>Serial.print("S2Enable:
Triggering sensor2. Delay="); </FONT></FONT>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>tSensor2.setInterval(
random(1200) ); // Simulating sensor delay, which could go over 1
second and cause timeout</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>d2 = 0;</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>Serial.println(
tSensor2.getInterval() );</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>return true;</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>}</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>void
S2Callback() {</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>Serial.print("S2Callback:
Emulating measurement. d2="); </FONT></FONT>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>d2 = random(501); //
pick a value from 0 to 500 "centimeters" simulating a
measurement</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>measure.signal();</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>Serial.println(d2);
</FONT></FONT>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>}</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>/**
Simulation code for sensor 3</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"> <FONT FACE="Courier New, monospace"><FONT SIZE=2>*
----------------------------</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>*/</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>bool
S3Enable() {</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>Serial.print("S3Enable:
Triggering sensor3. Delay="); </FONT></FONT>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>tSensor3.setInterval(
random(1200) ); // Simulating sensor delay, which could go over 1
second and cause timeout</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>d3 = 0;</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>Serial.println(
tSensor3.getInterval() );</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>return true;</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>}</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>void
S3Callback() {</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>Serial.print("S3Callback:
Emulating measurement. d3="); </FONT></FONT>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>d3 = random(501); //
pick a value from 0 to 500 "centimeters" simulating a
measurement</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>measure.signal();</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>Serial.println(d3); </FONT></FONT>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>}</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>/**
Main Arduino code</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"> <FONT FACE="Courier New, monospace"><FONT SIZE=2>*
Not much is left here - everything is taken care of by the framework</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>*/</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>void
setup() {</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>Serial.begin(115200);</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>Serial.println("TaskScheduler
StatusRequest Sensor Emulation Test. Complex Test."); </FONT></FONT>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>randomSeed(analogRead(A1)+millis());</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>}</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>void
loop() {</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>ts.execute();</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>}</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<OL START=3>
<LI><P CLASS="western" STYLE="margin-bottom: 0in; page-break-after: avoid">
<FONT FACE="Times New Roman, serif"><B>USING LOCAL TASK STORAGE
POINTER </B></FONT>
</P>
</OL>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in; page-break-after: avoid">
<BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Times New Roman, serif"><FONT SIZE=2 STYLE="font-size: 11pt">Tasks
can store a pointer to specific variable, structure or array, which
represents variables specific for a particular task. This may be
needed if you plan to use same callback method for multiple tasks.</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Times New Roman, serif"><FONT SIZE=2 STYLE="font-size: 11pt">Consider
a scenario where you have several sensors of the same type. The
actual process of triggering measurement and collecting information
is identical. The only difference is the sensor address and a
variable for storing the results. </FONT></FONT>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Times New Roman, serif"><FONT SIZE=2 STYLE="font-size: 11pt">In
this case each of the tasks, which performs measurement will utilize
the same callback methods. The only difference will be the variables
(specific for each of the sensor). </FONT></FONT>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Times New Roman, serif"><FONT SIZE=2 STYLE="font-size: 11pt">Let's
define a sensor data structure and declare a couple of variables (for
2 sensors for instance)</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P LANG="" CLASS="western" STYLE="margin-left: 0.98in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>typedef struct {</FONT></FONT></P>
<P LANG="" CLASS="western" STYLE="margin-left: 0.98in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2> unsigned int
address;</FONT></FONT></P>
<P LANG="" CLASS="western" STYLE="margin-left: 0.98in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2> unsigned
long distance;</FONT></FONT></P>
<P LANG="" CLASS="western" STYLE="margin-left: 0.98in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>} sensor_data;</FONT></FONT></P>
<P LANG="" CLASS="western" STYLE="margin-left: 0.98in; margin-bottom: 0in">
<BR>
</P>
<P LANG="" CLASS="western" STYLE="margin-left: 0.98in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>sensor_data s1, s2; </FONT></FONT>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Times New Roman, serif"><FONT SIZE=2 STYLE="font-size: 11pt">Two
separate tasks are running to collect sensor data.</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Times New Roman, serif"><FONT SIZE=2 STYLE="font-size: 11pt">(Note
that both tasks refer to the same callback methods)</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P LANG="" CLASS="western" STYLE="margin-left: 0.98in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>Scheduler ts;</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.98in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2><SPAN LANG="">Task
t1(100, </SPAN>TASK_FOREVER<SPAN LANG="">, &Measure, &ts,
false, &MeasureOn); </SPAN></FONT></FONT>
</P>
<P CLASS="western" STYLE="margin-left: 0.98in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2><SPAN LANG="">Task
t2(100, </SPAN>TASK_FOREVER<SPAN LANG="">, &Measure, &ts,
false, &MeasureOn); </SPAN></FONT></FONT>
</P>
<P CLASS="western" STYLE="margin-left: 0.98in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Times New Roman, serif"><FONT SIZE=2 STYLE="font-size: 11pt">Assign
pointers to the respective variables in the <B>setup</B>() method:</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.98in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>void
setup() {</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.98in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 1.48in; margin-bottom: 0in">…</P>
