ISR not uploading

Projects Programming
1

Hi, when I try to upload my code with both ISR(TIMER0_OVF_vect) along with ISR(TIMER1_COMPA_vect) in my arduino, it keeps in giving me an error and I do not know why. When I remove it however, it works fine with just the ISR(TIMER1_COMPA_vect). Does anyone know why? Many thanks

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

int i=0;
int r_pin = A0;
int sample_output;
int Sfreq = 1;
unsigned long Timer_count;

void setup (){
  noInterrupts();
  
  Serial.begin (9600);
  ADCSRA |= (1 << ADPS0) |  (1 << ADPS1) | (1 << ADPS2);  // ADC Prescaler of 128

// ------ For Sampling Frequency ------ //
  //set timer1 interrupt at Sfreq Hz
  TCCR1A = 0;// set entire TCCR1A register to 0
  TCCR1B = 0;// same for TCCR1B
  TCNT1  = 0;//initialize counter value to 0
  // set compare match register for 1hz increments
  OCR1A = 156;// = (16*10^6) / (Sfreq*Timer Prescaler) - 1 (must be <65536)
  // turn on CTC mode
  TCCR1B |= (1 << WGM12);
  // Set CS12 and CS11 and CS10 bits for prescaler <----
  TCCR1B |= (1 << CS12) | (1 << CS10); //-- 1024
//  TCCR1B |= (1 << CS12);               //-- 256
//  TCCR1B |= (1 << CS11) | (1 << CS10); //-- 64
//  TCCR1B |= (1 << CS11);               //-- 8
//  TCCR1B |= (1 << CS10);               //-- 1

  // enable timer COMPARE interrupt
  TIMSK1 |= (1 << OCIE1A);


// ----- Timer Overflow ----- //
  TCCR0A = 0;
  TCCR0B = 0;
  
  TCNT0 = 250;                                // preload timer (65536-16MHz/256/10Hz)
  TCCR0B |= (1 << CS00) | (1 << CS02);        // 1024 prescaler 
  TIMSK0 |= (1 << TOIE0);                     // enable timer OVERFLOW interrupt

  interrupts();
}  // end of setup

ISR(TIMER1_COMPA_vect){
// code
}
ISR(TIMER0_OVF_vect) {
// code
}

void loop (){}
2

Does it work when you comment this out: #include <SoftwareSerial.h>

Anyway, post the error message.

3

saaqib_m:
Does anyone know why? Many thanks

Yes. The Arduino core uses the Timer0 overflow interrupt for millis() and micros(), Switching to Timer2 instead of Timer0 works around the problem.

#include <SoftwareSerial.h>


int i = 0;
int r_pin = A0;
int sample_output;
int Sfreq = 1;
unsigned long Timer_count;


void setup ()
{
  noInterrupts();


  Serial.begin (9600);


  ADCSRA |= (1 << ADPS0) |  (1 << ADPS1) | (1 << ADPS2);  // ADC Prescaler of 128


  // ------ For Sampling Frequency ------ //
  //set timer1 interrupt at Sfreq Hz
  TCCR1A = 0;// set entire TCCR1A register to 0
  TCCR1B = 0;// same for TCCR1B
  TCNT1  = 0;//initialize counter value to 0
  // set compare match register for 1hz increments
  OCR1A = 156;// = (16*10^6) / (Sfreq*Timer Prescaler) - 1 (must be <65536)
  // turn on CTC mode
  TCCR1B |= (1 << WGM12);
  // Set CS12 and CS11 and CS10 bits for prescaler <----
  TCCR1B |= (1 << CS12) | (1 << CS10); //-- 1024
  //  TCCR1B |= (1 << CS12);               //-- 256
  //  TCCR1B |= (1 << CS11) | (1 << CS10); //-- 64
  //  TCCR1B |= (1 << CS11);               //-- 8
  //  TCCR1B |= (1 << CS10);               //-- 1


  // enable timer COMPARE interrupt
  TIMSK1 |= (1 << OCIE1A);




  // ----- Timer Overflow ----- //
  TCCR2A = 0;
  TCCR2B = 0;


  TCNT2 = 250;                                // preload timer (65536-16MHz/256/10Hz)
  TCCR2B |= (1 << CS20) | (1 << CS22);        // 1024 prescaler
  TIMSK2 |= (1 << TOIE2);                     // enable timer OVERFLOW interrupt


  interrupts();
}  // end of setup


ISR(TIMER1_COMPA_vect)
{
  // code
}
ISR(TIMER2_OVF_vect)
{
  // code
}


void loop () {}
4

johnwasser:
Yes. The Arduino core uses the Timer0 overflow interrupt for millis() and micros(), Switching to Timer2 instead of Timer0 works around the problem.

Hi John, thanks! That has worked perfectly!

5

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