1. Use P1.0 to output 1KHz and 500Hz audio signals to drive the speaker as an alarm signal. It is required that the 1KHz signal sounds for 100ms and the 500Hz signal sounds for 200ms, alternately. P1.7 is connected to a switch for control. When the switch is closed, the alarm signal sounds. , when the switch is disconnected, the alarm signal stops and the program is programmed.
2. Circuit schematic diagram
The P1.0 port in the "MCU System" area is connected to the SPK IN port in the "Audio Amplification Module" area with a wire;
Connect an 8-ohm or 16-ohm speaker to the SPK OUT port in the "Audio Amplification Module" area;
Connect the P1.7/RD port in the "SCM System" area to the K1 port in the "Four-way Toggle Switch" area with a wire;
3. Program block diagram
4. Reference source program
FLAG BIT 00H
ORG 00H
START: JB P1.7, START
JNB FLAG, NEXT
MOV R2, #200
DV: CPL P1.0
LCALL DELY500
LCALL DELY500
DJNZ R2,DV
CPL FLAG
NEXT: MOV R2, #200
DV1: CPL P1.0
LCALL DELY500
DJNZ R2,DV1
CPL FLAG
SJMP START
DELY500: MOV R7, #250
LOOP： NOP
DJNZ R7,LOOP
RET
END
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