有时能写上并正确,有时出错1个字.有时只写上00地址的一个.请帮忙分析什么原因,硬件没有问题.
PADDR EQU 0 ; programmable address (0..7)
SIZE EQU 100h ; bytes per AT24C02
PSIZE EQU 8 ; bytes per page for AT24C02
FILL EQU 55h ; example fill value
SCL BIT P3.4
SDA BIT P3.5
setb SDA
setb SCL
mov r1,#FILL
mov r2,#0
mov r3,#100
mov r4,#4
x52:mov a,#PADDR
call writebyte
jnc x53
djnz r4,x52
setb c
jmp x54
x53:
inc r2
djnz r3,x52
clr c
x54:
ret
writebyte:
call start
jc x49
rl a
orl a,#FADDR
clr acc.0
call shout
jc x48
; mov a,r3
; call shout
; jc x48
mov a,r2
call shout
jc x48
mov a,r1
call shout
jc x48
clr c
x48:
call stop
x49:
ret
start:
;发送开始信号,在SCL为1时，SDA从1跳到0
;SDA,SCL返回0
;总线无效CY设置为1
setb SDA
setb SCL
jnb SDA,X40
jnb SCL,X40
nop
clr SDA
nop
nop
nop
nop
nop
CLR SCL
CLR C
jmp X41
X40:setb C
X41:ret
stop:
;发送停止信号，SCL为1时，SDA从0跳到1
;SCL,SDA返回1
clr SDA
nop
nop
setb SCL
nop
nop
nop
nop
nop
setb SDA
ret
shout:
;发送1个字节到at24cxx.
mov r0,#8
X42:rlc a
mov SDA,C
nop
nop
setb SCL
nop
nop
nop
nop
clr SCL
djnz r0,X42
setb SDA
nop
nop
setb SCL
nop
nop
nop
nop
mov c,SDA
clr SCL
ret
end |
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