How to set up the Hc-SRO4 Ultrasonic Range Sensor  I got 2 of these a week ago there great but there not much on how to set them up so I figured I share how I did it. First off you have to wire it up which from what I have read people was doing it wrong more then once. So here is how I got it to work . I added the serial file so you can use the Serial Monitor to get reading in cm. The zip file has all you need to get this work. Pin 9 is used for trig pin 10 is used for echo. Vcc to 5 volt pin on the arduino. And gnd to gnd on the arduino. Here a picture to make it easy Great little range finder at great price  The files you need to add to the arduino ide are here  http://sites.google.com/site/be80be/be80be-pic-ing-howto-s/hc-sr04-ultrasonic-range-sensor/HCSR4DemoArduino.zip?attredirects=0&d=1