I do have an ISR in my real code.  I posted a simplified version of the code.  I also do have an end less loop at the end.  Removing GIE and adding endless loop doesn't solve my problem.



----- Original Message ----
From: Tamas Rudnai <tamas.rudnai@gmail.com>
To: Microcontroller discussion list - Public. <piclist@mit.edu>
Sent: Monday, November 3, 2008 9:55:32 PM
Subject: Re: [PIC] EEPROM won't change

Why are you tickling the GIE if you do not have ISR, anyway? Also you do not
have a never ending loop at the end of your code so the execution will
continue through the uninitialised program memory until the PC overflows and
your firmware starts up againg... and again... and again...

Tamas


On Mon, Nov 3, 2008 at 3:07 PM, alan smith <micro_eng2@yahoo.com> wrote:

> You either need to use the interupt to determine when the write is
> complete, or add a delay to ensure the write completes.  Refer to the data
> sheet where it details exactly how the write sequence occurs.
>
>
> --- On Mon, 11/3/08, Hasan Khan <hasan@khansden.com> wrote:
>
> > From: Hasan Khan <hasan@khansden.com>
> > Subject: [PIC] EEPROM won't change
> > To: "PIC List" <piclist@mit.edu>
> > Date: Monday, November 3, 2008, 6:35 AM
> > Hi,
> > I have a project where I need to write some constant values
> > into eeprom of a 16f84a.  I am writing the code in mplab and
> > testing it on its simulator.  This code won't work
> > because simulator shows no change in eeprom values or the
> > registers EECON1 and EECON2.  It does show EEDATA and EEADR
> > changin.  Here is the simplified code.  Thanks for any help.
> >
> > #include p16f84a.inc
> >
> > list p=16f84a
> >
> >   org        0x00
> >
> >   ;initialize EEPROM
> >   banksel    EEDATA
> >   movlw        0x34
> >   movwf        EEDATA
> >   movlw        0x01
> >   movwf        EEADR
> >
> >   bsf        STATUS, RP0        ; BANK 1
> >   bcf        INTCON, GIE
> >
> >   bsf         EECON1, WREN     ; Enable Write
> >   movlw     0x55
> >   movwf     EECON2             ; Write 55h
> >   movlw     0xAA
> >   movwf     EECON2             ; Write AAh
> >   bsf         EECON1,WR         ;  Set WR bit
> >
> >   bsf        INTCON, GIE
> >   bcf        STATUS,RP0        ; BANK 0
> >
> >   end
> >
> >
> > --
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>
>
>
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