mabauti

I want to going back to the same label after an interruption service ALWAYS

let´s say I have this program
How do I make an interruption service in order to go back ALWAYS to the label decisions?

Papabravo

You put the address of the label you want to return to on the stack. When you execute the return from interrupt you'll get where you want to go. I don't recommend this approach for two reasons.

1. It is completely unnecessary
2. You'll never remember what you did and why when you come bact to it in 6 months

__________________
We never have time to do it right; but we always have time to do it over.

kchriste

It can also lead to really nasty bugs. Image if you have a 32bit add routine on an 8bit processor and it is half way through dumping the answer, 8bits at a time, into a 32bit variable and your interrupt routine calls it away never to return.
Use flags to do this.

__________________
--- The days of the digital watch are numbered. ---

donniedj

In the case of no 32-bit add routine I guess its ok. Not a morality or legality thread.

I have code in products that after a certain criteria is meet in the interrupt, I must always vector to a know location period. This was not true for every time the interrupt was called but after being called a set number of times. If its need then do it, block interrupts during 32-bit routines or whenever necessary.

And whats the method of remember anything in code?

__________________
I can still log in! Delete my account and all my post now.

eblc1388

This is not a debate of why you would need to do it but how to do it.

With AVR, this is easily done as one can modify the stackpointer or push/pop values from the stack.

With 16F PIC, it is a bit more involved. You need to place(sometimes more than one) check bit instructions inside every routine and jump to "decisions" every time the bit is found set. Inside the ISR, you set that bit and return.

On start executing the "decisions" code, you reset the bit to false.

__________________
L.Chung

Nigel Goodwin

I would disagree, if he's wanting to do such completely wrong things he needs telling NOW, not after he's created loads of really badly written and unreliable code. I don't see as there's any reason to ever want to do something so potentially dangerous?.

__________________
PIC programmer software, and PIC Tutorials at:
http://www.winpicprog.co.uk

Pommie

Back in the 80s it was quite normal to have you ISR jump to the start of your main loop. Your main loop processed all the critical game stuff before updating the screen. By placing things like updating the score and radars etc near the bottom of the main loop they would get "dropped" if things got too busy. No one ever noticed if the score/radar got updated because at this point they were too busy trying to stay alive. One classic that used this technique was Defender from Williams.

Anyway, on a 16 series pic you could simply do,

The code at the destination would have to clear the interrupt flag and re enable the global interrupts. The stack is circular and so doesn't matter. I must however add, I can't think of many applications that would benefit from this technique. Edit, if the OP's different routines were LED flash sequences (or something similar) and the IRQ was to change sequence then I guess this would work.

Mike.

3v0

A more common method is to have the ISR set a flag and handle the branch back to decisions handled in the main code.

This mimics the action of a break within a loop.


You could shorten up the code with a macro or define.

__________________
search engine for electronic parts
Junebug USB PIC programmer kit., USB Bit Wacker, Homepage
The 15 Minute Printed Circuit Board! (+drill time)

Papabravo

And in that spirit I gave him the answer he was seeking along with the admonition. I feel that we have a responsibility to warn people to think about what they are doing. They can still do whatever they want -- that is the essence of freedom.

__________________
We never have time to do it right; but we always have time to do it over.

mabauti

Ok then.

Thank you for your comments gentlemen