Operating HB100 backpack with Arduino Due

Question

I need to connect a speed sensor module with an Arduino Due and calculate the speed of an approaching object.

the sensor is: http://www.limpkin.fr/index.php?post/2013/08/09/Making-the-electronics-for-a-%247-USD-doppler-motion-sensor

The sensor already output a signal that its' frequency represents the speed of the object.

I would really appreciate any help understating how can it be connected and operated by the Arduino without burning it, and how can I sample its output?

If more details are needed I'll be happy to supply.

Thanks.The module's connectors

• sachleen: This looks useful: tushev.org/articles/arduino/item/…

Answer 1

The articles and tutorials I've read on the subject say that the HB100 module produces a very weak signal which needs to be amplified before your Arduino can read it. They recommend building an op amp. This post on the Arduino forums, for example: http://forum.arduino.cc/index.php?topic=61989.0

BUT looking at your picture and linked article, I find that your device already includes the signal amplification and filtering you need in the backpack board. I found the store page for this module, which has a more noob-friendly explanation. From what I gather:

• VCC: provide the module with a 5v supply.
• VOUT: analog reading of the amount of return signal being received. My guess is you could use this with analogRead() to get a rough estimate of the size or distance of the object being read. If you want only the speed reading, you don't need this pin.
• FOUT: digital output of the speed that the sensor is reading. Thanks to @sachleen's link, you can use either pulseIn() or FreqCounter library to measure the frequency and then convert it to a MPH or KPH speed.
• GND - ground, aka common, aka -.

So connect VCC to 5v, GND to ground, and FOUT to an input pin on your Arduino. If you use pulseIn(), frequency f = 1 / t, t being the return value from pulseIn(). If you use the FreqCounter library, it no doubt has documentation on its usage.