Discussion in "Project Help" started by    navintiwari08    Apr 12, 2012.
Thu Apr 12 2012, 07:10 PM
#1
hello everyone..
am having problem in writing and reading data from serial eeprom 24c02 interfaced with 8051(P89V51RD2).. please have a look at my program and help me out..
thanks a bunch:)

;-------------------------------------------
; using atmel 24c02 serial eeprom with 8051
;-------------------------------------------
sda equ p2.0
scl equ p2.1

org 00h
sjmp main

org 30h
main:

lcall eeprom_write
lcall eeprom_read
here:
sjmp here


eeprom_start:
setb sda
setb scl
lcall delay
clr sda
lcall delay
clr scl
ret

eeprom_stop:
clr sda
setb scl
lcall delay
setb sda
lcall delay
clr scl
ret

eeprom_write:
lcall eeprom_start
mov a,#0a0h ;device address with write bit
lcall send_data
mov a,#00h ;memory address on device to write to
lcall send_data
mov a,#25h ;data to write on the eeprom
lcall send_data
lcall eeprom_stop
ret

eeprom_read:
lcall eeprom_start
mov a,#0a0h ;device address with write bit(to perform dummy write)
lcall send_data
mov a,#00h ;memory address on device to set the address pointer
lcall send_data
lcall eeprom_start ;repeated start
mov a,#0a1h ;device address with read bit
lcall send_data
lcall get_data ;start reading
lcall eeprom_stop
ret

send_data:
mov r0,#08
loop: clr scl
lcall delay
rlc a
mov sda,c
lcall delay
setb scl
lcall delay
clr scl
djnz r0,loop
setb sda
ack: jb sda,ack ;polling the acknowledge by the device
setb scl
lcall delay
clr scl
ret

get_data:
mov r0,#08
setb sda
nop
loop1:
mov c,sda
setb scl
nop
nop
clr scl
rlc a
djnz r0,loop1
mov p0,a
ret

delay: mov r1,#10
rep: djnz r1,rep
ret

end


[ Edited Thu Apr 12 2012, 07:18 PM ]
Sat Apr 14 2012, 03:01 AM
#2
you have to put delay of atleast 5 to 10 ms after eeprom write to complete the write cycle. I am assuming your I2C is working fine.
Sat Apr 14 2012, 08:28 AM
#3
hello Ajay.. thanx for the reply.. i tried giving it the delay u proposed but it is still not working.. is my program correct? i checked many times but cant spot the error.. pls help. thanks..
Sun Apr 15 2012, 04:43 AM
#4
I dont see any problem the way you are reading from EEPROM but as I said, I am assuming your I2C driver is correct and working fine. You can take i2c reference from tutorial section. and see if everything is alright.
Sun Apr 15 2012, 08:23 AM
#5
thanks a lot Ajay, for the help.. i just solved it.. the 24c02a IC was damaged. i think i burnt it up.. i got a new 24c02 and its working perfectly.. thanks for caring to reply.. have a great day:)
Mon Apr 16 2012, 06:21 PM
#6
thats a good news. keep up the good work. Good Luck!

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