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Code Issues Releases Activity

Improvements in debounce from Limor

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This commit is contained in:
Tom Igoe 2009-07-03 22:26:41 +00:00
parent 6fef0130f4
commit abcef1dd3e
1 changed files with 23 additions and 23 deletions
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46
build/shared/dist/examples/Digital/Debounce/Debounce.pde vendored
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@ -17,8 +17,8 @@
created 21 November 2006 created 21 November 2006
by David A. Mellis by David A. Mellis
modified 17 Jun 2009 modified 3 Jul 2009
by Tom Igoe by Limor Fried
http://www.arduino.cc/en/Tutorial/Debounce http://www.arduino.cc/en/Tutorial/Debounce
@ -34,10 +34,10 @@ int ledState = HIGH; // the current state of the output pin
int buttonState; // the current reading from the input pin int buttonState; // the current reading from the input pin
int lastButtonState = LOW; // the previous reading from the input pin int lastButtonState = LOW; // the previous reading from the input pin
// the follow variables are long's because the time, measured in miliseconds, // the following variables are long's because the time, measured in miliseconds,
// will quickly become a bigger number than can be stored in an int. // will quickly become a bigger number than can be stored in an int.
long lastDebounceTime = 0; // the last time the output pin was toggled long lastDebounceTime = 0; // the last time the output pin was toggled
long debounceDelay = 200; // the debounce time, increase if the output flickers long debounceDelay = 50; // the debounce time; increase if the output flickers
void setup() { void setup() {
pinMode(buttonPin, INPUT); pinMode(buttonPin, INPUT);
@ -45,29 +45,29 @@ void setup() {
} }
void loop() { void loop() {
buttonState = digitalRead(buttonPin); // read the state of the switch into a local variable:
int reading = digitalRead(buttonPin);
// check to see if you just pressed the button // check to see if you just pressed the button
// (i.e. the input went from LOW to HIGH), and you've waited // (i.e. the input went from LOW to HIGH), and you've waited
// long enough since the last press to ignore any noise: // long enough since the last press to ignore any noise:
if ((buttonState == HIGH) &&
(lastButtonState == LOW) && // If the switch changed, due to noise or pressing:
(millis() - lastDebounceTime) > debounceDelay) { if (reading != lastButtonState) {
// toggle the output // reset the debouncing timer
if (ledState == HIGH) { lastDebounceTime = millis();
ledState = LOW; }
} else {
ledState = HIGH; if ((millis() - lastDebounceTime) > debounceDelay) {
} // whatever the reading is at, it's been there for longer
// ... and store the time of the last button press // than the debounce delay, so take it as the actual current state:
// in a variable: buttonState = reading;
lastDebounceTime = millis();
} }
// set the LED using the state of the button:
digitalWrite(ledPin, buttonState);
// set the LED using the ledState variable: // save the reading. Next time through the loop,
digitalWrite(ledPin, ledState);
// save the buttonState. Next time through the loop,
// it'll be the lastButtonState: // it'll be the lastButtonState:
lastButtonState = buttonState; lastButtonState = reading;
} }