What is an Ultrasonic Module HC-SR04 Distance Sensor?

 This is a sensor that can be used to measure the distance between itself and an object.And Ultrasonicranging module HC-SR04 provides 2cm-400cm non-contact, measurementfuncktion the ranging accuracy can reach to 3mm. The module HC-SR04 includes ultrasonic transmitters,receiver and control circuit. Compared to the Shap IR ranging module, HC-SR04 is more inexpensive than it. But it has the same ranging accuracy and longer ranging distance.

Where to buy the similar sensor modules?

 Of course, you will search many kinds of the products online.However, maybe the most difficult thing is how to make a choice.Here I provide you a good platform named Yasurs, in which you will gain much more surprise.

What is the basic principle of work?

 Using IO triggerfor at leasr 10us high level signal. The module automatically sends eight 40kHz and detect whether there is a pulse signal back. If the signal back,through high level, time of high output IO duration is the time from seeding ultransonic to returning. The distance=[high level time×velocity of sound(340m/s)] /2.