;交通燈模擬實驗程序
      GEWEI EQU 21H     ;個位數據
      SHIWEI EQU 23H    ;十位數據
      SCANLED EQU 25H
      SCANMODE EQU 26H
      RED EQU 28H
      GREEN EQU 29H
      YELLOW EQU 32H
      NUMTIM EQU 33H
      LED EQU  34H


      ORG 000H
      JMP START
      ORG 0BH
      JMP TIMER0
      ORG 100H
START:MOV SP,#50H
      MOV R0,#20H
      MOV R5,#20
 CLR0:MOV @R0,#00H
      INC R0
      DJNZ R5,CLR0
      MOV TMOD,#01H       ;設置定時器
      MOV TH0,#HIGH(65536-5000)
      MOV TL0,#LOW(65536-5000)
      SETB TR0
      MOV IE,#10000010B
      MOV P0,#0FFH
      MOV P1,#0FFH
      MOV P2,#00H
      MOV P3,#0FFH
      MOV R3,#10
      MOV R2,#3
      MOV R1,#10
      MOV R7,#200
      MOV RED,#10
      MOV YELLOW,#3
      MOV GREEN,#10
      MOV NUMTIM,#10
      MOV LED,#0FFH
      AJMP $


      ;=======================

  TIMER0:PUSH ACC
         PUSH PSW
         MOV TH0,#HIGH(65536-5000)
         MOV TL0,#LOW(65536-5000)
         DJNZ R7,RET0
         MOV R7,#200
          MOV   A,SCANMODE
          MOV   B,#4
          DIV   AB
          MOV   A,B
          RL    A
          MOV   DPTR,#TAB_SCAN
          JMP   @A+DPTR
TAB_SCAN: AJMP  RED_LIGHT
          AJMP  YEL_LIGHT
          AJMP  GRE_LIGHT
          AJMP  YEL_LIGHT
   RET0:  MOV  A,NUMTIM
          LCALL BIN_BCD
          MOV SHIWEI,A
          MOV GEWEI,B
          INC   SCANLED
          MOV   A,SCANLED
          MOV   B,#4
          DIV   AB
          MOV   A,B
          RL    A
          MOV   DPTR,#TAB_SCAN0
          JMP   @A+DPTR
TAB_SCAN0:AJMP  SCAN_L1
          AJMP  SCAN_L2
SCAN_L1: MOV   P2,#11111011B
         MOV   A,SHIWEI
         JMP   END_SCAN
SCAN_L2: MOV   P2,#11110111B
         MOV   A,GEWEI
         JMP   END_SCAN
END_SCAN:MOV   DPTR,#TABLE
         MOVC  A,@A+DPTR
         MOV   P0,A
         MOV   A,LED
         MOV   P1,A
         POP PSW
         POP ACC
         RETI

RED_LIGHT:MOV  LED,#11111100B
          MOV  NUMTIM,RED
          DEC  RED
          MOV  A,RED
          CJNE A,#0FFH,RET0
          MOV  RED,#10
          MOV  A,SCANMODE
          ADD  A,#01H
          MOV  SCANMODE,A
          JMP  RET0
YEL_LIGHT:MOV  LED,#11110011B
          MOV  NUMTIM,YELLOW
          DEC  YELLOW
          MOV  A,YELLOW
          CJNE A,#0FFH,RET0
          MOV  YELLOW,#3
          MOV  A,SCANMODE
          ADD  A,#01H
          MOV  SCANMODE,A
          JMP  RET0
GRE_LIGHT:MOV  LED,#11001111B
          MOV  NUMTIM,GREEN
          DEC  GREEN
          MOV  A,GREEN
          CJNE A,#0FFH,RET1
          MOV  GREEN,#10
          MOV  A,SCANMODE
          ADD  A,#01H
          MOV  SCANMODE,A
     RET1:JMP  RET0



 BIN_BCD:MOV  B,#10
         DIV  AB
         RET

 DELAY: MOV   R5,#02
    D1: MOV   R6,#200
    D2: MOV   R7,#200
        DJNZ  R7,$
        DJNZ  R6,D2
        DJNZ  R5,D1
        RET

TABLE:DB  0C0H,0F9H,0A4H,0B0H,99H,92H,82H,0F8H,80H,90H    ;共陽字碼表
END