Post by thread:Internal EEPROM

Ive been reading through the docs for a 16F84 and I dont understand how to read and write a byte to the internal eeprom. There are 64 bytes on a f84. Im trying to do this in MPLAB to so i can visually see and learn the process, can anyone help me out? I would like to write a byte and read it back. Rob Send someone a cool Dynamitemail flashcard greeting!! And get rewarded. GO AHEAD! http://cards.dynamitemail.com/index.php3?rid=fc-41

Rob, Post what you did in source code so we can help you! Regards, S.- -----Original Message----- From: Rob R <spam_OUTelektrikmanTakeThisOuTDYNAMITEMAIL.COM> |Ive been reading through the docs for a 16F84 and I dont understand how to read and write a |byte to the internal eeprom. There are 64 bytes on a f84. Im trying to do this in MPLAB to |so i can visually see and learn the process, can anyone help me out? I would like to write a |byte and read it back. | |Rob

Hi Rob. It's very easy to read and write to the internal EEPROM in F/C84 here are some code examples: ;read eprom address, data will return in W, memory address must be ; set in EEADR, before call this sub. ; READEE CLRF EEDATA BSF STATUS,5 ;Goto BANK1 BSF EECON1,RD BCF STATUS,5 ;back BANK0 NOP ; only necessary if running at 10mhz. MOVF EEDATA,W RETURN ; ;Writing byte to internal EE : ;address byte must be in EEADR, and value in EEDATA ; WRITEE BSF STATUS,5 BSF EECON1,WREN MOVLW 0x55 MOVWF EECON2 MOVLW 0xAA MOVWF EECON2 BSF EECON1, WR BCF STATUS,5 MOVLW 1 CALL DELAY ;1 ms sub delay, to allow eeprom to write. RETURN I use this routines and works very good, If you ask me why to write 55h & AAh to EECON2 I have no idea, but this is the way that works ;-). Oh, I forgot! label definitions!: EEDATA equ 08 EEADR equ 09 EECON1 equ 88 EECON2 equ 89 WREN equ 2 RD equ 0 WR equ 1 I Hope it will be useful for you. see you. >Ive been reading through the docs for a 16F84 and I dont understand how to read >and write a byte to the internal eeprom. There are 64 bytes on a f84. Im >trying to do this in MPLAB to so i can visually see and learn the process, can >anyone help me out? I would like to write a byte and read it back. > >Rob > Leandro J. Laporta (LU2AOQ) mail: .....lu2aoqKILLspam@spam@yahoo.com wrk: Arg. Assoc. for Space Tech. ham: TCP/IP high speed group HSG __________________________________________________ Do You Yahoo!? Talk to your friends online with Yahoo! Messenger. http://im.yahoo.com

This is an easy one. Go to the microchip site and get their tech note about accessing eeprom. The secret is really a secret - they have some special instructions (that they won't tell us about) to move a byte from a special transfer point to and from any point in the eeprom. You just have to faithfully copy the 5 or 6 instructions from the tech note and it magically works. Bye. {Original Message removed}