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Enable Timer1 interrupt in another ISR? CCS Forum Index -> General CCS C Discussion View previous topic :: View next topic Author pe1icq

Message Enable Timer1 interrupt in another ISR? Posted: Fri Sep 29, 2006 10:41 am

Joined: 29 Aug 2005 Posts: 9

Hi, Can I setup and enable a Timer1 interrupt in another ISR? What I'm trying to accomplish is starting Timer1 in the ISR that handles the PortA change interrupts. I've tried several things but I can't get it to work. This is what I have: Code: #define INTS_PER_MINUTE 114 int8 minutes; int8 int_count;

// (4000000/(4*8*65536)) * 60

// A running minutes counter // Number of interrupts left before a minute has elapsed

#PRIORITY TIMER1,RA #INT_TIMER1 void clock_isr() {

// This function is called every time // timer 1 overflows (65535->0), which is // approximately 1.9 times per second for // this program. output_high(pin_a3); // Green LED if(--int_count==0) { ++minutes; int_count = INTS_PER_MINUTE; } if (minutes==2) { output_high(pin_a5); // delay_ms(1000); // output_low(pin_a5); }

} #INT_RA void porta_change_isr() { delay_us(250); if (!input(PIN_A4)) { disable_interrupts(INT_TIMER1); output_low(pin_a5); // Red LED } if (input(PIN_A4)) { int_count = INTS_PER_MINUTE; minutes = 0; setup_timer_1(T1_INTERNAL | T1_DIV_BY_8); set_timer1(0);

1 от 4

01.3.2007 г. 09:55

CCS :: View topic - Enable Timer1 interrupt in another ISR?

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enable_interrupts(INT_TIMER1); output_high(pin_a5); // Red LED } #use fast_io(a) input_a(); // dummy read }

I can get in an out of the RA ISR. The LED on pin_a5 goes on and off. However Timer1 does not seem to be running, and I never get into the Timer1 ISR (I.e. the debug LED on pin_a3 never goes on) What am I doing wrong? BR. //Arno newguy

Joined: 24 Jun 2004 Posts: 557 Location: Edmonton AB Canada

Posted: Fri Sep 29, 2006 11:25 am

Stupid question, but did you configure timer 1 to run? ie. Code: setup_timer_1(T1_INTERNAL|T1_DIV_BY_2);

pe1icq

Joined: 29 Aug 2005 Posts: 9

PCM programmer

Joined: 06 Sep 2003 Posts: 6775

pe1icq

Joined: 29 Aug 2005 Posts: 9

PCM programmer

Joined: 06 Sep 2003 Posts: 6775

Posted: Fri Sep 29, 2006 12:28 pm

Yes I did. It is in the #INT_RA ISR. I also tried putting it in main() but that did not make a difference.

Posted: Fri Sep 29, 2006 1:20 pm

What PIC are you using, and what's your compiler version ?

Posted: Fri Sep 29, 2006 1:51 pm

PIC16F684 and PCM compiler version 3.229 (Linux)

Posted: Fri Sep 29, 2006 2:37 pm

Can you post a main() function, with all of your setup code for the timer, and the port i/o pins, comparators, etc., ? Please show the #fuses, #use, and applicable #define statements. In other words, I want to drop the code into MPLAB and have it compile with no errors. Then I can look at it.

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01.3.2007 г. 09:55

CCS :: View topic - Enable Timer1 interrupt in another ISR?

pe1icq

Joined: 29 Aug 2005 Posts: 9

http://ccsinfo.com/forum/viewtopic.php?t=28343&highlight=inte...

Posted: Fri Sep 29, 2006 2:39 pm

Well... it would help if I would select a port for the debug LED that actually can be used as an output. RA3 isn't one of those. I swapped RA3 and RA4 and now everything is working fine. I still have one question. Do I explicitely need to clear the interrupt flags, or does the compiler take care of that for me? I now have some clear_interrupt() statements in the ISR as shown below. Are those really needed? Code: #INT_RA void porta_change_isr() { delay_ms(200); if (!input(PIN_A3)) { disable_interrupts(INT_TIMER1); output_low(pin_a5); // Red LED } if (input(PIN_A3)) { int_count = INTS_PER_MINUTE; minutes = 0; setup_timer_1(T1_INTERNAL | T1_DIV_BY_8); set_timer1(0); clear_interrupt(INT_TIMER1); enable_interrupts(INT_TIMER1); output_high(pin_a5); // Red LED } clear_interrupt(INT_RA); }

newguy

Joined: 24 Jun 2004 Posts: 557 Location: Edmonton AB Canada

Posted: Fri Sep 29, 2006 2:41 pm

Clearing the interrupt is absolutely required. The compiler doesn't take care of that for you. If a timer is enabled, it will set its overflow flag when it overflows regardless of whether its interrupt is enabled. Whoops - have to clarify. If you enable the timer interrupt, you must clear any outstanding timer interrupts. As PCM has said, no need to clear the other one - the compiler does that automatically. Last edited by newguy on Fri Sep 29, 2006 3:19 pm; edited 1 time in total

PCM programmer

Joined: 06 Sep 2003 Posts: 6775

Posted: Fri Sep 29, 2006 2:55 pm

You don't need to clear the RA interrupt flag at the end of the isr. The compiler automatically puts in a line of ASM code to do that for you. See the lines shown in bold below. Quote: .................... } .................... clear_interrupt(INT_RA); 0088: BCF 0B.0.................... } .................... .................... 0089: BCF 0B.0 008A: BCF 0A.3 008B: GOTO 02B

rnielsen

Joined: 23 Sep 2003 Posts: 430 Location: Utah

Posted: Fri Sep 29, 2006 5:09 pm

You can turn on/off a timer from anywhere in your code, including an ISR. Simply set/clear the bit that enables the timer. Ronald

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01.3.2007 г. 09:55

CCS :: View topic - Enable Timer1 interrupt in another ISR?

Neutone

Joined: 08 Sep 2003 Posts: 1104 Location: Houston

http://ccsinfo.com/forum/viewtopic.php?t=28343&highlight=inte...

Posted: Sat Sep 30, 2006 5:12 pm

pe1icq wrote: Do I explicitely need to clear the interrupt flags, or does the compiler take care of that for me? Code:

set_timer1(0); clear_interrupt(INT_TIMER1); enable_interrupts(INT_TIMER1);

That first line of code will set the counter to zero the second line will clear the interupt flag that may have already been set by an overflow of timer 1 counter. The third line will enable interupt if the timer interupt flag is set. If you dont clear the interupt flag before enabeling the interupt it might jump to the timer 1 interupt routine as soon as it leaves the RA interupt. Display posts from previous: All Posts

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