Kart/sensors/HCSR04

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(Ultrasound ranger)
(Ultrasound ranger)
 
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:: <math>distance = count \cdot 0.0017 ~ [cm]</math>
 
:: <math>distance = count \cdot 0.0017 ~ [cm]</math>
  
There is approximately 500 us between the trigger and the start of the answer. Moreover, for ranges of about 20-30 cm, the return signal duration is of an order of 2 ms. Thus, going above 10 ms (100Hz) for the whole measure is not a good idea.
+
There is approximately 500 us between the trigger and the start of the answer.
 +
Moreover, for ranges of about 20-30 cm, the return signal duration is of an order of 2 ms.
 +
Thus, a measurement cycle should take at least something like 10 ms, achieving a maximal measurement rate of about 100Hz.
  
 
[[Category:Kart]]
 
[[Category:Kart]]

Latest revision as of 08:19, 24 August 2016

Contents

Ultrasound ranger

The elecfreaks Ultrasonic sensor distance measuring module receives a trigger pulse, startMeasure, sends an ultrasonic pulse train and then provides a pulse, distancePulse, whose length is proportional to the sound flight and echo time.

Ultrasound ranger.svg

It has a dedicated connector on the I/O board.

The ultrasoundRanger block in the sensors FPGA counts the ultrasonic pulse length in terms of the 10 MHz clock periods. The distance is thus given by:

distance = count \cdot 0.0017 ~ [cm]

There is approximately 500 us between the trigger and the start of the answer. Moreover, for ranges of about 20-30 cm, the return signal duration is of an order of 2 ms. Thus, a measurement cycle should take at least something like 10 ms, achieving a maximal measurement rate of about 100Hz.

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