Lesson 6 Ultrasonic Sensor Module
About this lesson:
Ultrasonic sensor is great for all kind of projects that need distance measurements, avoiding obstacles as examples.
The HC-SR04 is inexpensive and easy to use since we will be using a Library specifically designed for these sensor.
Introduction:
Ultrasonic sensor 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:
(1) Using IO trigger for at least 10us high level signal,
(2) The Module automatically sends eight 40 kHz and detect whether there is a pulse signal back.
(3) IF the signal back, through high level , time of high output IO duration is the time from sending ultrasonic tore turning.
Test distance = (high level time × velocity of sound (340m/s) /2
The Timing diagram is shown below. You only need to supply a short 10us pulse to the trigger input to start the ranging, and then the
module will send out an 8 cycle burst of ultrasound at 40 kHz and raise its echo. The Echo is a distance object that is pulse width and the
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