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PIR Motion Sensor pinout

  1. Mar 4, 2012 #1
    Hi all,

    I am trying to connect a Parallax PIR motion sensor to a mini-usb cable.

    The PIR sensor has three pins: GND (negative), VCC (positive) and OUT.
    The USB cable has four connections: GND, VCC and the DATA (+ and -).

    I am able to power up the sensor and see a voltage spike when motion is detected. However, I am unable to do anything with the OUT pin. I tried to connect the DATA (-) and then the DATA (+), but my system does not see anything using SnoopyPro. When I figure this out, I would like the voltage from the OUT pin to trigger a system response; perhaps a custom program to monitor this.

    Any ideas? Thanks in advance.
  2. jcsd
  3. Mar 5, 2012 #2
    This is similar to plugging an analog microphone into your ethernet port and thinking you will be able to record sound that way.

    USB is more than just a digital signal. It has a rather complicated protocol that must be used. Your operating system's driver is trying to talk on USB to a single bit output, they are just not compatible. Also, you cannot drive just DATA+ or DATA-, they must be differentially signaled together.

    You basically will need a "middle man" device that can convert the single bit output into something meaningful on USB that your computer can understand. They make microcontrollers with USB peripherals that have USB drivers to use those peripherals, and you could program the microcontroller to read the bit and send its status over USB. Other than that, you probably have to scrap the idea of using USB.
  4. Mar 6, 2012 #3
    Thanks for your response. I have an Arduino board with a microprocessor that I was looking to avoid using, but I was told that I can just program the microprocessor and adapt it to a breadboard for testing. I have a bit of learning to do. Thanks again.
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