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[on:]

Hello forum goers,

I'm trying to create a code to interpret the output of a Vishay receiver. i.e. code that measures the length of a pulse (but I don't want to use PulseIn). I initially wrote a big long code that would interpret it all for me, but I'm having trouble making it go into the interrupt so I reduced my code down to:

#include <avr/io.h>
#include <avr/interrupt.h>

ISR(TIMER1_CAPT_vect) {
  Serial.print("G");
}

void setup()
{
  Serial.begin(9600);
  pinMode(8, INPUT);
 
  TCCR1A = 0x00;     //not using PWM
  TCCR1B = 0x01;     //no prescaling
  TIMSK1 = _BV(ICIE1); // enable input capture interrupt
}

void loop()
{
  Serial.print("L");
  delay(100); //so we're not overwhelmed with values
}

So that all I'm trying to do is get the program to enter the interrupt and print "G" (I know, I know, shouldn't print from an interrupt) at the moment. Does this seem right? It's only printing me a line of Ls, not a G in sight.
I'm testing it with a 2Hz, 5 V peak to peak square wave signal.

Thanks in advance! I've only just started using Arduino.
Claire

[Reply #1 on:]

Pins 2 & 3 are  the hardware interrupt pins, you attach an interrupt to them.
I don't see that happening with your code (but I'm not much into the register stuff either).
What is pin 8 supposed to be doing?

[Reply #2 on:]

Here's a collection of the bits I used in an RF remote control - push a button, create an interrupt.

Code:

//***************************************************
// *  Name:        pin2Interrupt, "ISR" to run when interrupted in Sleep Mode
void pin2Interrupt()
{
  g_flag = 1;
}

Code:

byte g_flag;

void setup() {
  pinMode(pin2, INPUT);                 // our sleep interrupt pin
  digitalWrite(pin2, HIGH);            //enable internal pullup resistor - pin going low causes interrup
  attachInterrupt(0, pin2Interrupt, LOW);  // ready to be interrupted
}

Code:

void loop(){

If (g_flag == 0){
Serial.print ('L');
}
else {
detachInterrupt(0);                 //disable interrupts while printing
Serial.print ('G');
g_flag = 0;   // reset the interrupt flag
 attachInterrupt(0, pin2Interrupt, LOW);   // ready for next interrupt
}
}

If you can get that working, then you will see a G on each rising edge.
Next you can change it to have the ISR be
g_flag = 1-g_flag;
and not clear g_flag with the serialprint, but hold it,
and let the state will change in the interrupt  1-0-1-0  with each edge.

Then, add stuff to capture the time when the g_flag changes.