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[SOLVED] problem with page write in eeprom 24c02

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pratzz

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Code: 
list p=PIC16F877a
#include <p16F877a.inc>
errorlevel -302
__config _HS_OSC & _WDT_OFF & _LVP_OFF
;-------------------------------------------
; SPECIAL FUNCTION REGISTERS
;-------------------------------------------
;*******************Macro definitions*****************************
WRITE_ADDR  equ     b'10100000' ; Control byte for write operations
READ_ADDR   equ     b'10100001' ; Control byte for read operations
rs  equ 0
rw equ 1
en equ 2
;*******************Include file**********************************

;-------------------------------------------
; GENERAL PURPOSE REGISTERS
;-------------------------------------------
		CBLOCK 20h
count 
count1
count3
count4
dat  
disp 
number
bytecount
temp
		ENDC


		ORG 0
		clrf STATUS
		movlw 00
		movwf PCLATH
		goto start
;-------------------------------------------
		org 04
		retfie
;----------------------------------------------
table
movlw HIGH $
movwf PCLATH
movf count1,w
addwf PCL,f
dt ' ',' ',' ',' ',' ','E','X','C','E','L',' ',' ',' ',' ',' ',' '
dt ' ',' ','T','E','C','H','N','O','L','O','G','I','E','S',' ',' '
;-----------------------------------------------------------------
table1
movlw HIGH $
movwf PCLATH
movf temp,w
addwf PCL,f
dt "     EEPROM     "
movlw 0c0h
call lcd_cmd
dt "  WRITE DONE   ",0
lcd_cmd
        movwf PORTD
        bcf PORTB,rs
        bcf PORTB,rw
        bsf PORTB,en
        call delay
        bcf PORTB,en
        retlw 00h
;------------------------------------------------------------------
lcd_data
        movwf PORTD
        bsf PORTB,rs
        bcf PORTB,rw
        bsf PORTB,en
        call delay
        bcf PORTB,en
        retlw 00h
;------------------------------------------------------------------
lcd_init
        movlw 38h
        call lcd_cmd
        call delay
        movlw 0eh
        call lcd_cmd
        call delay
        movlw 01h
        call lcd_cmd
        call delay
        movlw 06h
        call lcd_cmd
        call delay
        movlw 80h
        call lcd_cmd
        call delay
        call delay
         retlw 00h
;-------------------------------------------------------------------
delay
        movlw 02h
        movwf count3
here2   movlw 0ffh
        movwf count4
here    decfsz count4,1
        goto here
        decfsz count3,1
        goto here2
        retlw 00h
;-----------------------------------------------------------------


initialise
        clrf temp
        clrf count
        clrf count1
    	bcf STATUS,RP1
		bsf STATUS,RP0
        clrf TRISB
		clrf TRISD
		movlw b'00000111'
		movwf ADCON1
        movlw b'11111111'
        movwf   TRISC               ; Set PORTC to all inputs
        clrf    SSPSTAT             ; Disable SMBus inputs
        bsf     SSPSTAT,SMP         ; Disable slew rate control
        movlw   09h                ; Load 0x18 into WREG
        movwf   SSPADD              ; Setup 100 kHz I2C clock
        clrf    SSPCON2
		bcf     STATUS,RP0
        movlw   b'00101000'
        movwf   SSPCON              ; Enable SSP, select I2C Master mode
        bcf     PIR1,SSPIF          ; Clear SSP interrupt flag
        bcf     PIR2,BCLIF
		retlw 00
;--------------------------------------------------------------
genstart
   
