CCS C Software and Maintenance Offers
FAQFAQ   FAQForum Help   FAQOfficial CCS Support   SearchSearch  RegisterRegister 

ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in 

CCS does not monitor this forum on a regular basis.

Please do not post bug reports on this forum. Send them to CCS Technical Support
RB interrupts on PIC16F84A

 
Post new topic   Reply to topic    CCS Forum Index -> General CCS C Discussion
View previous topic :: View next topic  
Author Message
Py
Guest
RB interrupts on PIC16F84A
PostPosted: Tue May 04, 2004 9:35 am     Reply with quote
Hello,

I'm trying to get a very simple program to work: I have a bicolor led with its serail resistor connected between A2 and A3. I want to swap its color each time an rb intrrupt occurs. I tested the color swapping without interrupts using delay_ms(), and it works fine.

Now, I've added interrupts code, and led is in an unstable state, eg it swaps colors without any reason at any time, and don't when I want it to.

Here is the code:

Code:

#include <16f84a.h>
#fuses HS,NOWDT,PUT,NOPROTECT
#use delay(clock=4000000)

SHORT INT flag = 0;

#int_rb
rb_isr()
{
  if (flag) {
    flag = 0;
  }
  else {
    flag = 1;
  }
}

void main()
{
  //PORT_B_PULLUPS(TRUE);

  enable_interrupts(GLOBAL);
  enable_interrupts(INT_RB);
 
  while (TRUE) {
    if (flag) {
      output_high(PIN_A2);   
      output_low(PIN_A3);   
    }
    else {
      output_high(PIN_A3);   
      output_low(PIN_A2);   
    }
  }
}


I tried with and without the "PORT_B_PULLUPS(TRUE);" line, and it didn't change much. My opinion is that I'm missing something about PORTB configuration for the use I want to make of it.

My testing circuitry is simple: apart the quartz, and the 2 27pF capacitors, I only have the bicolor led and it resistor between A2 and A3, and a jumper between B4 and the ground to simulate button actions.

Thanks in adavnce for any hint!
Pierre-Yves Paulus
PCM programmer



Joined: 06 Sep 2003
Posts: 21708

View user's profile Send private message

PostPosted: Tue May 04, 2004 11:22 am     Reply with quote
Quote:
My opinion is that I'm missing something about PORTB
configuration for the use I want to make of it.

You need to clear the "mismatch" condition by reading Port B.
This is mentioned in Section 3.2 (i/o ports) of the 16F84A data sheet,
which you should read.

Example:

#byte port_b = 6

#int_rb
void int_rb_isr(void)
{
char c;

// Clear the mismatch condition by reading Port B.
c = port_b;

// Put the rest of your isr code here.

}
Display posts from previous:   
Post new topic   Reply to topic    CCS Forum Index -> General CCS C Discussion All times are GMT - 6 Hours
Page 1 of 1

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum


Powered by phpBB © 2001, 2005 phpBB Group