Creating a 10 second delay using ISR in TIMER1 of atmega328p - c

Question

I'm trying to create a 10 second delay using TIMER1(16 bit) in atmega328p, I don't know if the delay has been created or not because it takes longer duration than 10 seconds and expected output( which is to create pwm waves) is not obtained. Here I have created a 1second delay and looped it 10 times, TIMER0 is used for creating pwm waves.
#include <stdint.h>
#include <avr/io.h>
#include <avr/interrupt.h>
#include "interrupt.h"
#define SET_BIT(PORT,BIT) PORT |= (1<<BIT)
#define CLR_BIT(PORT,BIT) PORT &= ~(1<<BIT)
struct {
volatile unsigned int BIT: 1;
}
FLAG_TIMER;
void timer_configuration() //16 bit timer
{
TCCR1A = 0x00; // Normal mode of operation
TCNT1 = 0xC2F8;
TCCR1B |= ((1 << CS10) | (1 << CS12));
TCCR1B &= ~(1 << CS11); //101
sei(); // Global interrupt
}
void timer_on()
{
TIMSK1 |= (1 << TOIE1);
}
void pwm_configuration() //TIMER0 - 8 bit
{
TCCR0A |= ((1<<WGM00) | (1<<WGM01)); //setting it to fast PWM mode
TCCR0A |= (1<<COM0A1);
TCCR0A &= ~(1<<COM0A0);
TCNT0 = 0x00;
TCCR0B |= ((1<<CS00) | (1<<CS02)); //Prescaler setting 1024
TCCR0B &= ~(1<<CS01);
sei();
}
ISR(TIMER1_OVF_vect)
{
static unsigned int counter;
counter++;
if(counter >= 10)
{
FLAG_TIMER.BIT=1;
counter = 0;
TCNT1 = 0xC2F8;
TIMSK &= ~(1<< TOIE1);
}
else
{
FLAG_TIMER.BIT=0;
}
}
int main(void)
{
SET_BIT(DDRD,PD6); //CRO
timer_configuration();
pwm_configuration();
while(1)
{
timer_on();
if(FLAG_TIMER.BIT == 1)
{
OCR0A = 128; //50% dutycycle
}
}

Answer 1

You set the counter to 49912 on initialisation and increment your count when it overflows, but it will then start from 0, so if 15624 counts = 1 second, then your counter will increment to 10 after 15624 + 9 x 216 counts or about 38.75 seconds.
Move the TCNT1 = 0xC2F8; line in the ISR:
ISR(TIMER1_OVF_vect)
{
static unsigned int counter;
TCNT1 = 0xC2F8;
counter++;
if(counter >= 10)
{
FLAG_TIMER.BIT=1;
counter = 0;
TIMSK &= ~(1<< TOIE1);
}
else
{
FLAG_TIMER.BIT=0;
}
}
I am not familiar with ATmega, but I cannot believe that is an appropriate way to use the timer. Normally you'd up-count to a compare value with auto reset to zero, or down-count from an auto reload value to zero and let the hardware reload the counter.