Beginner in need of help !!

[robbo78]

Hi again, I have been trying to play around with interrupts, both instant asm (which barely makes any sense to me) & basic 'on interrupt'.

I have wrote a very basic code, however what I cant get my head around is how to incorporate the button method we discussed before into an interrupt? So how can one push & release of the button enter an interrupt loop & wait there, until I push & release the button again which would exit back to the main loop? Here is the small code I have written.

Thanks again,
Rob

ANSEL = 0 'digital I/O
CMCON0 = 7 'comparator off
INTCON = %00010000 'enable pin 4 interrupt
TRISIO = %00010000 'pin 4 input
 
LED VAR GPIO.0 'pin 7 led
Switch VAR GPIO.4 'pin 3 button

ON INTERRUPT GOTO int1 

main:
HIGH LED
PAUSE 500
LOW LED
PAUSE 500
GOTO main

DISABLE
int1:
TOGGLE LED
INTCON.1 = 0
RESUME
ENABLE

[HenrikOlsson]

Hi Rob,
If you want the button to enable/disable the blining LED then you can't toggle the LED itself in the interrupt and then just continue to blink it in the main program loop. What you need is flag or semaphore telling the main loop if the LED is supposed to blink or not.

BLINK VAR BIT

ON INTERRUPT GOTO int1 

main:
If Blink = 1 THEN
  HIGH LED
  PAUSE 500
  LOW LED
  PAUSE 500
ENDIF
GOTO main

DISABLE
int1:
Blink = !Blink   ' Invert the state of the semapore
RESUME
ENABLE

Please note that the PAUSE statement is basically delaying the Int1 routine from executing until the PAUSE statement finishes (that's the drawback of ON INTERRUPT). So if you push the button just as the PAUSE 500 start to exectute the ISR won't execute until 500ms later. This won't matter in this case but please keep that in mind when you start doing more complicated stuff.

Also, the above does not incorporate any debounce, you may want to add that.

/Henrik.

[robbo78]

Hi Henrik, thanks for explaing that to me it will help me a lot I am learning more & more as I go on

Rob

Hi Rob,
If you want the button to enable/disable the blining LED then you can't toggle the LED itself in the interrupt and then just continue to blink it in the main program loop. What you need is flag or semaphore telling the main loop if the LED is supposed to blink or not.

BLINK VAR BIT

ON INTERRUPT GOTO int1 

main:
If Blink = 1 THEN
  HIGH LED
  PAUSE 500
  LOW LED
  PAUSE 500
ENDIF
GOTO main

DISABLE
int1:
Blink = !Blink   ' Invert the state of the semapore
RESUME
ENABLE

Please note that the PAUSE statement is basically delaying the Int1 routine from executing until the PAUSE statement finishes (that's the drawback of ON INTERRUPT). So if you push the button just as the PAUSE 500 start to exectute the ISR won't execute until 500ms later. This won't matter in this case but please keep that in mind when you start doing more complicated stuff.

Also, the above does not incorporate any debounce, you may want to add that.

/Henrik.