You cannot select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
91 lines
2.4 KiB
Plaintext
91 lines
2.4 KiB
Plaintext
/*
|
|
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 a button or button changes from off to on
|
|
and on to off.
|
|
|
|
The circuit:
|
|
* pushbutton attached to pin 2 from +5V
|
|
* 10K resistor attached to pin 2 from ground
|
|
* LED attached from pin 13 to ground (or use the built-in LED on
|
|
most Arduino boards)
|
|
|
|
created 27 Sep 2005
|
|
modified 30 Dec 2009
|
|
by Tom Igoe
|
|
|
|
http://arduino.cc/en/Tutorial/ButtonStateChange
|
|
|
|
*/
|
|
|
|
// this constant won't change:
|
|
const int buttonPin = 2; // the pin that the pushbutton is attached to
|
|
const int ledPin = 13; // the pin that the LED is attached to
|
|
|
|
// 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() {
|
|
// initialize the button pin as a input:
|
|
pinMode(buttonPin, INPUT);
|
|
// initialize the LED as an output:
|
|
pinMode(ledPin, OUTPUT);
|
|
// initialize serial communication:
|
|
Serial.begin(9600);
|
|
}
|
|
|
|
|
|
void loop() {
|
|
// read the pushbutton input pin:
|
|
buttonState = digitalRead(buttonPin);
|
|
|
|
// 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
|
|
// wend 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
|
|
// wend 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.
|
|
// the modulo function gives you the remainder of
|
|
// the division of two numbers:
|
|
if (buttonPushCounter % 4 == 0) {
|
|
digitalWrite(ledPin, HIGH);
|
|
} else {
|
|
digitalWrite(ledPin, LOW);
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|