Paul Duffy wrote:
> void write(char data, char address)     //writes 8 bit data to address in eeprom
>  {
>  eedata = data;
>  eeadr = address;
>  eecon1 = 0b00000100;
>  eecon2 = 0x55;
>  eecon2 = 0xAA;
>  eecon1 = 0b00000110;
>  while(test_bit(eecon1,1));                 //wait for write to complete
>  eecon1 = 0;
>  pir1 =0;                                          //clear interrupt flages - PIR1<7>
>  }

Try writing the write() routine in assembler, or at least the write 
sequence (55,AA,WR). Note that the datasheet specifies that the exact 
sequence shown must be used, and you don't know how the C compiler might 
do it.

Here's the EEPROM write protocol, in assembler:

	BSF   EECON1,WREN ;Enable writes
	BCF   INTCON,GIE  ;Disable INTs.

	; BEGIN REQUIRED EXACT SEQUENCE
	MOVLW 55h         ;
	MOVWF EECON2      ;Write 55h
	MOVLW AAh         ;
	MOVWF EECON2      ;Write AAh
	BSF   EECON1,WR   ;Set WR bit to
                   	;begin write
	; END REQUIRED EXACT SEQUENCE
	
	BSF   INTCON,GIE  ;Enable INTs.
	BCF   EECON1,WREN ;Disable writes



-- 
Hector Martin (hector@marcansoft.com)
Public Key: http://www.marcansoft.com/marcan.asc

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