Proxmark3 community

e2020

Member

Registered: 2010-03-05

Posts: 2

if selfbuild: what's the smallest size possible?

hello :-)

I'm interest in a really really small rfid-reader - so my question is:
what's the smallest size possible if one would build an own?

i saw these: http://www.proxmark.org/forum/topic/264 … rk3-setup/
they are really nice! but what's the smallest size possible?

thanks in advance for your help!
oliver

@marauder
thanks - I edited my post :-)

Last edited by e2020 (2010-03-05 19:18:27)

marauder

Member

Registered: 2009-02-10

Posts: 6

Re: if selfbuild: what's the smallest size possible?

Do you mean a RFID reader?

wbahn

Contributor

Registered: 2010-02-03

Posts: 23

Re: if selfbuild: what's the smallest size possible?

That's going to depend a lot on what features you want and also what you mean by "small".

The ProxMark3 is almost exactly the size of a credit card (just slightly smaller in both dimensions), but it has a lot of features -- specifically, it is much more than just a reader: it supports RFID in 125/134kHz and in 13.56MHz; it can program tags, it can communicate with tags (as opposed to just reading a static ID string coming back); it can emulates tags, and it can perform quite a bit of signal processing on the FPGA.

If you only need one type of tag, ID-string read-only capability, and can do all of the processing on the ARM, then you could greatly simplify the circuit. Also, while I haven't checked explicitly, the pads for the resistors and capacitors seemed larger than required for 0603 components -- I had the impression that they might have originally been intended for 0805. Given how many of these components there are, you could gain quite a bit of shrinkage by going to 0402 or even 0201 compnents. You could go smaller, but 0201 is the smallest I have ever done by hand and I'm not sure how easy I would find doing anything smaller. Also, the components are strictly on one side of the board. If you were to go to a six layer board you could probably come close to cutting the dimensions in half (in both directions) by populating both sides, though this makes it thicker (hence, what is meant by "small"?).

Taking all of this into account, my guess is that you could conceivably build a stripped down PM3 on a board that was somewhere between one and two square inches and still have something that could be built without custom parts. That's probably on par with how small you could make a reasonable antenna (for that guess, I'm just going on the sizes I've seen).

Keep in mind, however, that there are cheap RFID reader ICs out there. I have a module, that I got as a "get me started with something" fallback, that I think does just about everything (as a LF reader) producing an RS-232 data stream. The cost was about $25 and it is noticeably under 1" on a side.

Last edited by wbahn (2010-03-09 04:32:12)