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Problem with Timer1 [SOLVED]

 
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lcs



Joined: 10 Mar 2020
Posts: 6

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Problem with Timer1 [SOLVED]
PostPosted: Wed Jul 01, 2020 2:11 pm     Reply with quote
Hello everyone, i tried to use timer1 module of pic, but isn't work.

I tried to make a blink led with 1Hz of frequency:

t = (4 * 8 * (65536-65411)) / 4.10^6 = 1ms

Code:

#include <16f676.h>

#FUSES NOMCLR
#FUSES NOWDT
#FUSES NOPROTECT
#FUSES NOBROWNOUT
#FUSES NOCPD
#FUSES XT

#USE delay(clock=4MHz)

int ticks =0;

#INT_TIMER1
void TIMER1_tick(){
set_timer1(65411);
ticks ++;
 if (ticks >= 1000){
 OUTPUT_toggle(PIN_A0);
 ticks = 0;
 }
//clear_interrupt(INT_TIMER1);
}

void main(){
set_tris_A(0);
set_tris_C(0);
output_a(0);
set_timer1(65411);
setup_timer_1(T1_INTERNAL|T1_DIV_BY_8);
clear_interrupt(INT_TIMER1);
enable_interrupts(INT_TIMER1);
enable_interrupts(GLOBAL);
 while(true){
 }
}

Hardware:
Led => Pin A0
Crystal 4MHz and 33pF caps => OSC1-2

1) Would it be a problem related to fuses?
2) "clear_interrupt()" is necessary on timer1_isr? (same as "T1IF = 0"?)

Thanks!

Last edited by lcs on Wed Jul 01, 2020 2:33 pm; edited 1 time in total
dluu13



Joined: 28 Sep 2018
Posts: 395
Location: Toronto, ON

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PostPosted: Wed Jul 01, 2020 2:21 pm     Reply with quote
One issue I can immediately see is that you are using int for your ticks, which is an 8 bit value. That only will go up to 255 and then roll over to zero. Therefore you never reach 1000. You need to use int16 which will allow you to reach 65535 (unsigned).

I suggest looking at the type definitions in stdint.h which makes your types very explicit and easy to keep track of.
lcs



Joined: 10 Mar 2020
Posts: 6

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PostPosted: Wed Jul 01, 2020 2:33 pm     Reply with quote
dluu13 wrote:
One issue I can immediately see is that you are using int for your ticks, which is an 8 bit value. That only will go up to 255 and then roll over to zero. Therefore you never reach 1000. You need to use int16 which will allow you to reach 65535 (unsigned).

I suggest looking at the type definitions in stdint.h which makes your types very explicit and easy to keep track of.


AArrrgh
I forgot that "int" is int8 due to the use of other compilers.
I focused on other details and forgot the basics.
Solved. Thanks!
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