Wireless anti-theft alarm
First explain the production of the host in the wireless anti-theft alarm system. The AT89C2051 microcontroller is used as the central processing chip, which makes the system's function expansion more convenient. For the entire system, if you need to change a certain setting, you can change the corresponding software. It is very helpful for learning MCU.
hardware design
The circuit schematic diagram is shown in the following figure, which is mainly composed of wireless reception, data decoding, data processing, alarm circuit, output display, power failure alarm and power circuit. The receiving frequency of the whole machine is 315M, and the data decoding adopts the PT2272 dedicated decoding chip that is more commonly used in the market, and the reliability and stability are better; the data processing task is completed by the single-chip microcomputer, which is used to distinguish the alarm signal and accept various operation instructions. Complete the corresponding operation, after receiving the alarm signal, on the one hand, drive the alarm circuit to emit a loud police car alarm sound, on the other hand, output specific address information to determine which way to send the alarm signal; power failure alarm function monitors the power in real time The situation, when the mains power is cut off, it can emit a beeping alarm sound, which reminds the user that the external power supply has been cut off. If it is caused by the damage of the criminals, it can be prevented early. 
programming
The software design of the alarm is relatively simple, using AT89C2051 single-chip microcomputer. Interested netizens can develop corresponding functions according to their actual needs. Here, the basic procedures are listed for reference of netizens in need.
ORG 0000H;
CLR P1.6;
CLR P1.2;
ACALL DYS;
SETB P1.6
ACALL YS;
SETB P1.2;
CLR P1.3;
CLR P1.6;
ACALL DYS;
SETB P1.6;
ACALL YS;
SETB P1.3;
CLR P1.4;
CLR P1.6;
ACALL DYS;
SETB P1.6;
ACALL YS;
SETB P1.4;
CLR P1.5;
CLR P1.6;
ACALL DYS;
SETB P1.6;
ACALL YS;;
MOV P1, # 0FFH;
MOV P3, # 0FFH;
AGARN: MOV R6, # 34H;
JB P3.6, TINDIAN; Check if there is a power outage
JNB P3.0, AGARN; Is there a valid wireless signal input
ACALL DYS;
JNB P3.0, AGARN;
MOV A, P3; read wireless signal value
ANL A, # 3CH; 0011,1100
CJNE A, # 20H, XH; 20H = 00 (10,00) 00 B
; Disarm procedures
CLR P3.1;
CLR P1.6; successful response to disarm
CLR P1.4; indicator
CLR P1.5;
SETB P3.7;
ACALL YS;
SETB P1.6;
AJMP AGARN;
XH: CJNE A, # 30H, ONE; judge whether it is arming signal
SETB P3.1;
CLR P1.6; successful response
SETB P1.4; indicator
SETB P1.5;
SETB P3.7;
ACALL YS;
SETB P1.6;
AJMP AGARN;
ONE: JNB P3.1, AGARN;
CJNE A, # 4H, TWO; 1H = 00 (00,01) 00B
MOV P1, # 0FBH;
AJMP BJ;
TW CJNE A, # 8H, THREE; 2H = 00 (00,10) 00B
MOV P1, # 0F7H;
AJMP BJ;
THREE: CJNE A, # 0CH, FOUR; 3H = 00 (00,11) 00B
MOV P1, # 0EFH;
AJMP BJ;
FOUR: CJNE A, # 10H, FIVE; 00 (01,00) 00B
MOV P1, # 0DFH;
AJMP BJ;
FIVE: NOP;
NOP;
NOP;
AJMP AGARN;
BJ: CLR P3.7; start alarm signal
ACALL YS; Delay 34 seconds
JB P3.0, AGARN;
DJNZ R6, BJ;
SETB P3.7; close the alarm signal
AJMP AGARN;
TINDIAN: MOV P1, # 0FFH; power outage procedure
CLR P1.6;
CLR P1.5;
ACALL YS;
SETB P1.6;
SETB P1.5;
ACALL YS;
CLR P1.6;
CLR P1.5;
ACALL YS;
SETB P1.6;
SETB P1.5;
ACALL YS;
AJMP AGARN;
DYS: MOV R0, # 14H;
L1: MOV R1, # 0F1H;
L2: NOP;
NOP;
NOP;
DJNZ R1, L2;
DJNZ R0, L1;
RET
YS: MOV R0, 0FFH;
L3: MOV R1, 0F1H;
L4: NOP;
NOP;
NOP;
DJNZ R1, L4;
DJNZ R0, L3;
RET;
END;
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