Hi!
I am a Hong Kong student. This is my first time to write 8051 code and post topic here(My english is not very good,please don't blame me...)
I am doing a project on 8051(89c55)which need to interface a serial flash(AT45DB041B).
I had read all material (AT45DB041B datasheet,and something about SPI).
I follow the procedure which is written in the datasheet. But I am still not able to solve the problem.I cant write anything in the flash...

Here is my code

org 0000h

si equ p1.1
sck equ p1.2
cs equ p1.3
so equ p1.4
wp equ p1.5

clr si
clr so
clr sck

start:
setb wp
clr cs ;enable the flash
mov r0,#46H ;the data i want to write in the flash
;================================
mov r5,#78D ;time delay to allow the flash warm up
l2:
mov r7,#00H
l1:
nop
djnz r7, l1
djnz r5, l2

;=======write process============

acall c_write
acall command ;clock the 8 bits into the flash
acall rev_addr
acall command
mov a,#00h ;choose page 0
acall command
mov a,#00h ;start from 00 in page 0
acall command
mov a,r0
acall command
setb cs ;terminate the operation


nop
;=======read process===============

clr cs
acall c_read
acall command
acall rev_addr
acall command
mov a,#00h ;choose page 0
acall command
mov a,#00h ;start from 00 in page 0
acall command
acall dont_care ;32 dont care bits,whcih is needed for read command
acall recieve ;to recieve the 8 bit and store in a
setb cs
mov r1,a ;store the final result in r1


jmp start

c_read: ;read the main memory directly
mov a,#0D2H ;opcode
ret

c_write: ;write main memory page through buffer
mov a,#82h
ret

rev_addr: ;4 reserved bit and 4 bit addr,i make it all 0
mov a,#00h
ret

command: ;input the command to the flash
mov r6,#8
again:
rlc a
mov si,c ;send the bit
setb sck ;give a sck to memory to recieve signal
clr sck
djnz r6,again
ret

recieve: ;recieve the data
mov r6,#8
again1:
setb sck
clr sck ;give a sck to memory to recieve signal
mov c, so
rlc a
djnz r6,again1
ret

dont_care:
mov a,#00h
mov r6,#32
again2:
rlc a
mov si,c
setb sck
clr sck
djnz r6,again2
ret

end

I think the problem may be due to the clock input to the flash.But i still dont know which part is going wrong.
I had try many methods but it is still not work.I know the problem i asked is little bit long and confusing.Since i respond this part of the project,i really want to finish it...
If anyone have any comments, please feel free to say.
I deeply appreciate that!