variable value keeps being "0" even after assigning it a value - c

Question

I'm trying to make a function to make a delay in ATmega32 using Timer0 but I can't get the delay right and when I used debugging I found that the variable T_tick is not changing value from 0 but other operations depend on its value so nothing is working right. I don't know what's wrong with this variable and I've been stuck here for while so please help.
My code is as follows in a single page:
#include <math.h>
#include "registers.h"
#define CPU_frequency 1000000
#define set_bit(x,Bit_num) x|=(1<<Bit_num)
#define clr_bit(x,Bit_num) x&=~(1<<Bit_num)
#define tolge(x,Bit_num) x^=(1<<Bit_num)
//timer configuration
#define Normal 'N'
#define PWM_paseCorrect 'O'
#define PWM_fast 'p'
#define CTC 'Q'
double T_tick = 0,T_maxDelay = 0;
uint32_t overflowsNumber = 0, T_initValue = 0, overflowCounter = 0;
// set the timer mood
void timer0_init(uint8_t timerMood)
{
switch(timerMood)
{
case Normal:
TCCR0 = 0x00;
break;
case PWM_paseCorrect:
TCCR0 = 0x40;
break;
case CTC:
TCCR0 = 0x08;
break;
case PWM_fast:
TCCR0 = 0x48;
break;
}
}
void delayT0(double delay)
{
//convert delay to Ms
delay= delay/1000;
//calculate tick time
T_tick = 1/CPU_frequency;
//calculate max delay time
T_maxDelay = 256*T_tick;
//calculate overflow flag count
overflowsNumber = ceil(delay/T_maxDelay);
//calculate the timer initial value
T_initValue = 256 - (delay/T_tick)/overflowsNumber;
//set timer initial value
TCNT0 = T_initValue;
//start timer in no prescaling mood
set_bit(TCCR0,0);
//Make a loop to count the overflows
overflowCounter = 0;
while (overflowCounter < overflowsNumber)
{
//wait until overflow flag =1
while ((TIFR &(1<<0)) == 0)
//clear overflow flag
set_bit(TIFR,0);
overflowCounter++;
}
overflowCounter = 0;
TCCR0 = 0x00;
}
void LED_init(uint8_t pinNumber)
{
set_bit(DDRA,pinNumber);
}
void LED_TOGLE(uint8_t pinNumber)
{
tolge(PORTA,pinNumber);
}
int main(void)
{
LED_init(0);
timer0_init(Normal);
while (1)
{
LED_TOGLE(0);
delayT0(512);
}
}
The delay is supposed to be 512ms but it's only 1ms because of the variable T_tich that i don't know what's its problem; or that's what i think.
if any one can help please do; i've been stuck in there for too long

Answer 1

your problem is so simple :
in the line T_tick = 1 / CPU_frequency;. after preprocessing , it's expanded to be equivalent to : T_tick = 1 / 1000000; which will always result in zero.
even my compiler gives me this warning in this line :
Clang-Tidy: Result of integer division used in a floating point context; possible loss of precision
as the right hand side is integer division as 1 / 1000000 = 0
so T_tick = 0; , that's why T_tick will be always zero.
so either write T_tick = 1.0 / CPU_frequency; or T_tick = (double)1 / CPU_frequency;.
also don't forget to turn on all your compiler warnings using compiler flags as it will really help.