I have a problem.

I am using a PIC16F877 and a timer triggered IRQ service routine.
Now, I have the problem, that sometimes, the main loop is hanging.
My suggestion is, that in certain condition, if the main loop is doing
some calculation, the IRQ is occuring, and something is not restored
after the IRQ was worked out. I know, that Push/Pull of registers must
be done by hand, but I am not sure, if I catched all I need.

My IRQ routine is as following:

	ORG     	0x004             ; interrupt vector location
	movwf   	w_temp            ; save off current W register
contents
	swapf		STATUS,W          ; move status register into W
register
	clrf    	STATUS      	; ensure file register bank set
to 0
	movwf		status_temp       ; save off contents of STATUS
register
	movf		PCLATH,W
	movwf		pclath_temp
	clrf		PCLATH
		
	call		ISR_H			; call the interrupt
service codes
		
	movf		pclath_temp,W
	movwf		PCLATH
	swapf		status_temp,w		
	movwf		STATUS           	; restore pre-isr STATUS
register contents
	swapf   	w_temp,f
	swapf   	w_temp,w         	; restore pre-isr W
register contents
	retfie                   	; return from interrupt


ISR_H
	...
	...
	...
	return


MAIN	
	...
	...
	...
	goto Main


Best Jens

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