Sorry, but another interrupt problem

[tbirchall]

I'm a newbie just can't seem to get this working. I've checked the other posts but I don't see what I'm doing wrong. I'm trying to receive an interrupt from push button connected to portb/0. I am using a PIC16F84A and here is the code:

Include "modedefs.bas"

CLEAR
LOW 7

TRISB.0 = 1
INTCON = %10010000
ON INTERRUPT GOTO handleInterrupt

main:
PAUSE 1
GOTO main

DISABLE
handleInterrupt:

HIGH 7 ' turn on LED so I know it worked
PAUSE 1000
LOW 7

INTCON.1 = 0
RESUME

ENABLE

END

If the problem isn't in the code, it might also be how I've got the push button hooked up. (Like I said, I'm a newbie.) I've tried several things, but right now I have one lead on the push button connected to 5v+ and the other lead connected to portb/0. I've tested the LED and switch separately, and they both work and the code compiles as well.

Any help is GREATLY appreciated.

[mister_e]

what else on the PORTB.0 pin??? any pull-down resistor???
Should have one, if not it could act weird.

Another altenative is to use the internal PULL-UP and connect your push-buuton between RB0 and GND

OPTION_REG = 0 ' enable internal pull-up and interrupt on RB0 falling edge

[Yuantu Huang]

You should initialise the INTEDG bit of OPTION_REG. If you would like to make falling edge interrupt, just add OPTION_REG.6 = 0 after INTCON = %10010000

[mister_e]

This is why i suggest my previous. BTW in the first post PB was connected to VCC and OPTION_REG.6 is set to 1 at start-up wich is already rising edge.

[tbirchall]

Thank you very much. That did the trick. It is really great to have such knowledgable people to turn to. Thanks for taking the time.

-Tom

[tbirchall]

OK, I hate to be a pest but... I got the sample code working, but when I apply it to my real code, it only works once. Basically, what I'm trying to achieve is to have the program wake on interrupt, do something, then go back to napping. This is to save power since it is a battery powered project. So, my loop looks like this:

loop:
NAP 0
PAUSE 1

GOSUB blah
GOTO loop

The idea is that all the interrupt does is to clear the flag, then the code will resume at the next line of code - in this case, the PAUSE statement. If I have a simple HIGH/LOW FOR/NEXT loop that lights an LED, it works perfectly over and over again. If I have my gosub (like above), then it works once and that's it - the interrupt never gets called again. Can someone tell me conceptually what is going on? My gosub has one other gosub nested in it, so I don't think it is too deep. Oh, and blah does have a return and my interrupt routine is wrapped in DISABLE and ENABLE calls. Thank you!

-Tom

[Melanie]

Whilst I prefer to use @SLEEP rather than NAP, I did once experience an anomaly (about three years back - probably PBP v2.42) whereby a couple of instructions following the @SLEEP were not executed properly. I cured the problem (without investigating further due to lack of time) by inserting half a dozen @NOP statements before I resumed with any proper code... the reasoning behind that was if it was going to misbehave and skip a couple instructions then the NOP's would absorb the anomaly and contine as it was intended. Anyhow, it worked for me, might be worth trying to see if it does it for you.