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Decode 134.2 kHz FDXB RFID — Parallax Forums

Decode 134.2 kHz FDXB RFID

phishguyphishguy Posts: 36
edited 2010-06-09 23:15 in Propeller 1
I was wondering if anyone has ever used a propeller to decode 134.2 kHz FDXB RFID tags. The tags use a biphase encoding of rf/32, where a logic 1 is 2 transitions and a logic 0 is 2 transitions. It is a 128 bit tag structure. There is further encoding withing the data of a header, stuffing bits, tag number, crc, and trailer bits. However, I am only interested in getting the bitstream right now and I can take care of the rest of the decoding. I also don't need any reader circuitry as I already have the driver, filter, and comparator circuitry. I have seen an example for an RFID reader using FSK manchester encoding. However, I couldn't figure out how to modify that code for biphase. Does anyone have any ideas, guidance, or information on biphase decoding?
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Comments

  • MicrocontrolledMicrocontrolled Posts: 2,461
    edited 2010-06-09 23:15
    The current Parallax RFID reader is unable to read these types of cards. You would have to wind your own coil and use the prop's internal counters to do something like this. There is something about this in the OBEX. You should check it out.

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