Francesco Cembrola wrote:
>
> Hello PIC'ers,
>
> I need some help. Despite my best efforts, I have not been able to write to
> the EEPROM of the PIC16C84. What I really would like is a written program of
> how this is done.
>
> Please could anyone show me how to do this? It is hard when you are a novice!
>
> Thank you all,
>
> Francesco Cembrola
> fcembrola@aol.com
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 Are you sure you are not writing? but maybe reading wrong?Do you
include eeprom data in your program listing? are you switching bank
bits  like you are supposed to ? Clip a relative piece of code for us to
look at.Are you writing sequential bytes or just one?

I read:
                BCF             STATUS,RPO              ; shift to bank zero
                MOVLW           D'5'                    ; register eeprom addres
s for ONES_BATCH
                MOVWF           EEADR                   ; load address of eedata
 needed
                BSF             STATUS,RPO              ; shift to bank one
                BSF             EECON,RD                ; eeread bit set
                BCF             STATUS,RPO              ; shift to bank zero
                MOVF            EEDATA,W                ; eedata in w register
                MOVWF           ONES_BATCH              ; preset the register fr
om eeprom value
I write :
                INCF            ONES_BATCH,F            ; increment the ones_bat
ch register
                BSF             STATUS,RPO              ; shift to bank one
                BSF             EECON,WREN              ; write enable bit
                BCF             STATUS,RPO              ; shift to bank zero
                MOVLW           D'5'                    ; address of BATCH eepro
m byte
                MOVWF           EEADR                   ; address register eepro
m
                MOVF            ONES_BATCH,W            ; load value of ONES_BAT
CH variable to EEPROM
                MOVWF           EEDATA                  ;
                BSF             STATUS,RPO              ; bank 1
                MOVLW           H'55'                   ; write 55h
                MOVWF           EECON2                  ; ""
                MOVLW           H'AA'                   ; write aah
                MOVWF           EECON2                  ; ""
                BSF             EECON,WR                ; set WR bit begin write
 CLEARED IN HDW
                BCF             EECON,WREN              ; DISABLE EEPROM WRITES
                BCF             STATUS,RPO              ; shift to bank zero
Some of this can no doubt be eliminated if the states on entry are known
but this as a call from anywhere routine works ok.