HC-SR04 Ultrasonic Distance Sensor Module (5V, 2-450cm)

Specifications

• Operating Voltage: 5V DC

• Operating Current: 15mA

• Operating Frequency: 40KHz

• Minimum Measuring Distance: 2cm

• Maximum Measuring Distance: 450cm

• Measuring Angle: < 15 degrees

• Trigger Input Signal: 10µS TTL pulse

• Echo Output Signal: TTL pulse directly proportional to distance

• Dimensions: 45 x 20 x 15mm

Downloads & Links

• Ultrasonic Sensor HC-SR04 and Arduino Tutorial
• HC-SR04 Ultrasonic Sensor
• Simple Arduino and HC-SR04 Example
• Complete Guide for Ultrasonic Sensor HC-SR04 with Arduino

Key Applications and Projects

• Obstacle Avoidance: Mounting the sensor on the front of an RC car to detect walls and automatically steer away from collisions.

• Smart Trash Cans: Placing the sensor inside a lid to detect when a hand approaches, triggering a servo motor to open the bin automatically.

• Tank Level Monitoring: Installing the module at the top of a water tank or silo to measure the distance to the liquid surface, calculating remaining capacity.

Unlock New Capabilities (Project Evolution) The 180-Degree Radar Scanner: A single HC-SR04 only sees straight ahead, but you can upgrade its vision! By mounting this sensor onto the horn of a standard SG90 Micro Servo, you can sweep the sensor back and forth. Write a simple Arduino sketch that takes a distance reading at every 1-degree interval of the servo's rotation. Send this data over serial to your computer, and you can plot a real-time, 180-degree 2D sonar radar map on your screen using Processing!

PACKAGE INCLUDED

• 1 x HC-SR04 Ultrasonic Distance Sensor Module

FREQUENTLY ASKED QUESTIONS (FAQ)

1. What are the physical dimensions of the HC-SR04 module? The module has a width of 45mm and a height of 20mm.

2. What do the "T" and "R" labels under the cylinders stand for? The "T" indicates the Transmitter for Ultrasonic Waves, while the "R" indicates the Receiver for Ultrasonic Waves.

3. What is the silver oval component located at the top center of the board? That component is a 4 MHz Crystal Oscillator used for precise acoustic timing.

4. What voltage does this sensor require to operate? The HC-SR04 is designed to be powered by a +5V supply via the Vcc pin.

5. How many pins does this sensor have? It features a standard 4-pin header.

6. What is the function of the Trig pin? The Trig (Input Pin) is used by your microcontroller to send a 10-microsecond signal that tells the module to fire its ultrasonic burst.

7. What is the function of the Echo pin? The Echo (Output Pin) sends a TTL pulse back to your microcontroller; the length of this pulse represents the time it took for the sound wave to bounce back.

8. Can I use this with a 3.3V microcontroller like a Raspberry Pi or ESP32? While you can trigger the sensor with a 3.3V signal, it requires 5V to power up properly and will output a 5V signal on the Echo pin. You must use a voltage divider or logic level converter on the Echo line to avoid damaging a 3.3V input pin.

9. What is the effective measuring range? The sensor can reliably measure distances starting from 2cm up to 450cm.

10. How do I calculate distance from the Echo pulse? Measure the time of the Echo pulse in microseconds, multiply by 0.0343 (speed of sound in cm/µs), and divide by 2 (to account for the round trip) to get the distance in centimeters.

11. Is this sensor waterproof? No, the standard HC-SR04 features exposed wire mesh on the transmitter and receiver, making it unsuitable for wet or outdoor conditions.

12. Can it detect transparent objects like glass? Yes. Because it uses sound waves rather than light, it easily detects clear materials like glass or transparent plastics that optical sensors miss.

13. Does the shape of the target object matter? Yes. Large, flat, solid surfaces facing directly at the sensor provide the best echoes. Highly angled surfaces can deflect the sound wave away from the receiver.

14. Are there mounting holes on the board? Yes, the PCB features four circular mounting holes, one in each corner, for simple physical installation.

15. What components are on the back of the board? The rear of the PCB houses the signal processing circuitry, typically including operational amplifiers like the LM324.

16. What is the measuring angle (cone of detection)? The effective measuring angle is relatively narrow, at roughly 15 degrees.

17. How fast can I trigger the sensor? It is recommended to wait at least 60 milliseconds between trigger pulses. Firing it too quickly can result in overlapping echoes and false readings.

18. Will temperature affect my distance readings? Yes, the speed of sound changes slightly depending on the ambient air temperature. For extreme precision, add a temperature sensor to your project to compensate mathematically.

19. Can I use multiple HC-SR04 sensors on the same robot? Yes, but you must trigger them sequentially (one after the other with a delay), rather than simultaneously, to prevent their sound waves from interfering with each other's receivers.

20. Does the sensor emit visible light or audible sound? No, it operates at 40KHz, which is an ultrasonic frequency completely invisible to the eye and inaudible to the human ear.