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74 lines
2.2 KiB
Plaintext
74 lines
2.2 KiB
Plaintext
/*
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Debounce
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Each time the input pin goes from LOW to HIGH (e.g. because of a push-button
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press), the output pin is toggled from LOW to HIGH or HIGH to LOW. There's
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a minimum delay between toggles to debounce the circuit (i.e. to ignore
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noise).
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The circuit:
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* LED attached from pin 13 to ground
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* pushbutton attached from pin 7 to +5V
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* 10K resistor attached from pin 7 to ground
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* Note: On most Arduino boards, there is already an LED on the board
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connected to pin 13, so you don't need any extra components for this example.
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created 21 November 2006
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by David A. Mellis
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modified 17 Jun 2009
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by Tom Igoe
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http://www.arduino.cc/en/Tutorial/Debounce
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*/
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// constants won't change. They're used here to
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// set pin numbers:
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const int buttonPin = 7; // the number of the pushbutton pin
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const int ledPin = 13; // the number of the LED pin
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// Variables will change:
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int ledState = HIGH; // the current state of the output pin
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int buttonState; // the current reading from the input pin
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int lastButtonState = LOW; // the previous reading from the input pin
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// the follow variables are long's because the time, measured in miliseconds,
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// will quickly become a bigger number than can be stored in an int.
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long lastDebounceTime = 0; // the last time the output pin was toggled
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long debounceDelay = 200; // the debounce time, increase if the output flickers
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void setup() {
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pinMode(buttonPin, INPUT);
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pinMode(ledPin, OUTPUT);
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}
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void loop() {
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buttonState = digitalRead(buttonPin);
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// check to see if you just pressed the button
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// (i.e. the input went from LOW to HIGH), and you've waited
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// long enough since the last press to ignore any noise:
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if ((buttonState == HIGH) &&
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(lastButtonState == LOW) &&
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(millis() - lastDebounceTime) > debounceDelay) {
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// toggle the output
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if (ledState == HIGH) {
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ledState = LOW;
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} else {
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ledState = HIGH;
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}
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// ... and store the time of the last button press
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// in a variable:
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lastDebounceTime = millis();
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}
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// set the LED using the ledState variable:
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digitalWrite(ledPin, ledState);
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// save the buttonState. Next time through the loop,
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// it'll be the lastButtonState:
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lastButtonState = buttonState;
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}
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