build/shared/dist/examples/Digital/Button/Button.pde

@@ -1,27 +1,54 @@
 /*
- * Button
- * by DojoDave <http://www.0j0.org>
- *
- * Turns on and off a light emitting diode(LED) connected to digital  
- * pin 13, when pressing a pushbutton attached to pin 7. 
- *
- * http://www.arduino.cc/en/Tutorial/Button
+  Button
+ 
+ Turns on and off a light emitting diode(LED) connected to digital  
+ pin 13, when pressing a pushbutton attached to pin 7. 
+ 
+ 
+ The circuit:
+ * LED attached from pin 13 to ground 
+ * pushbutton attached to pin 7 from +5V
+ * 10K resistor attached to pin 7 from ground
+ 
+ * Note: on most Arduinos there is already an LED on the board
+ attached to pin 13.
+ 
+ 
+ created 2005
+ by DojoDave <http://www.0j0.org>
+ modified 17 Jun 2009
+ by Tom Igoe
+ 
+  http://www.arduino.cc/en/Tutorial/Button
  */
 
-int ledPin = 13;                // choose the pin for the LED
-int inputPin = 2;               // choose the input pin (for a pushbutton)
-int val = 0;                    // variable for reading the pin status
+// constants won't change. They're used here to 
+// set pin numbers:
+const int buttonPin = 7;     // the number of the pushbutton pin
+const int ledPin =  13;      // the number of the LED pin
+
+// variables will change:
+int buttonState = 0;         // variable for reading the pushbutton status
 
 void setup() {
-  pinMode(ledPin, OUTPUT);      // declare LED as output
-  pinMode(inputPin, INPUT);     // declare pushbutton as input
+  // initialize the LED pin as an output:
+  pinMode(ledPin, OUTPUT);      
+  // initialize the pushbutton pin as an input:
+  pinMode(buttonPin, INPUT);     
 }
 
 void loop(){
-  val = digitalRead(inputPin);  // read input value
-  if (val == HIGH) {            // check if the input is HIGH
-    digitalWrite(ledPin, LOW);  // turn LED OFF
-  } else {
-    digitalWrite(ledPin, HIGH); // turn LED ON
+  // read the state of the pushbutton value:
+  buttonState = digitalRead(buttonPin);
+
+  // check if the pushbutton is pressed.
+  // if it is, the buttonState is HIGH:
+  if (buttonState == HIGH) {     
+    // turn LED on:    
+    digitalWrite(ledPin, HIGH);  
+  } 
+  else {
+    // turn LED off:
+    digitalWrite(ledPin, LOW); 
   }
 }