button: revise, get compiling via the GUI

big-button/button.pde

@@ -1,90 +1,42 @@
-/* 
- Debounce
- 
- Each time the input pin goes from LOW to HIGH (e.g. because of a push-button
- press), the output pin is toggled from LOW to HIGH or HIGH to LOW.  There's
- a minimum delay between toggles to debounce the circuit (i.e. to ignore
- noise).  
- 
- The circuit:
- * LED attached from pin 13 to ground
- * pushbutton attached from pin 2 to +5V
- * 10K resistor attached from pin 2 to ground
- 
- * Note: On most Arduino boards, there is already an LED on the board
- connected to pin 13, so you don't need any extra components for this example.
- 
- 
- created 21 November 2006
- by David A. Mellis
- modified 30 Aug 2011
- by Limor Fried
- modified 28 Dec 2012
- by Mike Walters
- 
- This example code is in the public domain.
- 
- http://www.arduino.cc/en/Tutorial/Debounce
+/* -*- mode: c -*-
+Based on  http://www.arduino.cc/en/Tutorial/Debounce
  */
 
-// constants won't change. They're used here to 
-// set pin numbers:
+// Constants
 const int buttonPin = 2;    // the number of the pushbutton pin
 const int ledPin = 13;      // the number of the LED pin
+const long DEBOUNCE_DELAY = 50; // minimum press to be considered a press
 
-// Variables will change:
-int ledState = HIGH;         // the current state of the output pin
-int buttonState;             // the current reading from the input pin
-int lastButtonState = LOW;   // the previous reading from the input pin
-
-// 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.
+// Variables
+int down = HIGH; // is the button down (LOW) or up (HIGH)
 long lastDebounceTime = 0;  // the last time the output pin was toggled
-long debounceDelay = 50;    // the debounce time; increase if the output flickers
 
 void setup() {
   pinMode(buttonPin, INPUT);
   pinMode(ledPin, OUTPUT);
 
   // set initial LED state
-  digitalWrite(ledPin, ledState);
-  Serial.begin(9600)
+  digitalWrite(ledPin, LOW);
+  Serial.begin(9600);
 }
 
 void loop() {
-  // read the state of the switch into a local variable:
-  int reading = digitalRead(buttonPin);
-
-  // check to see if you just pressed the button 
-  // (i.e. the input went from LOW to HIGH),  and you've waited 
-  // long enough since the last press to ignore any noise:  
-
-  // If the switch changed, due to noise or pressing:
-  if (reading != lastButtonState) {
-    // reset the debouncing timer
-    lastDebounceTime = millis();
-  } 
-
-  if ((millis() - lastDebounceTime) > debounceDelay) {
-    // whatever the reading is at, it's been there for longer
-    // than the debounce delay, so take it as the actual current state:
-
-    // if the button state has changed:
-    if (reading != buttonState) {
-      buttonState = reading;
-
-      // only toggle the LED if the new button state is HIGH
-      if (buttonState == HIGH) {
-        ledState = !ledState;
-	Serial.println("click");
-      }
-    }
+  int is_pushed = digitalRead(buttonPin) == HIGH;
+  int is_down = down == LOW;
+  long now = millis();
+
+  if (is_pushed && !is_down){
+    down = LOW;
+    lastDebounceTime = now;
+    digitalWrite(ledPin, HIGH);
+  }
+  else if (!is_pushed && is_down) {
+    down = HIGH;
+    digitalWrite(ledPin, LOW);
+    // were we down long enough to be considered a push?
+    long duration = (now - lastDebounceTime);
+    if(duration > DEBOUNCE_DELAY){
+      Serial.println(duration);
+    } 
   }
-
-  // set the LED:
-  digitalWrite(ledPin, ledState);
-
-  // save the reading.  Next time through the loop,
-  // it'll be the lastButtonState:
-  lastButtonState = reading;
 }