单片机24秒倒计时c语言,单片机汇编语言24秒倒计时程序

;24秒倒计时

ORG 0000H

LJMP M1 ORG 000BH LJMP N1 ORG 0100H

M1: MOV R7,#20

MOV TMOD,#01H MOV TH0,#4CH

MOV TL0,#00H SETB ET0 SETB EA SETB TR0

MOV 70H,#04H

MOV 71H,#02H

MOV 30H,#24H L1: MOV DPTR,#TAB

MOV P2,#0FEH

MOV A,70H

MOVC A,@A+DPTR MOV P0,A

LCALL DEL

MOV P2,#0FDH

MOV A,71H

MOVC A,@A+DPTR MOV P0,A

LCALL DEL

SJMP L1

N1: DJNZ R7,M4

MOV R7,#20

MOV A,30H

CJNE A,#00H,M3

MOV A,#24H

MOV 30H,A

SJMP CHAI

M3: CLR C

ADD A,#99H

DA A

MOV 30H,A