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diff --git a/docs/esp8266/tutorial/pwm.rst b/docs/esp8266/tutorial/pwm.rst deleted file mode 100644 index 17f8ede35..000000000 --- a/docs/esp8266/tutorial/pwm.rst +++ /dev/null @@ -1,87 +0,0 @@ -Pulse Width Modulation -====================== - -Pulse width modulation (PWM) is a way to get an artificial analog output on a -digital pin. It achieves this by rapidly toggling the pin from low to high. -There are two parameters associated with this: the frequency of the toggling, -and the duty cycle. The duty cycle is defined to be how long the pin is high -compared with the length of a single period (low plus high time). Maximum -duty cycle is when the pin is high all of the time, and minimum is when it is -low all of the time. - -On the ESP8266 the pins 0, 2, 4, 5, 12, 13, 14 and 15 all support PWM. The -limitation is that they must all be at the same frequency, and the frequency -must be between 1Hz and 1kHz. - -To use PWM on a pin you must first create the pin object, for example:: - - >>> import machine - >>> p12 = machine.Pin(12) - -Then create the PWM object using:: - - >>> pwm12 = machine.PWM(p12) - -You can set the frequency and duty cycle using:: - - >>> pwm12.freq(500) - >>> pwm12.duty(512) - -Note that the duty cycle is between 0 (all off) and 1023 (all on), with 512 -being a 50% duty. If you print the PWM object then it will tell you its current -configuration:: - - >>> pwm12 - PWM(12, freq=500, duty=512) - -You can also call the ``freq()`` and ``duty()`` methods with no arguments to -get their current values. - -The pin will continue to be in PWM mode until you deinitialise it using:: - - >>> pwm12.deinit() - -Fading an LED -------------- - -Let's use the PWM feature to fade an LED. Assuming your board has an LED -connected to pin 2 (ESP-12 modules do) we can create an LED-PWM object using:: - - >>> led = machine.PWM(machine.Pin(2), freq=1000) - -Notice that we can set the frequency in the PWM constructor. - -For the next part we will use timing and some math, so import these modules:: - - >>> import time, math - -Then create a function to pulse the LED:: - - >>> def pulse(l, t): - ... for i in range(20): - ... l.duty(int(math.sin(i / 10 * math.pi) * 500 + 500)) - ... time.sleep(t/1000) - -You can try this function out using:: - - >>> pulse(led, 50) - -For a nice effect you can pulse many times in a row:: - - >>> for i in range(10): - ... pulse(led, 20) - -Remember you can use ctrl-C to interrupt the code. - -Control a hobby servo ---------------------- - -Hobby servo motors can be controlled using PWM. They require a frequency of -50Hz and then a duty between about 40 and 115, with 77 being the centre value. -If you connect a servo to the power and ground pins, and then the signal line -to pin 12 (other pins will work just as well), you can control the motor using:: - - >>> servo = machine.PWM(machine.Pin(12), freq=50) - >>> servo.duty(40) - >>> servo.duty(115) - >>> servo.duty(77) |