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#1 2009-11-30 23:21:50

jiri
Member
Registered: 2009-11-30
Posts: 2

EM4102 tag decoding

Hi, recently I obtained PM3 and tried reading LF tag with EM4102. Only binary digits were printed
when following the instructions, which is rather inconvenient. Therefore I added some code to the winsrc/command.cpp
file to decode the data according to the EM4102 datasheet, checking the parity bits and printing the net result in hex.
Since I am new to this project, I do not know, whom/where to send patches etc. in order to contribute to the source...
Can you please advice me?
Jiri

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#2 2009-12-04 14:12:42

edo512
Contributor
Registered: 2008-10-07
Posts: 103

Re: EM4102 tag decoding

Thanks for your input. Have you tried the following command:

em410xread

Reads the ID from an EM410x tag (the plot should contain the raw tag). Clock is optional, usually has a value of 64.

Example :

> loread
> losamples 2000
> em410xread
Auto-detected clock rate: 64
EM410x Tag ID: 1a0041375d

   Doesn't it do what you want? You can submit your patch in this thread if you want (please refer to other threads where people have already submitted patches) so that we can take a look!

Ed

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#3 2009-12-04 14:31:02

jiri
Member
Registered: 2009-11-30
Posts: 2

Re: EM4102 tag decoding

Thanks, in the meantime I found this command in the reference manual and it works. Maybe it should be mentioned
in the tutorial, too.

Jiri



edo512 wrote:

Thanks for your input. Have you tried the following command:


em410xread

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#4 2010-03-07 02:51:03

toffe
Member
Registered: 2010-03-07
Posts: 13

Re: EM4102 tag decoding

I recently aquired a proxmark3 and have been fiddling with some LF decoding. However, for a small (implanted) 12x2mm glass tag, I have troubles getting the prox software to properly decode the data.

Plot
Raw data produced with the save command

First of all, it seems I have a DC offset, so I tried hpf, which nicely centered the wave along the x axis. But mandemod/em410xread still failed decoding with no error output.

Any ideas of what could be wrong? I've at least managed to get decent LF antenna tuning:

# LF antenna: 35.05 V @   125.00 kHz
# LF antenna: 33.70 V @   134.00 kHz
# LF optimal: 40.42 V @   126.32 kHz

Thanks for any pointers,

Toffe
Proxmark newbie

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