interrupt help- pin B0

[Sophi]

Hi-
I'm trying to use Pin B0 on a PIC16C74A for a pushbutton switch.
Code is as follows:
/* Interrupt Routine- come here when push button switch */
#INT_EXT // interrupt on push button
rb_isr() { // set up int service routine
output_low (PIN_C5); // go high on pin C5 for testing

while(!input(PIN_B0)) // see if push button is pressed (grounded)
{
delay_ms (1); // delay for debounce
}
output_high (PIN_C5); // go low on pin C5 for testing
} //end isr_rb

And further down:
enable_interrupts(GLOBAL);
enable_interrupts(INT_EXT);
My code doesn't work- it gets stuck at enable_interrupts(GLOBAL). Any suggestions or advice?
Thanks-
Sophi

[valemike]

I notice you didn't put the following instruction in the beginning of your main() when you set up your ports:

[Sophi]

Thanks Valemike!
I did have that line but then commented it out, uncommented, my code still gets stuck-
Sophi

[valemike]

your program seems small enough. Can you post the program?

One thing i noticed is that you have the following loop in your ISR:

[Humberto]

[bfemmel]

Sophi,

Since it is happening when you enable interrupts I can think of a few things. First, do you have another interrupt that the program is getting stuck in? Is there a interrupt enabled for which there is no ISR defined. Could it be that the line you are looking at in the ISR, (PIN_B0) is already low and the ISR never leaves because the while loop test is never false?

Just thoughts, good luck.

Bruce

[asmallri]

A 1ms debouce period is way too small for debouncing a mechanical switch. If you have an oscilloscope you may want to have a look at what is happening. 20ms is a lot more realistic value.

Rgds, Andrew
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[Sophi]

Thanks to all who responded- and with helpful info for me!
Valemike- the line
ext_int_edge(H_TO_L); stayed

Andrew- good thought, I didn't check that yet but will

Bruce-
What actually fixed this code was
1) starting over on a new file (copying all the code over except the interrupt section)
2) changing the order of the functions and the interrupt. Previously I had the code ordered Functions, Interrpts, then main. Now it is interrupt, then functions...

Sophi