Polling for an external pulse - logic question

Projects Programming
12

OK, then that gives another figure again ...

We will manually handle external interrupts:

ISR (INT0_vect)
 {
 PORTB = _BV (5);  // toggle pin 13
 PORTB = 0;
 }
 
void setup ()
  {
  pinMode (9, OUTPUT);
  pinMode (13, OUTPUT);
  
  // set up Timer 1
  TCCR1A = _BV (COM1A0);  // toggle OC1A on Compare Match
  TCCR1B = _BV(WGM12) | _BV(CS10) | _BV (CS12);   // CTC, scale to clock / 1024
  OCR1A =  4999;       // compare A register value (5000 * clock speed / 1024)
  
  // turn on external interrupt 0 (D2)
  EICRA |= _BV (ISC00) | _BV (ISC01);  // interrupt on leading edge
  EIMSK |= _BV (INT0);
  } // end of setup

void loop () 
{
}

719×249 27.3 KB

This time it is 1.5 uS to handle it.