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/*
State change detection (edge detection)
Often, you don't need to know the state of a digital input all the
time, but you just need to know when the input changes from one state
to another. For example, you want to know when a button goes from
OFF to ON. This is called state change detection, or edge detection.
This example shows how to detect when the built-in button changes
from off to on and on to off.
To use this example, connect to the Maple using the USB serial port.
Then push the button a few times and see what happens.
created 27 Sep 2005
modified 30 Dec 2009
by Tom Igoe
Ported to the Maple 27 May 2010
by Bryan Newbold
*/
// Variables will change:
int buttonPushCounter = 0; // counter for the number of button presses
int buttonState = 0; // current state of the button
int lastButtonState = 0; // previous state of the button
void setup() {
Serial.begin(115200); // Ignored by Maple. But needed by boards using hardware serial via a USB to Serial adaptor
// initialize the button pin as a input:
pinMode(BOARD_BUTTON_PIN, INPUT);
// initialize the LED as an output:
pinMode(BOARD_LED_PIN, OUTPUT);
}
void loop() {
// read the pushbutton input pin:
buttonState = digitalRead(BOARD_BUTTON_PIN);
// compare the buttonState to its previous state
if (buttonState != lastButtonState) {
// if the state has changed, increment the counter
if (buttonState == HIGH) {
// if the current state is HIGH, then the button went from
// off to on:
buttonPushCounter++;
Serial.println("on");
Serial.print("number of button pushes: ");
Serial.println(buttonPushCounter, DEC);
}
else {
// if the current state is LOW, then the button went from
// on to off:
Serial.println("off");
}
// save the current state as the last state, for next time
// through the loop
lastButtonState = buttonState;
}
// turns on the LED every four button pushes by checking the
// modulo of the button push counter. Modulo (percent sign, %)
// gives you the remainder of the division of two numbers:
if (buttonPushCounter % 4 == 0) {
digitalWrite(BOARD_LED_PIN, HIGH);
} else {
digitalWrite(BOARD_LED_PIN, LOW);
}
}
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