Propeller RFID Reader

DogP

Hey,

Now that I've got an RFID card from UPENE, I'm trying to figure out what to do with it... I saw the Parallax RFID reader on the back my Nuts & Volts magazine, and I remember the coil wrapping I did to make the Propeller an inductive sensor, and I was thinking... could the Propeller be an RFID reader? It looks like it needs to oscillate at 125KHz, which the prop can do, and I assume sense some changes to be able to demodulate the signal (which I also assume it could do). Has anyone tried this, or have any ideas how it could be done? Or, I guess, does anyone have any good links on how the tags work?

Oh, and how about emulating a tag... I assume that would be possible as well?

Thanks,
DogP

Harrison.

There is a software based RFID reader for the Propeller in the obex obex.parallax.com/objects/374/. It works very well, and even auto adjusts the tank frequency to try to match your coil/cap configuration.

For the coil I just purchased some Radioshack magnet wire and wrapped it around a CD spool case. I did some rough air coil calculations to get the ballpark number of turns required and then removed turns until I got the highest peak voltage across the LC tank (a scope is very handy for this).

DogP

Wow... very cool! How did I not see this before? I'll have to throw one of those together. BTW, I really don't know much about these, but is there any reason it couldn't be modified to do the high freq RFIDs? Of course I should start simple w/ the low freq ones (and read up on how they work), but I'm just curious.

Thanks,
DogP

Mike Green

The Propeller isn't fast enough to do high freq RFIDs.