HC-SR04 Ultrasonic Sensor Distance Module, for All Type of Devlopment Board and robot Ultrasonic sensor - ultrasonic sensor provides an easy method of distance measurement. This sensor is perfect for any number of applications that require you to perform measurements between moving or stationary objects. A single I/O pin is used to trigger an ultrasonic burst (well above human hearing) and then "listen" for the echo return pulse. The sensor measures the time required for the echo return, and returns this value to the microcontroller as a variable-width pulse via the same I/O pin. Buy Now Ultrasonic Ranging Detector Mod HC-SR04 Distance Sensor (Blue) HC-SR04 Arduino ultrasonic sensor can send eight 40 kHz and detect whether there is any pulse signal back.If it back, a high level signal will be outputed by IO, and the duration of the signal is the time from sending ultrasonic to returning. The modules in...