This popular ultrasonic distance sensor provides stable and accurate distance measurements from 2cm to 450cm. It has an focus of less than 15 degrees and an accuracy of about 2mm. Features Usage: Connect the VCC and GND pins to a 5V power supply, the trigger input (Trig) pin to a digital output and the echo (Echo) pin to a digital input on your robot's microcontroller. Pulse the trigger (Trig) pin high for at least 10us (microseconds) and then wait for a high level on the echo (Echo) pin. The amount of time it takes to receive the echo corresponds to the distance that the ultrasonic sound has travelled. The quicker the response, the closer your robot is to an obstacle.