一、設計任務
1、單片機的P0口接在7SEG-MPX8上，P2.0~P2.3口接74LS138的A 、B、C口，Y0~Y7接在數碼管位選的1~8上。用單片實現：數字1~8從數碼管的最右邊依次向左邊移動，就像拉幕是一樣。

三、設計程序
//拉暮式顯示數字1—8
 

DISP_CNT EQU 30H
TCNT     EQU 31H
       ORG 00H
       SJMP START
       ORG 0BH
       LJMP INT_T0
START: MOV DISP_CNT,#00H
       MOV TCNT,#00H
       MOV P2,#00H
       MOV TMOD,#01H
       MOV TH0,#(65536-5000)/256
       MOV TL0,#(65536-5000)MOD 256
       MOV IE,#82H
       SETB TR0
DISP:  MOV A,DISP_CNT
       MOV DPTR,#TABLE
       MOV R0,P2
       ADD A,R0
       MOVC A,@A+DPTR
       MOV P0,A
       LJMP DISP
INT_T0:MOV TH0,#(65536-5000)/256
       MOV TL0,#(65536-5000)MOD 256
       INC P2
       MOV A,P2
       CJNE A,#08H,RETUNE
       MOV P2,#00H
       INC TCNT
       MOV A,TCNT
       CJNE A,#10,RETUNE
       MOV TCNT,#00H
       INC DISP_CNT
       CJNE A,#15,RETUNE
       MOV P2,#00H
       MOV DISP_CNT,#00H
       MOV TCNT,#00H
RETUNE:RETI
TABLE: DB 00H,00H,00H,00H,00H,00H,00H
       DB 06H,5BH,4FH,66H,6DH,7DH,07H,7FH
       DB 00H,00H,00H,00H,00H,00H,00H,00H
       END      

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