Time Delay with condition loop.

[Eleengnrng]

Hello I am trying to get a loop to execute for 8s then exit or exit if the external interrupt is triggered the interrupt is active low. Here is what I have tried and other combinations. I am using a PIC16F877 at 20Mhz Clock; all the proper tris registers are set and interrupts. I have been able to have the loop terminate after the interrupt is triggered but cant seem to get the delay to work.

[Ttelmah]

The delay function, does not return a value, so cannot be used in a conditional test. You could do what you show with either:
[code]
do {
output_high(PIN_A4);
} while (delay_ms(8000),input(PIN_B0));
[code]

or

[code]
while (input(PIN_B0)) {
output_high(PIN_A4);
delay_ms(8000);
}
[/code]

The first will raise the pin, wait eight seconds, then test the input pin, while the latter tests the pin before starting.

Best Wishes

[Humberto]

If you want to exit the loop if the EXTernal INTerrupt is triggered, you would do
something like this:

[MikeW]

The way i do these sort of things is by having a timer isr which sets flags to signify a timing period is over. Then in the main loop, just check the timeout flag for being set. That way, you can check for your event change, be it a pin change, or interrupt change, and act accordingly.

hope this has helped.