    bcf     STATUS,RP1
    bcf     STATUS,RP0          ; Select Bank 00
    bcf     PIR1,SSPIF          ; Clear SSP interrupt flag
    bsf     STATUS,RP0          ; Select Bank 01
    bsf     SSPCON2,SEN         ; Generate Start condition
    bcf     STATUS,RP0          ; Select Bank 00
    start_wait
    btfss   PIR1,SSPIF          ; Check if operation completed
    goto    start_wait          ; If not, keep checking
    retlw   0
genstop
    bcf     STATUS,RP1
    bcf     STATUS,RP0          ; Select Bank 00
    bcf     PIR1,SSPIF          ; Clear SSP interrupt flag
    bsf     STATUS,RP0          ; Select Bank 01
    bsf     SSPCON2,PEN         ; Generate Stop condition
    bcf     STATUS,RP0          ; Select Bank 00
stop_wait
    btfss   PIR1,SSPIF          ; Check if operation completed
    goto    stop_wait          ; If not, keep checking
    retlw   00
genrepstart
    bcf     STATUS,RP1
    bcf     STATUS,RP0          ; Select Bank 00
    bcf     PIR1,SSPIF          ; Clear SSP interrupt flag
    bsf     STATUS,RP0          ; Select Bank 01
    bsf     SSPCON2,RSEN        ; Generate Restart condition
    bcf     STATUS,RP0          ; Select Bank 00
    repstart_wait
    btfss   PIR1,SSPIF          ; Check if operation completed
    goto    repstart_wait       ; If not, keep checking

    retlw   0
;-------------------------------------------------------------
--------------------------------------------
transmit
   
    bcf     STATUS,RP1
    bcf     STATUS,RP0          ; Select Bank 00
    bcf     PIR1,SSPIF          ; Clear SSP interrupt flag
    movf    dat,W           ; Copy dat to WREG
    movwf   SSPBUF              ; Write byte out to device
  tx_wait
    btfss   PIR1,SSPIF          ; Check if operation completed
    goto    tx_wait             ; If not, keep checking
    bcf     PIR1,SSPIF
  ; bsf     STATUS,RP0          ; Select Bank 01
 ;  btfsc   SSPCON2,ACKSTAT     ; Check if ACK bit was received
 ;  goto    ackfailed           ; This executes if no ACK received
    
    retlw   00h

;-----------------------------------------------------------
  
    pagewrite
    bcf     STATUS,RP1
    bcf     STATUS,RP0          ; Select Bank 00
    movlw   08h
    movwf   bytecount           ; Initialize counter to 16 bytes

    call    genstart              ; Generate start bit
                                ; Now we send the control byte
    bcf     STATUS,RP0          ; Select Bank 00
    movlw   WRITE_ADDR
    movwf   dat               ; Copy control byte to buffer
    call    transmit                 ; Output control byte to device

                                ; Send word address high byte
    bcf     STATUS,RP0          ; Select Bank 00
    movf    count,W                ; Use 0x5A for address to send
    movwf   dat               ; Copy address to buffer
    call    transmit


    bcf     STATUS,RP0          ; Select Bank 00
txbyte                          ; This loop transfers all 16 of
    call    table                            ; the data bytes to the device
    incf    count,1     ; Use bytecount as data value
    movwf   dat                      ; Copy data to buffer
    call    transmit                  ; Output data to device

    bcf     STATUS,RP0          ; Select Bank 00
    decfsz  bytecount,F         ; Check if finished looping
    goto    txbyte              ; Continue looping

    call    genstop               ; Generate stop bit
    ;call    Poll                ; Poll for write completion
    retlw   0
;-------------------------------------------
; Main program starts
;-------------------------------------------
start		call initialise
            call lcd_init
            
            call pagewrite
            call pagewrite
            call pagewrite
            call pagewrite
 y          call table1
            iorlw 00h
            btfsc STATUS,Z
            goto x
            call lcd_data
            incf temp,1
            goto y
 x           goto x

   end
only my first and last page call are wrking and corresponding data is getting written into it.
 

I am using pic18f458 to write data to eeprom 24c02 & am correctly writing and reading data upto 256 bytes (upto page 1) , once i write data after 256 bytes its overwriting from begining .plz help how to write data to eepom after 256bytes memory location.
 
Last edited:

to my knowledge 24c02 has capacity of 256 bytes only i.e. 256*8 bits = 2k
 

pratzz said:
to my knowledge 24c02 has capacity of 256 bytes only i.e. 256*8 bits = 2k
Click to expand...

thank u..it has 32 pages of 8 bytes each(32*8=256bytes)...but its memory is 2K & i am sure i used only 256 bytes then how to access remaining memory.

( AT24C02, 2K SERIAL EEPROM: Internally organized with 32 pages of 8 bytes each,
the 2K requires an 8-bit data word address for random word addressing......from datasheet)
 

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