Projects -- Interrupts

/* example of interrupt function using Arduino 22 */

int                 iPin   = 13;
volatile int  iState = LOW;

void setup()
{
  // open Serial
  Serial.begin(9600); 
  // set pin13 as OUTPUT
  pinMode(iPin, OUTPUT);
  // interrupt1 calls blink() when pin13 flip-flops
  attachInterrupt(1, blink, CHANGE);
  digitalWrite(iPin, 1);
  Serial.println("\nStart\n");
}//setup()

void loop()
{
  // delay 1 second
  delay(1000);
  // in effect, flip pin13
  Serial.println(iState);
  digitalWrite(iPin, iState);
}//loop()

void blink()
{
  // flip value to trigger interrupt
  iState = !iState;
}//blink()
//END

i have been trying to get this interrupt program to work - it doesn't alternate the way i think/assume it should.


it just changes at random, sometimes acting like a touch or proximity switch!

i'm baffled :-?



here's where the example code came from - i've modified it to produce a serial monitor output, & inserted another digitalWrite() statement in the setup to try to get the thing triggering regularly..

..but it doesn't {sigh}..