; This program multiplexes the number 1234 ; on the four 7-segment displays. ; Note: a logic 0 lights a display segment. start: SETB P3.3 ; | SETB P3.4 ; | enable display 3 MOV P1, #11111001B ; put pattern for 1 on display CALL delay CLR P3.3 ; enable display 2 MOV P1, #10100100B ; put pattern for 2 on display CALL delay CLR P3.4 ; | SETB P3.3 ; | enable display 1 MOV P1, #10110000B ; put pattern for 3 on display CALL delay CLR P3.3 ; enable display 0 MOV P1, #10011001B ; put pattern for 4 on display CALL delay JMP start ; jump back to start ; a crude delay delay: MOV R0, #200 DJNZ R0, $ RET