125 kHz USB RFID

Question

After some experimentation with a MFRC-522 13.56 MHz RC522 RFID Reader I decided to try 125 kHz tags.

I bought a 125 kHz USB RFID Contactless Proximity Sensor Smart ID Card Reader EM4100 which comes with a USB interface, but absolutely no documentation (that I could find) although every second vendor on eBay seems to sell them.

The Pi sees the vendor as AuthenTec, Inc and mounts as character mode device on \dev\hidraw3.

I can cat \dev\hidraw3 and see it is obviously reading the card and outputting something that looks like the card number.

Can anyone help with software or documentation?

out of curiosity: what setup did you use for your 13.56 reader and did you get it to work? — Wim Ombelets, Apr 09 '16 at 07:47
@WimOmbelets I used the SPI interface on an Arduino for the RC522 — Milliways, Apr 09 '16 at 08:42

score 1 · Answer 1 · answered Apr 09 '16 at 11:06

I just had a look at some Amazon reviews (hopefully of the item you have).

The reviews suggest it does not have a full SDK. It just acts as a keyboard and prints out the card number (plus carriage return).

One reviewer noted that the DIP switches change the data format as follows.

So I have a card with the UID 4B32EcDE (32bit Dec 3740021323) in the format I want, the dip switches allowed my to read the card as the following values:

0000: 3740021323
0001: 00deec324b
0010: 15479371
0011: b423ceed
0100: 0015479371
0101: ec324b
0110: 40021323
0111: 3740021323
1000: 23612875
1001: 374002132323612875
1010: 1261628638
1011: 3740021323
1100: deec324b
1101: 3740021323
1110: 12875
1111: 5706812875

score 0 · Accepted Answer · answered Apr 10 '16 at 07:34

I think I had overcomplicated the problem.

In the end I just used the output of the Card Reader as a keyboard. The card numbers appear (without the garbage) on input.

I obviously need to learn more about character mode devices and how to select only the one I want - not the actual keyboard.

125 kHz USB RFID

2 Answers2