HC-SR04 Ultrasonic Distance Sensor

The HC-SR04 Ultrasonic Distance Sensor Module is one of the most popular and affordable ranging sensors for electronics projects in India. It measures distance without touching the target, making it a practical choice for robot navigation, object detection, tank level estimation, smart dustbins, parking sensor prototypes, and classroom experiments. The module integrates an ultrasonic transmitter, ultrasonic receiver, and control circuit on a small PCB, so designers can add distance sensing with only four pins: VCC, Trig, Echo, and GND. Operation is simple and well documented. A microcontroller sends a trigger pulse of at least 10 µs to the Trig pin. The HC-SR04 automatically transmits a burst of eight 40 kHz ultrasonic pulses and then raises the Echo output for the time taken by the sound wave to travel to the object and return. Your controller measures this pulse width and converts time-of-flight into distance. The sensor supports a measurement range of approximately 2 cm to 400 cm, with typical ranging accuracy up to 3 mm under suitable conditions. This HC-SR04 ultrasonic module is designed for 5V operation and provides a TTL digital output, making it straightforward to connect to Arduino UNO, Nano, Mega, and many 5V development boards. When using 3.3V boards such as ESP32, ESP8266, Raspberry Pi Pico, or Raspberry Pi GPIO, use a resistor divider or logic level shifter on the Echo pin because the Echo signal is 5V. For best readings, keep the sensor face clear, avoid soft/angled surfaces that absorb or deflect sound, and allow a measurement cycle of around 60 ms or more between triggers. In the box: 1 x HC-SR04 Ultrasonic Distance Sensor Module. Header pins are pre-fitted on most standard modules, and jumper wires are sold separately unless mentioned in a kit.