Door alarm

Step 1: Build the circuit. The circuit is relatively simple.

Ultrasonic sensor:

GND to GND

VCC to 5V

ECHO to D2

TRIG to D3

Buzzer:

+ to D9

- to GND

LED

+ to D13

- To GND

Step 2: Upload the Code

Thank you to abdularbi17 for part of the code ( https://create.arduino.cc/projecthub/abdularbi17/ultrasonic-sensor-hc-sr04-with-arduino-tutorial-327ff6?ref=user&ref_id=1134675&offset=0 )

Step 3: Put it in a box and attach it to the doorframe deppending on the width you might need to edit the if statment.

Thank you!