sclk      bit       p3.2
       dat2      bit       p1.3
       key_num  equ        23h
       org      0000h
       ajmp     main
       org      0030h
  main:mov      p0,#0FFh
       clr      p2.1 
 main1:jnb      sclk,key     
       sjmp     main1
   key:acall    dill_key
       sjmp     main1          
dill_key:lcall  receive
         mov      a,key_num
         cjne     a,#0ffh,key2
         lcall    receive
         ret            
  key2:CJNE      A,#05H,JK4      ;F1
       CLR      p0.0
       ret
   JK4: CJNE      A,#06H,JK5      ;F2
        CLR      p0.1
       ret
   JK5: CJNE      A,#04H,JK6      ;F3
        CLR      p0.2
       ret
   JK6: CJNE      A,#0cH,JK7      ;F4
        CLR      p0.3
       ret
   JK7: CJNE      A,#03H,JK8      ;F5
        CLR      p0.4
       ret
   JK8: CJNE      A,#0bH,JK9      ;F6
        CLR      p0.5
       ret
   JK9: CJNE      A,#83H,JK10      ;F7
        CLR      p0.6
       ret
  JK10: CJNE      A,#0aH,JK11      ;F7
        CLR      p0.7
       ret     
   JK11:CJNE      A,#76H,key_ret      ;ESC
        mov       p0,#0FFh
        ret
   key_ret:ret

RECEIVE:CLR       A          ;接收數據子程序
        CLR       C
        MOV       R4,#08H
    IN4:JNB       SCLK,$     ;等待時鐘升高
        JB        SCLK,$     ;等到時鐘拉低
        MOV       C,DAT2
        RRC       A
        NOP
        DJNZ      R4,IN4     ;八位數據傳送完畢，繼續向下執行
        MOV       KEY_NUM,A
        JNB       SCLK,$
        JB        SCLK,$
        JNB       SCLK,$     ;這是最后一個時鐘信號
        JB        SCLK,$
        JNB       SCLK,$
        RET