Human infrared sensor

Main Functions:

1. The main unit has four control buttons: one for arming, one for emergency alarm, one for disarming, and one for microcontroller reset. The reset button is optional.
2. After pressing the arming button, it enters monitoring mode after 30 seconds (no alarm during this time). After 30 seconds, when someone approaches, the pyroelectric infrared sensor detects the signal and transmits it back to the microcontroller, which immediately triggers an alarm. Pressing the disarming button de-arms the system.
3. In case of a special emergency, pressing the emergency alarm button will trigger the buzzer. (This requires the unit to be in arming mode!!!)
4. When arming, the digital display shows "b"; when disarming, it shows "c"; and when an alarm is triggered, it shows "-".
Functionality: The digital display turns off after the arming button is pressed.
Waiting State: After pressing the arming button, the digital tube displays the letter "b" for 30 seconds, after which the display goes out, indicating that the system is in armed state. The 30-second countdown from button press to the end can be extended by repeatedly pressing the arming button; the countdown does not accumulate and the system will reset to 30 seconds. The disarming button can also be pressed to cancel arming.
Armed State: When the sensor module has a signal, the digital tube displays the number "-" and the buzzer sounds an alarm.
Alarm State: Pressing the disarming button displays the letter "c" on the digital tube, the buzzer stops sounding, and the system enters the waiting armed state.
Emergency State: When the system is in armed state, the SOS button can be pressed to activate the alarm; the buzzer sounds, and the digital tube displays the number "-".
PCB Description:
This system uses an STC89C52 DIP40 package; using an LQFP44 would be smaller and easier to conceal. Placing it near your home would be a good choice!
Physical Demonstration:
This device was used in a competition; a 3D printed shell was created. See attachment for details.
Demonstration video
is also attached.