Ultrasonic Module HC-SR-04

This ultrasonic sensor module is used for measuring distance, object sensors, motion sensors, etc. Ultrasonic Sensor HC-SR04 uses sonar to measure the distance of the object. It emits an ultrasonic wave at 40 kHz which will go and bounce back after hitting an object. By knowing the time travelled and the speed of the sound, we can calculate the distance (speed=distance/time). Ultrasonic waves are much faster than regular sound and as humans, we won’t be able to hear them. (Some animals and fishes like dolphins and bats are able to use it for communication and seeing in the dark).

An ultrasonic sensor detects and measures the distance of a target object using ultrasonic sound waves and converts the reflected sound into an electrical signal. This sensor has 4 pins which are VCC, TRIG, ECHO, GND. The two main components of this sensor are the transmitter and receiver. Hence the transmitter produces the sound and the receiver, receives it. The voltage pin VCC connected to 5V and the GND connected to the ground and the trig and echo connected to the GPIO pins.

To generate the ultrasound, the Trig set to a high state for a time of 10 µs. In response to it, the sensor transmits an 8 cycle sonic burst at 40KHz. This will travel at the speed of sound and it will be received in the Echo pin. The Echo pin goes high and will output the time in microseconds of the sound wave travelled. As soon as the signal is received, the echo pin goes low.