LED turns on when an object is detected within 20cm using an ultrasonic sensor.
An HC-SR04 ultrasonic sensor measures distance in real time. When an object comes within 20cm, an LED is triggered on. Distance is printed to the Serial Monitor for debugging.
- Arduino Uno
- 1x HC-SR04 Ultrasonic Sensor
- 1x LED
- 1x 220Ω resistor
- Breadboard + jumper wires
| Component | Arduino Pin |
|---|---|
| HC-SR04 Trig | Pin 9 |
| HC-SR04 Echo | Pin 10 |
| HC-SR04 VCC | 5V |
| HC-SR04 GND | GND |
| LED (+) | Pin 6 |
| LED (-) | GND via 220Ω resistor |
- Ultrasonic sensor interfacing (HC-SR04)
- Pulse timing with
pulseIn() - Distance calculation
- Serial Monitor debugging
- Sensor-triggered output