<P CLASS="western" STYLE="margin-left: 1.48in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>t1.setLtsPointer(&s1);</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 1.48in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>t2.setLtsPointer(&s2);</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 1.48in; margin-bottom: 0in">…</P>
<P CLASS="western" STYLE="margin-left: 0.98in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.98in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>}</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.98in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Times New Roman, serif"><FONT SIZE=2 STYLE="font-size: 11pt">Obtain
reference to specific <B>sensor_data</B> structure inside the common
callback method:</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.98in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>void
Measure() {</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.98in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2> Task&
T = ts.currentTask(); </FONT></FONT>
</P>
<P CLASS="western" STYLE="margin-left: 0.98in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2> Sensor_data&
V = *((sensor_data*) T.getLtsPointer());</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.98in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>//
For t1, V will be pointing at s1</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.98in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>//
For t2, V will be pointing at s2</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.98in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.98in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>//
Alternatively use the Scheduler method:</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.98in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2> Sensor_data&
V1 = *((sensor_data*) ts.currentLts());</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.98in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.98in; text-indent: 0.49in; margin-bottom: 0in">
…</P>
<P CLASS="western" STYLE="margin-left: 0.98in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2> V.distance
= <calculate your values here>;</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.98in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>}</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.98in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<OL START=3>
<LI><P CLASS="western" STYLE="margin-bottom: 0in; page-break-after: avoid">
<FONT FACE="Times New Roman, serif"><B>ENABLING TASK PRIORITIZATION
</B></FONT>
</P>
</OL>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in; page-break-after: avoid">
<BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Times New Roman, serif"><FONT SIZE=2 STYLE="font-size: 11pt">In
certain cases you want a task to be invoked before others in case of
scheduling collision (tasks ready to be invoked at the same time). In
a flat execution chain scenario tasks are evaluated for execution in
the order they were added to the chain. Therefore a single task has
to wait for the rest of the chain to be evaluated to get a chance
again. </FONT></FONT>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Times New Roman, serif"><FONT SIZE=2 STYLE="font-size: 11pt">Consider
a scenario where a task taking gyroscope measurements has to be
invoked as close to the actual scheduling time as possible. That is
when task prioritization comes to help. </FONT></FONT>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Times New Roman, serif"><FONT SIZE=2 STYLE="font-size: 11pt">Let’s
say tasks t4 and t5 are taking measurements from gyroscope and
accelerometer, and tasks t1, t2 and t3 are doing something less
important.</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Times New Roman, serif"><FONT SIZE=2 STYLE="font-size: 11pt">This
is how such setup is coded:</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.98in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>#define
_TASK_PRIORITY</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.98in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>#include
<TaskScheduler.h></FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.98in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.98in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>Scheduler
r, hpr;</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.98in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.98in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>//
Tasks</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.98in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>Task
t1(1000, TASK_FOREVER, &tCallback, &r); //base priority</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.98in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>Task
t2(2000, TASK_FOREVER, &tCallback, &r);</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.98in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>Task
t3(3000, TASK_FOREVER, &tCallback, &r);</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.98in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.98in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>Task
t4(10, TASK_FOREVER, &tCallback, &hpr); // higher priority</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.98in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>Task
t5(100, TASK_FOREVER, &tCallback, &hpr); //higher priority</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.98in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.98in; margin-bottom: 0in">…</P>
<P CLASS="western" STYLE="margin-left: 0.98in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.98in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>void
setup () {</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.98in; margin-bottom: 0in">
</P>
<P CLASS="western" STYLE="margin-left: 0.98in; margin-bottom: 0in">
…</P>
<P CLASS="western" STYLE="margin-left: 0.98in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.98in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>r.setHighPriorityScheduler(&hpr);
</FONT></FONT>
</P>
<P CLASS="western" STYLE="margin-left: 0.98in; margin-bottom: 0in">
<FONT FACE="Courier New, monospace"><FONT SIZE=2>r.enableAll(true);
// this will recursively enable the higher priority tasks as well</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.98in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>}</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<OL START=3>
<LI><P CLASS="western" STYLE="margin-bottom: 0in"><FONT FACE="Times New Roman, serif"><B>FUTHER
INFROMATION</B></FONT></P>
</OL>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>Please
refer to examples, provided with TaskScheduler package for further
information and implementation options.</FONT></FONT></P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><BR>
</P>
<P CLASS="western" STYLE="margin-left: 0.49in; margin-bottom: 0in"><FONT FACE="Courier New, monospace"><FONT SIZE=2>Real
time examples of TaskScheduler are available here:</FONT></FONT></P>
<OL>
<LI><P CLASS="western" STYLE="margin-bottom: 0in"><FONT COLOR="#0000ff"><U><A HREF="http://www.instructables.com/id/APIS-Automated-Plant-Irrigation-System/"><FONT FACE="Courier New, monospace">http://www.instructables.com/id/APIS-Automated-Plant-Irrigation-System/</FONT></A></U></FONT></P>
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