Read range of Arduino compatible NFC readers?

Hey all,

I’m looking to enable a couple of new projects, but the first is just unlocking my PC. I’m intrigued with the possibility of mounting an NFC reader under the table. I’m planning on pairing whatever reader I select with a small Sparkfun Pro Micro (Arduino) just because I have one on hand. The Adafruit shield seems to be a popular choice, and I doubt it has to be mounted as a shield as long as the right pins are used. It seems to be a better option than the commonly used Elechouse because it advertises a 10cm read range which might make sense given the large size of the board (and bigger antenna size).

That said:
What are YOU using for an NFC reader with YOUR Arduino project?
What’s the read range with your xNT?


Yes we’ve heard good things about the Adafruit NFC shield, however you should understand you will not be getting that advertised range. Everyone wants to know “what’s the range” like it’s a gun shooting a bullet… a one-way transmission, which RFID and NFC are not. A truly honest answer to that question is: it depends on how well the reader and tag antenna couple with each other. So, while their shield may get “10cm” with an ISO standard card size tag, it will not have the same performance with our xNT or even our flexNT.

I personally use an ACR122U for computer login. There are two software packages that work well for Windows login:

If you’re wanting to use the xNT or flexNT for PC login, then I’d try the first option. It’s free and works well enough. The second option is not free, and possibly a bit less user friendly, but it will become useful in the near future with the release of VivoKey.


Thanks Amal! Yeah, I didn’t really expect to get the advertised range vs a full size tag. I figured if people reported what they were using a pattern would emerge - like which ones seemed to work the best with this form factor tag.

Thanks for turning me on to those login projects! They both look promising, thought the lack of support for a Windows domain account is disappointing. I guess that’s the one advantage of the Arduino / NFC shield approach. You just send keypresses! I’ll probably mess around with these projects for my home PC.

Anyone else using a different reader that they like?

If you are looking for domain support, you might try using the built in smartcard framework for windows login. You might be able to use the xNT with it, or maybe not. If not, you should try working with the NFC Connector linked above along with this reg file;

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Cryptography\Calais\SmartCards\Dangerous Things xNT]
“Crypto Provider”=“MySmartLogon NFC CSP”

Copy everything between the === lines and put into a xNT.reg file, then run the file to import the changes. That should ensure the xNT is seen as a “smart card” by Windows and it will also ask the NFC Connector to process the “card”. I’ve not attempted this myself, but it may work for domain accounts. If not, then I’m sure the full EIDAuthenticate product will work with domain accounts just fine.

We are looking forward to the release of VivoKey, since it will work with the Windows smartcard framework directly.

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Hey Amal, this is pretty awesome. I’ve gotten my ACR122U working with ISLOG, and I can unlock a previous logon session. However, I have to enroll the tag on login the first time - every time. The auto-enrollment complains about “cannot store data on card” when it tries to write to my xNT. Now, I can write any number of payloads with NXP TagWriter. I’m guessing ISLOG wants to completely unlock the tag, but I’m wondering what your experience has been.

I’ve also opened an “Issue” against the ISLOG project to see if they have some insight.

hmm ok, it sounds like ISLOG is yet another software package that is not properly parsing lock bytes or the AUTH0 byte… someone’s being lazy. I’ll ping them…


I’m referring them to this thread, because it explains what Dangerous NFC does, but figured it’d be a good one to post here as well.

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Heh, yep, the other thread I started, good to tie them together. When I opened my issue on the ISLOG project I referred to it as well.

Here’s the open issue. No idea if they use that list or monitor them though…

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This is what I got back from ISLOG

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Thanks for the follow-up Amal! I got something very similar from Maxime as well thanking me for opening the issue against the project for tracking purposes. I’ll keep my fingers crossed that they update, and in the meantime I’m thinking of experimenting with the community editions of EIDAuthenticate and NFC Connector to see how they do too.

Hey there.
Does anyone knows if there´s a working solution for this problem out there? I´ve tried it now with ISLOG, but the data will not be stored. The other two suggestions are not working any longer with Win10 :frowning:
Or perhaps a similar app that works well with a xNT?


ISLOG doesn’t store the key on my implant to allow for login authentication, but it still works for session authentication. The first time I log in I have to scan and enter the username and password. It’ll error out because it can’t store on my implant. If I lock my screen and come back then it will work to unlock the current session. Given that I don’t reboot my computer more than once a week this works pretty well.

Checking on the TODO items list on ISLOG, it doesn’t look like this issue has been addressed yet.