ULTRA SONIC HC 04
Ultrasonic ranging module HC - SR04 provides 2cm - 400cm non-contact measurement function, the ranging accuracy can reach to 3mm.The modules includes ultrasonic transmitters, receiver and control circuit.The basic principle of work
The HC-SR04 ultrasonic sensor uses sonar to determine distance to an object like bats do. It offers excellent non-contact range detection with high accuracy and stable readings in an easy-to-use package. From 2cm to 400 cm or 1” to 13 feet. It operation is not affected by sunlight or black material like Sharp rangefinders are (although acoustically soft materials like cloth can be difficult to detect). It comes complete with ultrasonic transmitter and receiver module.
Using IO trigger for at least 10us high level signal,
The Module automatically sends eight 40 kHz 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 sending ultrasonic to returning.