Keyestudio Micro:bit Mini Smart Robot Car V2 Instructions Manual page 93

When using it:
(1) Use IO trigger ranging, at least 10us HIGH level
signal; that is, first pull the Trip Low, then give a
HIGH level signal of 10us.
(2) The module automatically sends eight square
waves of 40khz to automatically detect whether
there is a signal return back;
(3) There is a signal return, through the IO output a
High level, and the duration period of High level is
the time of Ultrasonic wave from emission to return.
Test distance = (High level time * speed of sound (340M/S))/2;
Then you can get the formula: detection distance = (High level time/58) (cm);
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