它和LED的原理是一样，在要亮的输出口供电。把输出口的位接到七段显示器的相对应接位。但七段显示器就需要注意供电给每一个位后，可否做到你想做的字或符号。
利用七段显示器来显示计数器从00数到16
;port 1 connect to 7 segment
;.,a,b,c,d,e,f,g
;port 3.0 and 3.1 connect to 2 npn transitor
;delay=1s

.ORG 0000H
START: MOV R1, #(OK-TABLE)/2
MOV DPTR, #TABLE
REPEAT: MOV R2, #250
SCAN: ACALL SCAN1
DJNZ R2, SCAN
INC DPTR
INC DPTR
DJNZ R1, REPEAT
AJMP START
;===========
;= SCAN1 =
;===========
SCAN1: MOV R5, #11111101B
MOV R4, #02
MOV R0, #00H
LOOP: MOV A, R0
MOVC A, @A+DPTR
MOV P1, A
INC R0
MOV P3, R5
ACALL DELAY
ORL P3, #11111111B
MOV A, R5
RR A
MOV R5, A
DJNZ R4, LOOP
RET
;===========
;= DELAY =
;===========
DELAY: MOV R6, #5
DL1: MOV R7, #197
DL2: DJNZ R7, DL2
DJNZ R6, DL1
RET
TABLE: .DB 01000000B, 01000000B 
.DB 01000000B, 01111001B
.DB 01000000B, 00100100B
.DB 01000000B, 00110000B
.DB 01000000B, 00011001B
.DB 01000000B, 00010010B
.DB 01000000B, 00000010B
.DB 01000000B, 01111000B
.DB 01000000B, 00000000B
.DB 01000000B, 00010000B
.DB 01111001B, 01000000B
.DB 01111001B, 01111001B
.DB 01111001B, 00100100B
.DB 01111001B, 00110000B
.DB 01111001B, 00011001B
.DB 01111001B, 00010010B
.DB 01111001B, 00000010B
OK:
.END