;viet ct tao xung vuong 1khz, chu ky nhiem vu 50% tren chan p3.0 ;xung 1khz co chu ky la 1000us, dc 50% nen time muc 1= muc 0= 500us ;su dung lenh djnz het 2MCs=2x12/11.0592=2.17us => lap lai 500/2.17= 230 lan ORG 2000H LAP: CPL P3.0 MOV R7,#230 DJNZ R7,$ SJMP LAP END