A List of Shopping Parts In this tutorial we will study how we can measure the distance accurately using a HC-SR04 Ultrasonic range sensor and Raspberry PI.For this work we want following materials: HC-SR04 Ultrasonic range sensor :₹ 150 Resistors: ₹2 Raspberry Pi Jumper Wires Ultrasonic Ranging Module HC-SR04 Ultrasonic module Ultrasonic ranging module HC-SR04 provides 2cm-400cm non-contact measurement function ranging accuracy can reach to 3mm. The module includes ultrasonic transmitters, reciever, crystal and control unit. The basic priciple of work is: Using trigger for at least 10μs high level signal. The module automatically sends eight 40kHz and detect whether there is a pulsesignal back. If the signal back, through high level, time of high output IO duration is the time from sending ultrasonic to returning. Test distance=(high level time x velocity of sound)/2 From the pre-primary classes we are studied that the distance is time x distance