SDA24  EQU P3.7 
SCLK24 EQU P3.6 
ORG 0000
AJMP    MAIN
ORG 0030H
MAIN:

mov a,#55h
mov b,a
mov a,#00h
lcall wt24
mov a,#00h
lcall rd24
mov p0,a
ajmp $


RD24:  PUSH ACC     ;讀24C02子程序。
        SETB SDA24
        CLR SCLK24
        CALL START24    ;啟動
        MOV A,#0A0H
        CALL SHIFT8     ;移位
        CALL ACK    ;響應
        POP ACC
        CALL SHIFT8
        CALL ACK
        CALL START24
        MOV A,#0A1H
        CALL SHIFT8
        CALL ACK
        SETB SDA24
        MOV R7,#8
        CLR A
        SETB SDA24
RD000:  RL A        ;8個位
        SETB SCLK24
        MOV C,SDA24
        MOV ACC.0,C
        CLR SCLK24
        DJNZ R7,RD000
        RET
;-------------------------------
;寫入24C02程序：
WT24:   PUSH ACC
        SETB SDA24
        CLR SCLK24
        CALL START24
        MOV A,#0A0H
        CALL SHIFT8
        CALL ACK
        POP ACC
        CALL SHIFT8
        CALL ACK
        MOV A,B
        CALL SHIFT8
        CALL ACK
        CALL STOP
        CALL DELAY2
        RET
; -------------------------------
;開始條件
START24:CLR SDA24
        SETB SDA24
        SETB SCLK24
        CLR SDA24
        CLR SCLK24
        RET

;停止條件
STOP:   CLR SDA24
        SETB SCLK24
        SETB SDA24
        RET

;應答信號
ACK:    SETB SCLK24
        CLR SCLK24
        RET

;讀、寫數據
SHIFT8: MOV R7,#8
SH01:   RLC A
        MOV SDA24,C
        SETB SCLK24
        CLR SCLK24
        DJNZ R7,SH01
        RET

DELAY2:         ;延時
    NOP
    NOP
    NOP
    NOP
    RET

END