Writing Data to the EEPROM - Electronic Circuits Projects Diagrams Free

Electrix · 26th August 2005, 01:26 PM

Need some help guys.

How do I write my data to the EEPROM. For eg: In a PIC 16F84 during processing I want to transfer data into the EEPROM. Can someone please send me a short code(in assembly :wink: ) to do a simple EEPROM transfer.
Another thing, how are the EEPROM address computed. I mean they start from 2000H or something ,how ??

**Nigel Goodwin** · 26th August 2005, 01:29 PM

It's all explained in the datasheet!.

You access the internal EEPROM through special data registers, basically one for the address (0-63 in your case) and one for the data. But it's all explained in the datasheet, including the special methods required to write to it.

If you check my tutorials, the IR one shows how to read and write the EEPROM (for storing and restoring the last remote control operation).

ym2k · 31st August 2005, 06:39 AM

Quote:

Originally Posted by Electrix

Need some help guys.

How do I write my data to the EEPROM. For eg: In a PIC 16F84 during processing I want to transfer data into the EEPROM. Can someone please send me a short code(in assembly :wink: ) to do a simple EEPROM transfer.
Another thing, how are the EEPROM address computed. I mean they start from 2000H or something ,how ??

Ok, here is how u do it.
First set your eeprom address.

Code:

;EEprom data address
;===================
EEMCNT1		equ	h'00'

then to do a read from the eeprom address,

Code:

;eeprom read
;-----------
eemodrd	bsf     status,rp0      ;Change to Bank1

	movlw	EEMCNT1		
	movwf	eeadr		;copy to eedata
	bsf	eecon1,rd	;read data from eeprom address
	movf	eedata,w	
	bcf     status,rp0      ;Change to Bank0
	movwf	mCnt1	;this is where you move the retrive eeprom data to other address

To write to an eeprom,

Code:

;eeprom write
;------------
eemodwr	movf	mCnt1,w ;this is where the data you wish to write to eeprom	
	bsf     status,rp0      ;Change to Bank1 
	bsf	eecon1,wren	;enable eeprom write

	movwf	eedata		;copy to eedata
	movlw	EEMCNT1		
	movwf	eeadr		;copy to eeadr
	movlw	h'55'
	movwf	eecon2
	movlw	h'aa'
	movwf	eecon2
	bsf	eecon1,wr	;write data to eeprom
	btfsc	eecon1,wr	;loop till write process is finish
	goto	$-1
	bcf     status,rp0      ;Change to Bank0

Once you declare the eeprom address to a variable, you can easily write and read from it. The code i provide will do general read & write function for eeprom. You just need to replace "mCnt1" to your own desire variable for reading and writing. You can leave the rest of the code and it should work. If you still in doubt, feel free to ask more

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26th August 2005, 01:26 PM	(permalink)
Electrix	Writing Data to the EEPROM Need some help guys. How do I write my data to the EEPROM. For eg: In a PIC 16F84 during processing I want to transfer data into the EEPROM. Can someone please send me a short code(in assembly :wink: ) to do a simple EEPROM transfer. Another thing, how are the EEPROM address computed. I mean they start from 2000H or something ,how ??

26th August 2005, 01:29 PM	(permalink)
Nigel Goodwin	It's all explained in the datasheet!. You access the internal EEPROM through special data registers, basically one for the address (0-63 in your case) and one for the data. But it's all explained in the datasheet, including the special methods required to write to it. If you check my tutorials, the IR one shows how to read and write the EEPROM (for storing and restoring the last remote control operation). __________________ PIC programmer software, and PIC Tutorials at: http://www.winpicprog.co.uk