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Port B interrupt is not working with 16F1938. Help!

 
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kongfu1



Joined: 26 Apr 2010
Posts: 56

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Port B interrupt is not working with 16F1938. Help!
PostPosted: Thu Jul 21, 2011 5:57 pm     Reply with quote
This is an example code I got from PCM for 16F882. With some minor changes, it is NOT working with 16F1938.

The problem is that when an interrupt RB triggered by pushing a button, it will be triggered continuously and never stops.


Code:

#include <16F1938.h>
#fuses INTRC_IO, NOWDT, BROWNOUT, PUT, NOLVP
#use delay(clock=4000000)

#define SW_PIN   PIN_B1
#define LED_PIN  PIN_C7

int8 sleepFlag = 1;

#int_rb
void rb_isr(void)
{
   int8 value;
   
   output_toggle(LED_PIN);
   delay_ms(10);
   
   value = input(SW_PIN);
   //value = input_b( );   // even read twice, it is not working.
   if(value)
   {
      if(sleepFlag)
         sleepFlag = 0;
      else
         sleepFlag = 1;
   }
}

#INT_COMP
void Comp_int(void)
{
   sleepFlag = 0;
}

//============================
void main()
{
   int8 temp;
   
   output_low(LED_PIN);
   
   setup_comparator(CP1_A1_DAC|CP1_OUT_ON_A4|CP1_INT_H2L);
   setup_dac(DAC_VSS_VDD|DAC_OUTPUT);
   dac_write(3);

   temp = input(SW_PIN);
   clear_interrupt(INT_RB);
   enable_interrupts(INT_RB1);
   enable_interrupts(INT_COMP);
   enable_interrupts(GLOBAL);

   while(1)
   {
      delay_ms(100);
      if(sleepFlag)
         sleep();
     
   }
}


Please help. Thanks.
PCM programmer



Joined: 06 Sep 2003
Posts: 21708

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PostPosted: Fri Jul 22, 2011 3:36 pm     Reply with quote
Always post your compiler version. We don't remember your version
between posts and you might have updated it.

Also, I notice you have added all this comparator interrupt code and
DAC code. What external connections do you have on the PIC ?

Have you tested each hardware module and its code separately, and
proven that they work ? Have you tested the comparator code all
by itself in its own program ?

Before asking me for help, you need to do all this.
kongfu1



Joined: 26 Apr 2010
Posts: 56

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PostPosted: Fri Jul 22, 2011 7:05 pm     Reply with quote
PCM programmer wrote:
Always post your compiler version. We don't remember your version
between posts and you might have updated it.

Also, I notice you have added all this comparator interrupt code and
DAC code. What external connections do you have on the PIC ?

Have you tested each hardware module and its code separately, and
proven that they work ? Have you tested the comparator code all
by itself in its own program ?

Before asking me for help, you need to do all this.


Compiler version: 4.122
MPLAB:8.73
ICD: PICKit3

Comparator is working fine and analog circuit is off during my test.
Analog signal is 0-3.3V and is connected to RA1 pin.

I just did a test by removing all the code related with comparator, the result is same.

Thanks.
PCM programmer



Joined: 06 Sep 2003
Posts: 21708

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PostPosted: Sun Jul 24, 2011 5:12 pm     Reply with quote
I found two bugs. There's one bug in the compiler and one in your code.
The compiler bug (vs. 4.122) is in the start-up code. It doesn't correctly
setup all the analog pins on the PIC to be digital i/o pins. But you can
fix it by adding the line shown in bold below.
Quote:

void main()
{
int8 temp;

setup_adc_ports(NO_ANALOGS);



The 2nd bug is in your code. For the 16F1938 and related PICs, you do
not clear the "change condition" by reading port B. You have to clear
a bit in the IOCBF register for the specific pin, or you can just clear the
whole register. I show how to do this below. Add the lines in bold:
Quote:

#include <16F1938.h>
#fuses INTRC_IO, NOWDT, BROWNOUT, PUT, NOLVP
#use delay(clock=4000000)

#byte IOCBF = 0x396
#define clear_IOC_flags() IOCBF = 0


Remove (or comment out) the input(SW_PIN) line, and add the line to
clear the IOC flags as shown below:
Quote:

#int_rb
void rb_isr(void)
{
int8 value;

output_toggle(LED_PIN);
delay_ms(10);

clear_IOC_flags();
//value = input(SW_PIN);



If you do all that, I think it should work.
kongfu1



Joined: 26 Apr 2010
Posts: 56

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PostPosted: Mon Jul 25, 2011 11:29 am     Reply with quote
Hi PCM,

Thanks very much for the helps. I have talked with support of CCS. A call clear_interrupt should clear up IOCBF register. With 4.122 version, IOCBF is defined at address 0x393 instead of 0x396 for 16F1938. That is why the interrupt flag was not cleared. They have suggested same way as yours to fix it temporally. But they did not see first bug.

Thanks again.
PCM programmer



Joined: 06 Sep 2003
Posts: 21708

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PostPosted: Mon Jul 25, 2011 12:16 pm     Reply with quote
I was using the 16F1937 to test the problem in hardware. The 16F1937
has the ANSELx register bug in the start-up code. The 16F1938 does not.
The problem still exists in vs. 4.123. I emailed CCS about this today.
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