User Manual

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Lesson 10 Ultrasonic Sensor Module
Overview
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.
Component Required:
(1) x Elegoo Mega2560 R3
(1) x Ultrasonic sensor module
(4) x F-M wires (Female to Male DuPont wires)
Component Introduction
Ultrasonic sensor
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 range in proportion .You can calculate the range through the
time interval between sending trigger signal and receiving echo signal. Formula: us
/ 58 = centimeters or us / 148 =inch; or: the range = high level time * velocity
(340M/S) / 2; we suggest to use over 60ms measurement cycle, in order to prevent
trigger signal to the echo signal.