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Issue with RFID module — Parallax Forums

Issue with RFID module

dspeerdspeer Posts: 7
edited 2006-04-23 05:46 in BASIC Stamp
I just got my RFI reader and some tags and got them to work with a BS2 - but there is an issue that I don't understand and can't seem to fix.

I am running a program that I derived from the manual. After hooking the module up and swiping the tag a few times, the voltage at the module's pins begins fluctuating to a degree that makes the LED on the module itself flicker red/green. At this point the readable distance goes way down. As soon as a tag is read, everything seems fine for about 2-3 seconds, until it starts again.

I have tried this directly on a homework board (battery) as well as a breadboard connected to an activity board (9V power supply) - both times with the exact same results.

I also went back to the original program from the manual - same thing.

Do I have a bad module, am I doing something wrong?

Any help would be appreciated.

D.

Comments

  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2006-04-22 05:39
    It's possible, depending on which revision H/W Board you have that it can't supply enough current to run the module.· How is it connected for power and which revision H/W Board do you have?

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    Chris Savage
    Parallax Tech Support
    csavage@parallax.com
  • dspeerdspeer Posts: 7
    edited 2006-04-22 06:10
    Revision B for the homework board, baught 2 weeks ago at Radio Shack.

    Same issue on the (older) Activity Board.
  • ForrestForrest Posts: 1,341
    edited 2006-04-22 09:05
    The RFID reader requires 90 mA when active and the Rev B Homework board can only supply 50 mA. I don't know what the specs are for the Acitivity board.

    The solution is fairly simple - at 7805 or a 2940-5 regulator with appropriate input and output capacitors (see data sheet) connected to a 7.5-9V battery will give you 300 mA of power - enough to run the RFID reader. Just be sure and tie the grounds together.
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2006-04-23 05:46
    Yes, that could definately be your problem, which was why I asked which revision your H/W Board was.· Try using a separate 5V power supply to power the RFID Reader, but make sure you have a common ground.

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    Chris Savage
    Parallax Tech Support
    csavage@parallax.com
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