Ultrasonic Distance Sensor

Ultrasonic Distance Sensor Module HC-SR04 provides a 2cm – 400cm non-contact measurement function, the ranging accuracy can reach 3mm. The modules include ultrasonic transmitters, receivers, and control circuits. The basic principle of work.This product use: a mouth sends a high level of more than ten us, you can receive the mouth for high-level output. To be able to open the timer timing, an output when the mouth into low electricity at ordinary times you can read the value of the timer is here for the distance of time can calculate the distance.
1. Using IO trigger for at least 10us high-level signal,
2. The Module automatically sends eight 40 kHz and detects whether there is a pulse signal back.
3. IF the signal is back, through high level, time of high output IO duration is the time from sending ultrasonic to returning.
4. Test distance = (high level time velocity of sound (340M/S) / 2