Help! My 'interupt', erhm ...only interupts the one time?!!!

[HankMcSpank]

Many thanks for the reply.

I understand what you are saying - ie that the interupt, must not loop......therefore when the interupt button/switch is pressed, the program must jump to the interupt service routine, do something non loopy & return to the main program cleanly?

This is causing me real headaches!

As I say, I am new to programming... if the interupt service routine only allows say the changing of a status bit (or the contents of a variable), then that must mean my main program needs to check (poll) the status bit (or variable) at regular intervals to see if anything has changed - which surely kind of negates the purpose of an interupt?!

To strip this back to the barebones ....all I seek is an interupt driven on off switch .....ie 'on' & my program runs, 'off' & my program waits. I can't be the first to want such basic functionality....has anyone done/seen some example code they can link me to?

[Jerson]

You understood the concept very well. Now, whether you use a RTOS or just plain vanilla coding with interrupts, you will almost always end up using signals(messages in rtos) to indicate occurance of events. Now, that said, the microcontroller executes several instructions every second and appear to happen nearly in synch with your input (unless you are superhuman ) Due to that, even though you are polling for an event in the main loop, you will capture it within a few 100uS of your switch operating. You might even be able to capture the switch bounce if your code is optimum. So, do not fear, give it a roll and let us know if it helped.

Another option is to use the BUTTON command of PBP in a tight main loop to decide if you need to run your routine. Use no interrupts at all.

[HankMcSpank]

Many thanks Jerson

(btw I used your ISR - much easier on the eye & it works a treat!)


One other quick question (to the forum in general) - I have the need for two more external momentary push switches to interface with my program ...I'd also like to use interupts with these - what other input pins can I use? (I've now used the INT_INT pin ...which is an external interupt), but to my untrained eye, it's not easy to establish which other PIC pins would be good contenders.

I'm using a 16F690.

[Kamikaze47]

Many thanks Jerson

(btw I used your ISR - much easier on the eye & it works a treat!)


One other quick question (to the forum in general) - I have the need for two more external momentary push switches to interface with my program ...I'd also like to use interupts with these - what other input pins can I use? (I've now used the INT_INT pin ...which is an external interupt), but to my untrained eye, it's not easy to establish which other PIC pins would be good contenders.

I'm using a 16F690.

You could use the PORTB change interrupt which will trigger any time PORTB is changed, and have code in the interrupt handler that checks to see which pin(s) were pulled low (or high depending on if you are using pull up or pull down resistors).

Is it extremely time dependant that you need an interrupt? I almost never use interrupts for buttons because polling is generally just as good because of the fact that a human is pushing the button and therefore exact timing is out the window anyway.