Added LED to InputPullup example

Author: tigoe

build/shared/examples/2.Digital/DigitalIputPullup/DigitalIputPullup.ino

@@ -6,6 +6,7 @@
  
  The circuit: 
  * Momentary switch attached from pin 2 to ground 
+ * Built-in LED on pin 13
  
  Unlike pinMode(INPUT), there is no pull-down resistor necessary. An internal 
  20K-ohm resistor is pulled to 5V. This configuration causes the input to 
@@ -24,7 +25,8 @@ void setup(){
   //start serial connection
   Serial.begin(9600);
   //configure pin2 as an input and enable the internal pull-up resistor
-  pinMode(2, INPUT_PULLUP); 
+  pinMode(2, INPUT_PULLUP);
+  pinMode(13, OUTPUT); 
 
 }
 
@@ -33,9 +35,18 @@ void loop(){
   int sensorVal = digitalRead(2);
   //print out the value of the pushbutton
   Serial.println(sensorVal);
-  //brief delay
-  delay(10);
-
+  
+  // Keep in mind the pullup means the pushbutton's
+  // logic is inverted. It goes HIGH when it's pressed,
+  // and LOW when it's not. Turn on pin 13 when the 
+  // button's pressed, and off when it's not:
+  if (sensorVal == HIGH) {
+    digitalWrite(13, LOW);
+  } 
+  else {
+    digitalWrite(13, HIGH);
+  }
 }
 
 
+