Need help on code debug, many thanks

[choi_new]

Dear Friend,

Sorry, is me again.
I have writen a 8051 code to access AT24C512 data.
BTW, I found my program only can read FFH from the EPROM when I using EMU board, but I already burned a bmp file into the EEPROM.

Hence, I think my program have bug.

The below is my code.
can someone help me to find out the program??

Thanks a million!!!!


Peter
;;==== code


SDA BIT P2.2
SCL BIT P2.3
;SDA BIT P2.3
;SCL BIT P2.2

ADD0 BIT P2.0
ADD1 BIT P2.1

FADDR EQU 0A0H

ADDR_HI1 EQU 30H
ADDR_LO1 EQU 31H
ADDR_HI2 EQU 32H
ADDR_LO2 EQU 33H
RAM_DATA EQU 34H
ORG 00H

MOV ADDR_HI1, #00H
MOV ADDR_LO1, #00H
MOV ADDR_HI2, #00H
MOV ADDR_LO2, #00H
MOV RAM_DATA, #00H

I2C:
INC DPTR
MOV ADDR_HI2, DPH
MOV ADDR_LO2, DPL

LCALL READ_RANDOM
NOP
MOV A, RAM_DATA
MOV A, RAM_DATA
MOV A, RAM_DATA
MOV A, RAM_DATA
SJMP I2C
READ_CURRENT:
; AT24Cxx Current Address Read function.
; Called with programmable address in A. Returns data in A.
; Returns CY set to indicate that the bus is not available
; or that the addressed device failed to acknowledge.

LCALL START
JC X_45 ; abort if bus not available
; RL A ; programmable address to bits 3:1
; ORL A, #FADDR ; add fixed address
; SETB ACC.0 ; specify read operation

MOV A, #0A0H
LCALL SHOUT ; send device address
JC X_44 ; abort if no acknowledge

LCALL SHIN ; receive data byte
MOV RAM_DATA, A
LCALL NAK ; do not acknowledge byte
CLR C ; clear error flag
X_44:
LCALL STOP
RET
X_45:
RET


READ_RANDOM:
; AT24Cxx Random Read function.
; Called with programmable address in A, byte address in
; register pair ADDR_HI:ADDR_LO. Returns data in A.
; Returns CY set to indicate that the bus is not available
; or that the addressed device failed to acknowledge.
PUSH B
MOV B, A ; save copy of programmable address

; Send dummy write command to set internal address.

LCALL START
JC X_47 ; abort if bus not available
; RL A ; programmable address to bits 3:1
; ORL A, #FADDR ; add fixed address

; CLR ACC.0 ; specify write operation
MOV A, #0A0H
LCALL SHOUT ; send device address
JC X_46 ; abort if no acknowledge

MOV A, ADDR_HI1 ;; send high byte of address
LCALL SHOUT ;
JC X_46 ; abort if no acknowledge

MOV A, ADDR_LO1 ; send low byte of address
LCALL SHOUT ;
JC X_46 ; abort if no acknowledge

MOV A, ADDR_HI2 ;; send high byte of address
LCALL SHOUT ;
JC X_46 ; abort if no acknowledge

MOV A, ADDR_LO2 ; send low byte of address
LCALL SHOUT ;
JC X_46 ; abort if no acknowledge
; Call Current Address Read function.
MOV A, B ; get programmable address
LCALL READ_CURRENT

LJMP X_47 ; exit
X_46:
LCALL STOP


X_47: POP B
RET


START:
; Send START, defined as high-to-low SDA with SCL high.
; Return with SCL, SDA low.
; Returns CY set if bus is not available.

SETB SDA
SETB SCL

; Verify bus available.
JNB SDA, X_40 ; jump if not high
JNB SCL, X_40 ; jump if not high
NOP ; enforce setup delay and cycle delay
CLR SDA
nop ; enforce hold delay
nop ;
nop ;
nop ;
nop ;
CLR SCL

CLR C ; clear error flag
SJMP X_41
X_40:
SETB C ; set error flag
X_41:
RET

STOP:
; Send STOP, defined as low-to-high SDA with SCL high.
; SCL expected low on entry. Return with SCL, SDA high.
CLR SDA
nop ; enforce SCL low and data setup
nop
SETB SCL
nop ; enforce setup delay
nop ;
nop ;
nop ;
nop ;
SETB SDA
RET


SHOUT:
; Shift out a byte to the AT24Cxx, most significant bit first.
; SCL, SDA expected low on entry. Return with SCL low.
; Called with data to send in A.
; Returns CY set to indicate failure by slave to acknowledge.
; Destroys A.
PUSH B
MOV B, #8 ; bit counter
X_42:
RLC A ; move bit into CY
MOV SDA, C ; output bit
nop ; enforce SCL low and data setup
SETB SCL ; raise clock
nop ; enforce SCL high
nop ;
nop ;
nop ;
CLR SCL ; drop clock
DJNZ B, X_42 ; next bit

SETB SDA ; release SDA for ACK
nop ; enforce SCL low and tAA
nop ;
SETB SCL ; raise ACK clock
nop ; enforce SCL high
nop ;
nop ;
nop ;
MOV C, SDA ; get ACK bit
CLR SCL ; drop ACK clock
;LCALL ACK
POP B
RET

SHIN:
; Shift in a byte from the AT24Cxx, most significant bit first.
; SCL expected low on entry. Return with SCL low.
; Returns received data byte in A.
; SETB SDA ; make SDA an input
; PUSH B
; MOV B, #8 ; bit count
;X_43:
; nop ; enforce SCL low and data setup
; nop ;
; nop ;
; SETB SCL ; raise clock
; nop ; enforce SCL high
; nop ;
; MOV C, SDA ; input bit
; RLC A ; move bit into byte
; CLR SCL ; drop clock
; DJNZ B, X_43 ; next bit
; POP B
; RET
SETB SDA ;； make SDA an input，使SDA为高，准备读
PUSH B ;
MOV B, #08D ;;;;； bit count，设置位计数器
L2: NOP ;； enforce SCL low and data setup，保持SCL为低且使数据稳定
NOP
SETB SCL ;； raise clock，升高时钟
NOP ;； enforce SCL high，保持SCL为高
NOP
MOV C, SDA ;； input bit，输入位
RLC A ;； move bit into byte，将位移入A
CLR SCL ;； drop clock，降低时钟

DJNZ B, L2 ;； next bit，传送下一位
POP B
RET




NAK:
; Clock out a negative acknowledge bit (high).
; SCL expected low on entry. Return with SCL low, SDA high.

SETB SDA ; NAK bit
nop ; enforce SCL low and data setup
nop ;
SETB SCL ; raise clock
nop ; enforce SCL high
nop ;
nop ;
nop ;
CLR SCL ; drop clock
RET

ACK:

; Clock out an acknowledge bit (low).
; SCL expected low on entry. Return with SCL, SDA low.

clr SDA ; ACK bit
nop ; enforce SCL low and data setup
nop ;
setb SCL ; raise clock
nop ; enforce SCL high
nop ;
nop ;

Added after 1 minutes:

just a remind, I am not the aurthor of this code.
I just change the code for my application after I read it.

So, I am not copy right holder

 

[choi_new]

is that possible the incorrect time delay cause the problem??

 

[hamed_sotoudi]

first try to check your hardware.your connections and eeprom pins.(data busses ond others).then if there isnt any problem check your timing maybe your eepron cant reply to micro in the time period that you adjust for it.and try to read a very simple data from it(test your eeprom with 5555... and then with AAAA... in it).

 

[choi_new]

Dear friend,

I have fixed the problem!!
Thanks a millions for your advise

Best Regards,

Peter