[Hackrf-dev] Help with NFC decoding.

[evilsocket]

> I think this is a great goal, but have you considered using GNU Radio
> to confirm that it works and then rewrite it in C/C++ piece by piece?

Yep but in that case would be copying, not understanding, wouldn't it? :D

> Have you looked at the waveform to see if you can identify where the
> data is being transmitted?

Yep, I'm on the right frequency and it's clearly ASK.

> I think you're on the right track.

Great! :D

> It probably depends on what is being transferred.  A good place to
> start would be these specs:
> http://members.nfc-forum.org/specs/spec_list/

Thanks so much :)


2015-04-17 21:48 GMT+03:00 Dominic Spill <dominicgs at gmail.com>:

> On 17 April 2015 at 15:25, evilsocket <evilsocket at gmail.com> wrote:
> > Hi everyone, I'm trying to decode NFC-A ( 13.56Mhz ) data from the HackRF
> > using C/C++ code instead of GNU Radio, mostly because I want to
> understand
> > the logic of demodulation and decoding itself instead of using pre made
> > tools.
>
> I think this is a great goal, but have you considered using GNU Radio
> to confirm that it works and then rewrite it in C/C++ piece by piece?
>
> > As far as I read on the web, NFC uses ASK modulation, so what I'm
> currently
> > doing on the rx callback is taking each IQ, computing amplitude,
> > thresholding it to get a 1 or 0 bit, appending each bit to a bit stream
> and
> > print the hex value every 8 bits, you can see the code here:
>
> Have you looked at the waveform to see if you can identify where the
> data is being transmitted?
>
> > I have two questions:
> >
> > 1. Am I on the right track or am I doing everything wrong? :)
>
> I think you're on the right track.
>
> > 2. If what I'm doing is correct, could someone point me to the right
> > documentation on how to decode those hex streams I get?
>
> It probably depends on what is being transferred.  A good place to
> start would be these specs:
> http://members.nfc-forum.org/specs/spec_list/
>



-- 



_________________________
Simone '*evilsocket*' Margaritelli
http://www.evilsocket.net/  <http://www.evilsocket.net/>
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