蜂鸣器一直响很容易实现,无源蜂鸣器给电平就可以控制发声了,程序如下:
FMQ EQU P3.2ORG 0000HLJMP MAINORG 0030HMAIN: MOV A,#0FEH CLR FMQLOOP: MOV P1,A RL A LCALL DELAY SJMP LOOPDELAY: MOV R2,#200DLY: MOV R3,#250 DJNZ R3,$ DJNZ R2,DLY RET END