Where to disable the GIE bit on a PIC interrupt? - Electronic Circuits Projects Diagrams Free

blueroomelectronics · 6th February 2007, 06:12 PM

Where in an Interrupt should you disable the GIE bit?
(or do you have to?)

Code:

         org      0x004             ;IRQ routines
Push     bcf      INTCON, GIE       ;Bx
         movwf    W_Stack             ;Bx given multiple banks, and no global memory 
         swapf    STATUS,W     ;Bx The swapf instruction, unlike the movf, affects NO status bits, which is why it is used here.
         clrf     STATUS             ;Bx point to bank 0 and clear all the flags

evandude · 6th February 2007, 07:08 PM

I don't use assembly very much, but I was under the impression it gets cleared automatically, otherwise it would get stuck in an infinite loop if you didn't immediately clear it.

looking at the datasheet for the 16F88 for example, it does say on the first page about interrupts that the GIE bit gets cleared, and that the instruction RETFIE automatically sets it again when exiting the ISR.

blueroomelectronics · 7th February 2007, 04:27 AM

You're right, it was from having to force GIE off from the old days.

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6th February 2007, 06:12 PM	(permalink)
blueroomelectronics	Where to disable the GIE bit on a PIC interrupt? Where in an Interrupt should you disable the GIE bit? (or do you have to?) Code: org 0x004 ;IRQ routines Push bcf INTCON, GIE ;Bx movwf W_Stack ;Bx given multiple banks, and no global memory swapf STATUS,W ;Bx The swapf instruction, unlike the movf, affects NO status bits, which is why it is used here. clrf STATUS ;Bx point to bank 0 and clear all the flags __________________ Bill Smart Kits build Smart People http://www.blueroomelectronics.com

6th February 2007, 07:08 PM	(permalink)
evandude	I don't use assembly very much, but I was under the impression it gets cleared automatically, otherwise it would get stuck in an infinite loop if you didn't immediately clear it. looking at the datasheet for the 16F88 for example, it does say on the first page about interrupts that the GIE bit gets cleared, and that the instruction RETFIE automatically sets it again when exiting the ISR. __________________ EEgeek.net

7th February 2007, 04:27 AM	(permalink)
blueroomelectronics	You're right, it was from having to force GIE off from the old days. __________________ Bill Smart Kits build Smart People http://www.blueroomelectronics.com