The low-cost US-100 ultrasonic sensor module is a compact, high-quality module for distance measurement. It can detect objects, obstacles, and walls up to a distance of 3.5-meters range. It is ideal for mobile robot applications. US-100 operation is based on reflective echo principle. A host microcontroller determines distance by triggering the US-100 module and then measuring the echo time indicated by the pulse width output of the sensor.     Contrast to the other ultrasonic ranging sensor, there is a build-in temperature sensor on the US-100 for accurate ranging even on varying ambient temperatures. Selected by the jumper, this sensor can also work in UART mode (band rate 9600) or GPIO mode, which makes you more convenient when making your applications.