On Sat, Sep 12, 2009 at 7:50 PM, Wouter van Ooijen <wouter@voti.nl> wrote:
>> from the datasheet, all that i do find to handle an interrupt:
>>
>> isr
>> clear INT_FLAG
>> retfie
>>
>>
>> that's all what i do need. Or do i miss something ?
>
> save and restore everything you are messing with. W, status, maybe
> PCLATH, etc.


Changed the code to Save and Restore during an interrupt, but that
doesn't cause any change at all..


	PROCESSOR	16f72
	#include "p16f72.inc"
	
	__CONFIG _CP_OFF & _WDT_OFF & _PWRTE_ON & _HS_OSC

loopus_a	EQU 0x2d

loopms_a	EQU 0x2e
loopms_b	EQU 0x2f
loopms_c	EQU 0x30

flags		EQU 0x31
w_tmp		EQU 0x32
status_tmp	EQU 0x33
pclath_tmp	EQU 0x34
fsr_tmp		EQU 0x35


LEDPORT	equ	PORTA
LEDBIT	equ	1

	org	0x0
	goto	init

	org	0x4
	goto	isr

	#include "delays.inc"

init
	clrf	flags

	banksel	TRISA
	movlw	0x06
	movwf	ADCON1
	movlw	0x00			; Port A output
	movwf	TRISA

	movlw	0x01			; RB.0 int
	movwf	TRISB

	banksel	OPTION_REG
	bcf	OPTION_REG, INTEDG	; falling edge int
	bsf	OPTION_REG, NOT_RBPU	; disable pullup
	bsf	INTCON, INTE		; enable RB.0 int
	bsf	INTCON, GIE		; global int

	banksel	LEDPORT

main
	btfsc	flags, LEDBIT
	bsf	LEDPORT, LEDBIT		; LED on
	movlw	0xff
	call	delay_ms

	bcf	LEDPORT, LEDBIT		; LED off
	movlw	0xff
	call	delay_ms

	clrf	flags			; clear all flags
	goto	main

isr
; save registers
	movwf	w_tmp			; save w
	swapf	STATUS, w		; swap status
	clrf	STATUS			; bank0
	movwf	status_tmp		; save status
	movf	PCLATH, w		; save pclath
	movwf	pclath_tmp
	clrf	PCLATH
	movf	FSR, w			; save fsr
	movwf	fsr_tmp

; actual ISR
	bcf	INTCON, INTF
	bsf	flags, LEDBIT

; restore registers
	movf	fsr_tmp, w
	movwf	FSR
	movf	pclath_tmp, w
	movwf	PCLATH
	swapf	status_tmp, w		; set bank to original
	movwf	STATUS			; restore
	swapf	w_tmp, f		; swap tmp
	swapf	w_tmp, w		; swap tmp -> w

	retfie

	END
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