Build an Ultrasonic Parking Sensor with ESP32
Intermediate
Est. Time: 2 hours
Est. Total: $21.41
Build a distance-sensing system that uses the HC-SR04 ultrasonic sensor to detect objects and provide visual and audible proximity warnings — just like the parking sensors in modern cars. The NE555 generates a beeping tone that speeds up as objects get closer. The ESP32's WiFi lets you add a live distance readout on your phone. A hands-on project that teaches distance measurement, signal processing, and output control.
Bill of Materials — Available in Our Shop
| Part | Qty | Price | Total | Status |
|---|---|---|---|---|
| ESP32-WROOM-32 DevKit (38-Pin, USB-C) Microcontroller — processes distance data and controls alarm rate |
1 | $8.99 | $8.99 | In Stock |
| HC-SR04 Ultrasonic Distance Sensor Distance measurement — detects objects from 2 to 450cm |
1 | $2.49 | $2.49 | In Stock |
| NE555 Timer IC (DIP-8) Beep generator — variable-rate proximity warning tone |
1 | $0.99 | $0.99 | In Stock |
| 830-Point Breadboard + Jumper Wires + Power Supply Kit Prototyping platform with power supply and jumper wires |
1 | $7.99 | $7.99 | In Stock |
| Subtotal (from our shop) | $20.46 | |||
Additional Parts Needed
These common parts are available at most electronics retailers. Estimated prices shown for budgeting.
| Part | Qty | Est. | Total |
|---|---|---|---|
| Piezo Buzzer | 1 | $0.50 | $0.50 |
| 3x LEDs (green, yellow, red) | 1 | $0.30 | $0.30 |
| 3x 220 ohm Resistors | 1 | $0.15 | $0.15 |
| Est. external subtotal | $0.95 | ||
Parts from our shop$20.46
Est. external parts$0.95
Est. Project Total$21.41
Step-by-Step Instructions
- Mount the HC-SR04 sensor on the breadboard. Connect VCC to 5V, GND to GND, Trig to ESP32 GPIO 5, and Echo to ESP32 GPIO 18.
- Wire three LEDs through 220 ohm resistors to ESP32 GPIO 26 (green), GPIO 27 (yellow), and GPIO 14 (red). These indicate proximity zones.
- Build the NE555 alarm circuit on the breadboard. Connect ESP32 GPIO 25 to the NE555 reset pin to control beeping.
- Upload the ESP32 sketch via USB-C: send a 10-microsecond pulse on Trig, measure the Echo return time, and convert to centimeters using the speed of sound formula (duration / 58).
- Program three distance zones: green LED for objects beyond 100cm, yellow LED for 30-100cm with slow beeping, red LED for under 30cm with rapid beeping. Optionally add a WiFi web server to display live distance readings on your phone.
- Mount the sensor facing outward on a wall or post. Test by walking toward it and verifying the LED transitions and beep rate changes match the expected zones.