Item specifics
Description
HC-SR04 Ultrasonic Distance Sensor Module Product Overview
The HC‑SR04 is a classic ultrasonic distance sensor module based on the CS100A chip. It emits 40kHz ultrasonic pulses and measures the echo return time to calculate the distance to an object. Operating from 3-5.5V, it features a simple Trig/Echo interface: a ≥10µs high pulse on Trig triggers the module to send eight 40kHz bursts, and the Echo pin outputs a high pulse whose width corresponds to the round‑trip time. The distance can be calculated as (high pulse duration × speed of sound (340m/s)) / 2. Range is 2cm to 4m. The compact module measures 45.2×20×14.5mm and weighs 8g. Ideal for robot obstacle avoidance, liquid level sensing, smart cars, and other distance measurement applications.
HC-SR04 Ultrasonic Distance Sensor Module Core Features
CS100A Chip Solution： Integrated ultrasonic transmit/receive control and signal processing for stable, consistent performance
Simple Trigger/Echo Interface： Uses only two I/O pins (Trig and Echo), compatible with Arduino, STM32, 8051, and other MCUs
Wide Measurement Range： 2cm minimum to 4m maximum, covering most robot obstacle avoidance and short‑range distance sensing needs
Wide Operating Voltage： 3-5.5V DC, works with both 3.3V and 5V microcontroller systems – no level shifting required
Accurate Ranging： Distance = (high pulse duration × 340m/s) / 2, achieving cm‑level accuracy with an MCU timer
Periodic Measurement： Recommended interval ≥60ms, supports continuous moving measurement for real‑time distance updates
Low Power： Low standby current suitable for battery‑powered portable devices
HC-SR04 Ultrasonic Distance Sensor Module Applications
Robot Obstacle Avoidance： Front‑mounted on smart cars or robots to detect obstacles and trigger steering or stopping
Liquid Level Detection： Non‑contact measurement of water tank or tower levels
Smart Car Following： Measure distance to a leading object for automatic following
Drone Altitude Hold： Low‑altitude ground distance measurement for hovering stability
Simple Reverse Radar： Inexpensive parking assistance
Teaching & Experiments： Distance sensor labs in microcontroller courses
HC-SR04 Ultrasonic Distance Sensor Module Key Advantages
Classic, Mature, Widely Used： HC‑SR04 is the most popular ultrasonic distance module – extensive tutorials and open‑source code, low learning curve
Simple Interface, Plug‑and‑Play： Only two I/O pins; trigger with a 10µs high pulse and read the Echo pulse width – perfect for beginners
Wide 3.3V/5V Compatibility： 3-5.5V supply works directly with Arduino (5V) and ESP32/STM32 (3.3V) – no extra converters
Non‑contact Measurement, Media‑independent： Uses ultrasound, unaffected by object colour or transparency; works on liquids and solids
Low Cost, High Performance： Significantly cheaper than laser rangefinders while meeting most obstacle avoidance and short‑range needs
Compact and Light, Easy to Integrate： 45×20mm footprint, 8g weight, fits easily on robots, cars, or inside devices
Fast Response, Real‑time Capability： Auto‑burst on trigger, quick echo detection – suitable for dynamic distance sensing
Rich Learning Resources： Vast example code for Arduino, STM32, Raspberry Pi – quick to get started
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FAQ:
What is the HC-SR04 ultrasonic distance sensor and how does it work?
The HC-SR04 is a widely used ultrasonic ranging module that measures distance by emitting 40 kHz ultrasonic pulses and listening for their echo. The on-board controller sends a short 10 µs trigger pulse, and the module responds with a pulse whose width is proportional to the round-trip time of the sound wave. By measuring this pulse width and applying the formula Distance = (Pulse Width × Speed of Sound) / 2, you can calculate the distance to an object. It requires only two GPIO pins (TRIG and ECHO) and is compatible with virtually any microcontroller, including Arduino, ESP32, and Raspberry Pi.
What is the voltage range of this HC-SR04 module, and can it work with both 3.3 V and 5 V systems?
This wide-voltage version accepts a supply voltage from 3 V to 5.5 V DC, making it directly compatible with both 3.3 V microcontrollers (ESP32, Raspberry Pi, nRF52) and 5 V boards (Arduino Uno, Mega). The TRIG input is 3.3 V‑tolerant, and the ECHO output swings to the supply rail. For 3.3 V systems with strict I/O limits, you can power the module at 3.3 V and use the ECHO pin directly; for 5 V systems, power the module at 5 V for maximum range and use a simple voltage divider on the ECHO pin if your MCU is not 5 V‑tolerant.
