How to know what pin triggered an interrupt?

[mackrackit]

I may be wrong, but I can not think of a PIC that has a porta interrupt.

What PIC are you using?

[Bruce]

I would read the port as fast as possible (immediately on interrupt) by saving it in an 8-bit
variable, and then testing for the port bit in question stored in my variable.

MyPort VAR BYTE. MyPort=PORTA. Now test bits in MyPort for the change.

Edit:
The only interrupt flags available are those shown in the data sheet.

[xnihilo]

I would read the port as fast as possible (immediately on interrupt) by saving it in an 8-bit
variable, and then testing for the port bit in question stored in my variable.

MyPort VAR BYTE. MyPort=PORTA. Now test bits in MyPort for the change.

Edit:
The only interrupt flags available are those shown in the data sheet.

That's exactly what I'm doing (see my code below) but I have the feeling it makes me waste some time doing all the stuff only to know which pin triggered the int

DISABLE 				'disable individual interrupts while executing the interrupt routine (do not put check interrupts calls after each instruction)


in_sig: 


'MEMO: first read the port THEN clear the flag otherwise mismatch still exists
'Contribution from: Darrel Taylor (www.picbasic.co.uk/forum/)
a = porta               'read port to clear mismatch

'TEST block
HIGH portc.2

'check what pin triggered the int
'we have the time of the header pulse to manage that work
if (a.0(0) == 0) THEN
    pin = 0
    GOTO got_pin        'bypass 
ENDIF
if (a.0(1) == 0) THEN
    pin = 1
    GOTO got_pin        'bypass 
ENDIF
if (a.0(2) == 0) THEN
    pin = 2
    GOTO got_pin        'bypass 
ENDIF
if (a.0(3) == 0) THEN
    pin = 3
    GOTO got_pin        'bypass 
ENDIF
if (a.0(4) == 0) THEN
    pin = 4
    GOTO got_pin        'bypass 
ENDIF

got_pin:

This works, then I have to use porta.0(pin).

[rmteo]

I may be wrong, but I can not think of a PIC that has a porta interrupt...

Unless he is using a PIC24 - which can have interrupts on every port.

[Bruce]

If PBP supported the 24 series it would be nice..;o}

[xnihilo]

Unless he is using a PIC24 - which can have interrupts on every port.

PORTA and PORTB have it. You can choose which pin change can trigger an int but then you only have an INT flag that tells you some port pin triggered an int, it's up to us to check which one did it.

[xnihilo]

I may be wrong, but I can not think of a PIC that has a porta interrupt.

What PIC are you using?

Yes, it is called portA on change interrupt, there are also portB on change interrupts.
It exists on the models I'm using: 16F684, 16F690, 18F452. Very useful by the way.