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PICList Thread
'Help EEPROM'
1997\05\24@130113 by Francesco Cembrola

picon face
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
spam_OUTfcembrolaTakeThisOuTspamaol.com

1997\05\24@133055 by Tony Matthews

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face
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
> .....fcembrolaKILLspamspam@spam@aol.com
Display this reply full screen for proper formatting.
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.

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