How does this wide-voltage HC-SR04 differ from the standard blue HC-SR04? Is it really industrial grade?
The wide-voltage variant typically uses a different PCB color (often black or green) and features an upgraded transducer and driver circuit that operate reliably from 3 V to 5.5 V, whereas the classic blue HC-SR04 requires 5 V and may malfunction below 4.5 V. The “industrial grade” designation generally refers to improved environmental tolerance, better temperature stability, and more consistent ranging performance compared to the consumer‑grade blue modules. It often includes additional filtering components and a more robust transducer bonding for long‑term reliability in outdoor or factory environments.
What is the typical measuring range and accuracy of the HC-SR04 sensor?
The effective measuring range is approximately 2 cm to 400 cm (4 m), with a resolution of about 3 mm and an accuracy of ±3 mm under ideal conditions. The minimum reliable distance is around 2 cm due to the transducer ring‑down time. The maximum range and accuracy are affected by the target’s size, shape, and material—soft, angled, or sound‑absorbing surfaces reduce the echo strength and the maximum measurable distance. The sensor performs best with hard, flat surfaces perpendicular to the ultrasonic beam.
How do I connect the HC-SR04 to an Arduino? Which pins should I use?
Connect VCC to the Arduino’s 5 V pin (or 3.3 V for the wide‑voltage version), GND to GND, TRIG to any digital output pin (e.g., D9), and ECHO to any digital input pin (e.g., D10). If you are using a 3.3 V Arduino and powering the sensor at 5 V, you must protect the ECHO pin with a 1 kΩ/2 kΩ voltage divider to reduce the 5 V signal to a safe 3.3 V level. The NewPing library or the standard Arduino pulseIn() function can be used to read the echo pulse width.
Why does my HC-SR04 give inaccurate or zero readings, and how can I fix it?
Common causes include: (1) the target is too close (less than 2 cm), causing the transducer ring‑down to mask the echo; (2) the target surface is soft, angled, or irregular, absorbing or scattering the sound; (3) the sensor is triggered too frequently, not allowing the echo to return before the next trigger; (4) electrical noise from the power supply or long wires couples into the ECHO line. To fix these, ensure the target is at least 3 cm away, use a hard flat surface, insert a 60 ms delay between measurements, and add a small capacitor (100 nF) across the VCC and GND pins close to the sensor. The NewPing library handles the maximum‑range timeout better than the standard pulseIn() approach.
Can this sensor be used outdoors, and how does temperature affect the readings?
The HC-SR04 can be used outdoors, but its performance is affected by wind, temperature, and humidity. The speed of sound changes by approximately 0.6 m/s per degree Celsius, which causes a distance error of about 0.2 % per degree. At 0 °C versus 30 °C, the error can reach several percent. For outdoor applications with large temperature swings, you can add a temperature sensor (e.g., DS18B20) and apply the corrected formula: Speed of Sound = 331.3 + 0.606 × Temperature_°C. The sensor is not waterproof and must be protected from rain and condensation.
How much current does the HC-SR04 draw, and can I use it in a battery‑powered device?
The sensor draws about 2 mA in standby and 15 mA during an active measurement. This is low enough for most battery‑powered applications. To conserve power, you can switch the sensor’s VCC line using a MOSFET or a GPIO pin (if the sensor’s current is within the pin’s drive capability, which is marginal). Since a measurement completes in a few tens of milliseconds, you can power the sensor only when needed, take a reading, and then cut power to extend battery life significantly.
Can I use multiple HC-SR04 sensors in the same project without interference?
Yes, but you must prevent crosstalk between sensors. The simplest method is to trigger only one sensor at a time, wait for its echo to complete, and then trigger the next sensor. If you need simultaneous or overlapping measurements, you can use the “NewPing” library which supports up to 15 sensors with individual trigger/echo pins and manages the timing automatically. Alternatively, you can physically separate the sensors and angle them away from each other, but software sequencing is far more reliable.
What are the most typical applications for this industrial‑grade wide‑voltage HC-SR04 sensor?
It is used in warehouse inventory robots, parking sensors, autonomous guided vehicles (AGVs), liquid level monitoring, conveyor‑belt object detection, drone altitude hold, and smart trash bins. Its wide voltage compatibility, improved reliability, and consistent performance make it a staple for both rapid prototyping and low‑volume industrial installations where a cost‑effective, non‑contact distance sensor is required.