Hello,my code in below.A program that simply lights a led 4 seconds after the program is running.interrupt frequency 1000 Hz:
But why doesn't it work?
My mcu: Attiny84A
#define F_CPU 8000000UL
#include <avr/io.h>
#include <avr/interrupt.h>
#include <stdlib.h>
#include <stdio.h>
volatile unsigned int counter = 0;
ISR(TIMER0_COMPA_vect){
//interrupt commands for TIMER 0 here
counter++;
}
void timerprogram_init()
{
// TIMER 0 for interrupt frequency 1000 Hz:
cli(); // stop interrupts
TCCR0A = 0; // set entire TCCR0A register to 0
TCCR0B = 0; // same for TCCR0B
TCNT0 = 0; // initialize counter value to 0
// set compare match register for 1000 Hz increments
OCR0A = 124; // = 8000000 / (64 * 1000) - 1 (must be <256)
// turn on CTC mode
TCCR0B |= (1 << WGM01);
// Set CS02, CS01 and CS00 bits for 64 prescaler
TCCR0B |= (0 << CS02) | (1 << CS01) | (1 << CS00);
// enable timer compare interrupt
TIMSK0 |= (1 << OCIE0A);
sei(); // allow interrupts
}
int main(void)
{
/* Replace with your application code */
timerprogram_init();
DDRA|=(1<<7);
PORTA &=~ (1<<7);
while (1)
{
if(counter>4000)
PORTA |= (1<<7);
}
}
