This is on a 16F processor...not sure what your using, but its pretty much the same on 18F if I recall.  This works..was using it all weekend long


EEPROM_WRITE:

	movf	EEPROM_ADR,w	; load with value in w
	banksel	EEADR
	movwf	EEADR
	clrf	EEADRH
	banksel	0
	movf	EEprom_Data,w
	banksel	EEDATA
	movwf	EEDATA

	banksel	EECON1
	bcf	EECON1,EEPGD
	bsf	EECON1, WREN
 
         movlw   H'55'           ; magic sequence
         movwf   EECON2               
         movlw   H'AA'                  
         movwf   EECON2    
      
         bsf     EECON1,WR  
  	bsf     EECON1,WREN            
         bcf     EECON1,EEIF     ; clear the interrupt flag
_wloop
	btfsc	EECON1,EEIF
	goto	_wloop

	banksel	EECON1
  	bcf 	EECON1, WREN 	; disable EEPROM write
	banksel	0
	return 


--- On Mon, 11/3/08, Hasan Khan <hasan@khansden.com> wrote:

> From: Hasan Khan <hasan@khansden.com>
> Subject: Re: [PIC] EEPROM won't change
> To: "Microcontroller discussion list - Public." <piclist@mit.edu>
> Date: Monday, November 3, 2008, 9:45 AM
> 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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> archive
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