Task 31B -- Making Use of Interrupts

..
Again the schematic is from the Code Project/Interrupts site.

(I had to use a 150Ohm resistor because i couldn't find my push-switch!
  It didn't work quite as well - i should really find that switch! - but i
  suspect my wobbly hand had a lot to do with it; i could try 'de-bouncing'
  the 'switch', but delay() won't work inside the interrupt-triggered function  
  (find the switch, stoopid!)  )


This time, however,  the code makes use of a Hardware Interrupt, as follows:


/*
 * Project:     Interrupts_part_B_621task31
 * Author:     DaveAuld, tidied (not much! :-) ) by Jane-Maree Howard
 * Date:          23 Feb 2010
 * Platform:   Arduino 22
 * Purpose:    To demonstrate a simple interrupt-triggered LED-switch
 * Operation:  Description:
 *             "Set up the Arduino as per the schematic
 *              and upload the code below to the microprocessor.
 *              We will use the same schematic diagram and
 *              modify the code to make use of hardware interrupts.
 *              Now when you upload the code, the LED changes state
 *              whenever the button is pressed
 *              even though the code is still running the same long delay
 *              in the main loop.
 *              [This is code PART B in the downloaded source file.]"
 */
int pbIn = 0;                               // Interrupt 0 is on DIGITAL PIN 2!
int ledOut = 4;                           // The output LED pin
volatile int state = LOW;      // The input state toggle

void setup()
{
  // Set up the digital pin 2 to an Interrupt and Pin 4 to an Output
  pinMode(ledOut, OUTPUT);

  //Attach the interrupt to the input pin and monitor for ANY Change
  attachInterrupt(pbIn, stateChange, CHANGE);
}//setup()

void loop()
{
  //Simulate a long running process or complex task
  for (int i = 0; i < 100; i++)
  {
    // do nothing but waste some time
    delay(50); // Jane-Maree increases delay time from 10ms to 50ms
  }//for()
}//loop()

void stateChange()
{
  state = !state;
  digitalWrite(ledOut, state);
}//stateChange()
//END