HC-SR04 Ultrasonic Distance Sensor

Non-Contact Obstacle Detection and Ranging Module

The HC-SR04 is an affordable ultrasonic distance sensor that measures object distance by emitting 40kHz sound waves and timing the echo return. It is perfect for obstacle avoidance robots, proximity detection, and level monitoring in DIY projects. [citation:4][citation:10]

Technical Specifications

= Pin Configuration =

= Key Features =

NonContact Measurement Detects objects without physical contact [citation:1]

Fast Response - Outputs echo pulse proportional to distance

Low Power Consumption - 15mA operation [citation:1][citation:2]

Precise Timing - Pulse width ranges from 150µs to 25ms [citation:1]

= Applications =

1. Obstacle avoiding robots [citation:5]
2. Distance measuring devices
3. Parking sensors
4. Level and proximity detection
5. Interactive installations

√ Compatible with Arduino, ESP32, and Raspberry Pi [citation:3]

√ Works with standard distance calculation libraries

√ Includes 4-pin header for easy connection

Distance Calculation

Distance = (Echo pulse width × 0.034 cm/µs) / 2 [citation:1][citation:7]

Troubleshooting

No reading:

• Verify stable 5V power
• Check trigger and echo pin connections
• Avoid using in environments with high ultrasonic noise

Inaccurate readings:

• Ensure target is within 2-400cm range [citation:1]
• Keep beam perpendicular to target surface
• Use 60ms or longer measurement cycles [citation:12]