I need to know why the timer is not updating for every 1000hz in my code

[VSrin]

#include <iostm8l.h>

#include <stdio.h>

#include <string.h>

#include <stdlib.h>

#include "defs.h"

unsigned int count = 0;

@svlreg @interrupt void TIM1(void)

{

count += 1;

TIM1_SR1 &= ~(0x01);

}

main()

{

CLK_DIVR = 0x00; // Set the frequency to 16Mhz

CLK_PCKENR2 = 0x02; // clock for timer1

PC_DDR = 0x80; // direction output for led

 PC_CR1 = 0x80; // fast push pull mode

PE_DDR = 0x80; // direction output for led

 PE_CR1 = 0x80; // fast push pull mode

TIM1_PSCRH = 0x3e;

TIM1_PSCRL = 0x80;

TIM1_ARRH = 0x3e; 

TIM1_ARRL = 0x80;

TIM1_CR1 = 0x81;

TIM1_IER = 0x01;

  _asm("rim\n");

while(1)

{

if (count == 1000)

{

PE_ODR ^= 0x80;

count = 0;

}

}

}

[Tesla DeLorean]

What frequency is it clocking?

16,000,000 / (16,000 * 16,000) = 0.0625 Hz

0.0625 / 1,000

= 0.0000625 Hz, so perhaps toggle PE7 every 16000 seconds?

[VSrin]

Can you please explain this calculation?

I thought 16000000/16000 = 1000hz

1/1000 = 0.0001 seconds

So i used for variable "count" increment and compare for every 1000 times.

Please correct me if i am wrong

[Tesla DeLorean]

>>Can you please explain this calculation?

ARR and PSC both describe division counters. Arguable N-1 values, but I was illustrating scale of failure.

Clearly it is wrong, you've already stated it doesn't work as expected

Try

TIM1_PSCRH = 0x00;

TIM1_PSCRL = 0x00;

TIM1_ARRH = 0x3E; 

TIM1_ARRL = 0x7F;

[VSrin]

My timer works in this configuration but still i need to know how the calculation in the timer works,

TIM1_PSCRH = 0x00;

  TIM1_PSCRL = 0x80;

TIM1_CR1 = 0x11;

TIM1_EGR = 0x01;

TIM1_IER = 0x01;

[Tesla DeLorean]

UPDATE RATE = TIMCLK / ((PSCR+1) * (ARR+1))

[VSrin]

In the manual, it is mentioned as ***_CNT = ***_PSC/(PSCR[15:0]+1). Maybe I got confused

[VSrin]

Thank you so much, in my previous configuration I did not change the arr values according to the program. So, there was a miscalculation. Now it works. I have one small clarification where did you find the equation for timer interrupt generation? I cannot find in the reference manual, I use stm8l152c6 mcu

[Tesla DeLorean]

Counters, both for the timer, and the clock prescaler act as dividers. The math and concepts are fairly pedestrian, and diagrammed in the documentation for the timer.

In silicon the "end state" can be implemented with a comparator, so be sensing the current state is N-1, the next state can reset the count to 0

0 thru N-1 has N states.

UPDATE RATE = TIMCLK / ((PSCR+1) * (ARR+1))

UPDATE RATE = (TIMCLK / (PSCR+1)) / (ARR+1) // Alternate expression of the same math

If it is easier think of it as a factoring problem, there are multiple workable solutions

UPDATE RATE = TIMCLK / (Q * P)

or

UPDATE RATE = (TIMCLK / Q) / P

Where PSCR = Q-1 and ARR = P-1