JuneBug PIC18F1320 Interrupt Example

[rnorman3]

I'm new to PIC programming and found it's hard to find simple skeleton examples of how to program MCU's. I managed to piece this entire example (attached) together from the datasheet for the PIC18F1320. The code attached has a very simple example of how to get an interrupt working and some notes that might be helpful for someone starting out like me. It's built for a Junebug programmer. If any experts out there have some comments on how to improve it please do. Especially the ISR (interrupt service routine), where I tried to build an if/then style statement (if light is on turn off, if off turn on) using assembly, I think there's a better/shorter way than what I have, but can't think of it right now...

Good luck!
RN

 

[Pommie]

Well done, it's not easy doing things straight from the data sheet.

As far as your ISR goes, there is a much simpler way to achieve what you have done,

HighInt
;*** high priority interrupt code goes here ***  
		btfss	INTCON,INT0IF	;Check if it was INT0
		bra	Exit_int
		movlw	1
		xorwf	LATA,F
Exit_int	retfie	FAST

You could even remove the BRA as it's straight after it and make it,

;High priority interrupt vector

		ORG	0x0008
		btfss	INTCON,INT0IF	;Check if it was INT0
		bra	Exit_int
		movlw	1
		xorwf	LATA,F
Exit_int	retfie	FAST

Actually, as you only have one interrupt enabled there is no need to check which one and so,

;High priority interrupt vector

		ORG	0x0008
		movlw	1
		xorwf	LATA,F
		retfie	FAST

would suffice.

HTH

Mike.

 

[rnorman3]

THanks for the feedback!!

The XOR is a good point, I'm not familiar with all the asm instructions yet...thanks for the feedback!!

rn