org 0000h
main:
        mov p1,#0ffh
        lcall start
        mov a,#40h
        lcall sendbyte
        mov a,#0c0h
        lcall sendbyte
        lcall del
        lcall del
        mov a,#0f9h
        lcall sendbyte
        lcall del
        lcall del
        mov a,#0a4h
        lcall sendbyte
        lcall del
        lcall del
        lcall stop
        ljmp main


start:
        setb p1.0        ;sda
        setb p1.1        ;scl
        clr p1.0
        lcall delay
        clr p1.1
        ret

delay:
         nop
         ret

stop:      
         clr p1.0                ;sda
         setb p1.1               ;scl
         setb p1.0
         ret

sendbyte:
         mov r6,#08h             ;set counter for 8 bits
loop:
         jnb acc.7,notone
         setb p1.0     
         sjmp one
notone:  
         clr p1.0
one:
         setb p1.1               ; TRANSITION SCL LOW-TO-HIGH
         rl a                    ; ROTATE ACC LEFT 1-BIT
         clr p1.1                ; TRANSITION SCL LOW-TO-HIGH
         djnz r6,loop            ; LOOP FOR 8-BITS
         setb p1.0               ; SET SDA HIGH TO LOOK FOR
         setb p1.1               ; ACKNOWLEDGE PULSE
         jnb p1.0,sb             ; CHECK FOR ACK OR NOT ACK

                                 ; NOT ACK
sb:
         lcall delay             ; DELAY FOR AN OPERATION
         clr p1.1                ; TRANSITION SCL HIGH-TO-LOW
         lcall delay             ; DELAY FOR AN OPERATION
         ret

del:
         mov r0,#45h
l3:      mov r1,#50h
l2:      mov r2,#60h
l1:      djnz r2,l1
         djnz r1,l2
         djnz r0,l3
         ret
end