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wind
Guest
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| RTCC interrupt won't stop?? |
 Posted: Tue Oct 09, 2007 9:10 pm |
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Hi all, i have problems with interrupt again. i'm using PIC16F877, ccs 4.049, using interrupt to send pulse to stepper. My goal is to make the motor rotate 3 revolutions and stop, but what happen now is, the motor keeps rotating. I think it should be my coding problem, I need some guides, thanks a lot.
| Code: | #include <16F877>
#fuses XT, NOWDT, NOPROTECT, BROWNOUT, PUT, NOLVP
#use delay(clock = 20000000)
#define PWM_PIN PIN_B1
int8 i;
short rtcc_flag; //declare global flag variable
#INT_RTCC
void rtcc_isr(void);
int8 iCounter=0;
//---------------------------
void main()
{
rtcc_flag = FALSE;
setup_counters(RTCC_INTERNAL,RTCC_DIV_2);
enable_interrupts(INT_RTCC);
enable_interrupts(GLOBAL);
while(1)
{
if(iCounter<3) //counter for 3 revolutions
{
if(rtcc_flag == TRUE)
{
for(i=0; i<1000; i++) //1000 steps = 1 revolution
{
output_high(PIN_B1);
delay_us(450);
output_low(PIN_B1);
delay_us(450);
rtcc_flag = FALSE;
}
}
}
else
{
output_low(PIN_B1);
}
}
}
//====================================
#INT_RTCC
void rtcc_isr(void)
{
rtcc_flag = TRUE;
iCounter++;
}
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Ttelmah
Guest
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| Posted: Wed Oct 10, 2007 2:39 am |
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Two separate problems.
Remember conters will wrap. Your 'icounter' value, will be <3, for 3/256th of the time, whatever else is going on. It'll count 0,1,2,3.......252,253,254,255,0,1,2,3....
Rtcc_flag, will always end up true (you are setting it 'true' in the interrupt), so only a few uSec after you set it false, it'll be true again.
As it stands, the RTCC interrupt will trigger every 512 instruction times, so you will get the three movements forward, then a pause of 129536 processor instruction cycles (253 counts 512 instruction cycles/count), which at 20MHz, is 1/38th of a second, and then it'll do three movement cycles again.
Consider something like:
| Code: |
#INT_RTCC
void rtcc_isr(void)
{
if (icounter<3) {
rtcc_flag = TRUE;
iCounter++;
}
}
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This way, the increment, will stop when the count gets to 3.
To restart, all you do in the 'main', is set icounter to zero.
Best Wishes |
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wind
Guest
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| it's working !!! it's working ~~~ |
| Posted: Thu Oct 11, 2007 7:05 pm |
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Thanks Ttelmah. I got my desired result by referring to your solution. Thanks a lot.
Following is my working code, i am not sure whether it is 100% correct or not, well, at least it stops. LOL ~~ 
| Code: | #include <16F877>
#fuses XT, NOWDT, NOPROTECT, BROWNOUT, PUT, NOLVP
#use delay(clock = 20000000)
#define PWM_PIN PIN_B1
#define RTCC_PRELOAD (64 - 39)
int8 iCounter=0;
int16 i=0;
short rtcc_flag;
#INT_RTCC
void rtcc_isr(void);
//---------------------------
void main()
{
rtcc_flag = FALSE;
setup_counters(RTCC_INTERNAL,RTCC_DIV_2);
enable_interrupts(INT_RTCC);
enable_interrupts(GLOBAL);
while(1)
{
if(iCounter<5 && rtcc_flag == TRUE)
{
output_high(PIN_D5);
for(i=0; i<1000; i++) //1000 steps = 1 revolution
{
delay_us(180);
output_high(PIN_B1);
delay_us(55);
output_low(PIN_B1);
delay_us(55);
}
iCounter++; //increment for revolution counter
}
else
{
delay_us(800);
output_low(PIN_D5);
disable_interrupts(INT_RTCC);
}
}
}
//====================================
#INT_RTCC
void rtcc_isr(void)
{
rtcc_flag = TRUE;
}
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