1min取反

11H490

ORG 00H
LJMP MAIN
ORG 30H
MAIN:JB P2.3,MAIN
MOV P1,#0BEH
MOV P2,#0BEH
MOV 30H,#20
MOV 31H,#5
MOV TMOD,#10H
MOV TH1,#3CH
MOV TL1,#0B0H
MOV IE,#00H
SETB TR1
L0:JBC TF1,L1
AJMP L0
L1:MOV TH1,#3CH
MOV TL1,#0B0H
DJNZ 30H,L0
MOV 31H,#5
CPL P1.0
AJMP L0
END