Waveshare AlphaBot User Manual page 20

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AlphaBot User Manual
The timing diagram above shows the control principle of ultrasonic distance
measurement. When the module is working, it sends out a high level signal at least
for 10us to control the pin TRIG to trigger distance measurement. Then, the module
transmits 8 serial of 40kHz square wave automatically, to check whether there is
echo signal. If there is, the module outputs a high level voltage from the pin ECHO.
The time duration of the high level voltage is the time of ultrasonic from being
transmitted to reflected. According to the sound transmitting speed and time, we
can get that：measured distance=（measured time*sound speed）/2. The sound
speed is 340m/s in here.
Technical Parameters：
Parameters Remark Min Typ Max Units
Operating voltage 3.0 5.5 V
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