I've never used NFC until today, so I expect i am doing something wrong.

I enabled NFC using the system wide toggle in Settings > Connected Devices > Connection Preferences > NFC.

But when I try and scan an NFC enabled device (Passport, glucose monitor, etc.) nothing happens...

I tried a couple of apps, and had exactly the same result.

It should just work, I expect? Unless it's blocked by a permissions setting somewhere... What am I doing wrong?

Not sure how to debug this one...

Thanks

  • user replied to this.

    From what I know, GrapheneOS shouldn't interfere with NFC tags at all. It does, however, interfere with NFC tap payments (Google Pay thinks it's a very dangerous and unsafe operating system).

    Does the phone vibrate/play a sound when tapping an NFC tag (unmute your phone)?
    If not, it's not even detecting the tag. Try tapping it where the wireless charger is, about in the center of the back glass, below the camera bar.
    If it did give you confirmation (sound/vibration), but still nothing happens, then it doesn't know what to do with that tag - you probably need to install an app, or scan it while the app is open. If nothing still happens, try installing NFC Tools (unfortunately closed-source on Google Play) and scanning the tag from there.

    Are you using a phone case? Try it without. If nothing else it will eliminate a potential problem.

    Yes, it doesn't do anything at all. No sound or vibration. I tried with another phone and it just works.

    No phone case on the phone either.

    Not sure what to do now... I guess it could be a faulty NFC reader... I wonder if there is a way to check if the NFC reader is available, or diagnose it somehow.

    For you I just tried a little experiment.
    I turned on the NFC and approached the phone with a bank card.
    Nothing. Not even a ping
    I downloaded and opened NFC Tools from Play (orange box, phone in middle with N halfway)
    Approached with the card again.
    This time it pinged and read the details easily.
    Therefore, I assume, it doesn't work because no app has been set to deal with such a situation.
    Were you are making a payment at a card reader, it should trigger your payment app if one has been set.
    My phone is a P8 pro inside an "armoured" case, and it worked easily

    By the way, you should be able to scan your cat or dog's implant chip with that app

      grutalno

      Do you have Google play services installed with permissions granted?

        user
        Yes, I think I do. I often see the notification about Sandboxed Google Play services is running. And I can run Google Play and download apps etc...

        Is there some setting that could potentially be blocking NFC though?

        PaulDavis

        Hey, thanks for going to the effort, appreciated.

        I tried that app, it's pretty cool. I was using an NFC reader from F-Droid.

        Unfortunately the result was the same, just nothing.

        I'm specifically trying to read a Continuous Glucose Monitor that is STUCK IN MY ARM, lol.

        Not sure what I'm going to do if I can't get it working.

        I tried a few different NFC chips with NFC tools and none of them worked. I tried with someone else's phone and it just works.

        I found this in the NFC service logs:

        06-13 22:05:33.060 3461 3461 I auditd : avc=type=1400 audit(0.0:825): avc: denied { read } for comm="main" name="u:object_r:build_attestation_prop:s0" dev="tmpfs" ino=111 scontext=u:r:nfc:s0 tcontext=u:object_r:build_attestation_prop:s0 tclass=file permissive=0

        Is that significant? I looks like SELinux blocking NFC from doing something...

        There is a whole bunch of different logs similar to that one, with avc: denied.

        If it's helpful the logs are here: https://rentry.org/q3ffq2w2

        Albeit they are probably using google android, there seems to be a common complaint on reddit matching your issue.
        The solution? Turn the phone off and on again. Nobody has anything better to offer.
        It seems that you can also lose the NFC option if you turn that off and back on later.
        Those commenting seem to have phones from the UK market, as if that should make a difference.

        Maybe you just need to send your arm in for a service

        There are a plethora of different NFC standards. They are mainly based on three different frequencies. Then there are different security levels and different modulation methods such as type A and B. Mobiles usually just work with 13.56 MHz.

        I recommend testing your NFC app with a known NFC tag such as one of the NTAG series. Medical devices and passports do have countermeasures that ensure only qualified devices can access all the features.

        When I read a Swiss passport with NXP TagInfo I get an error "Tag communication was interrupted". I can only read that the passport is an "Electronic identity document". How useful an information!

        I would expect that if you want to communicate with your glucose tracker you need the app from the manufacturer.

        Have you tried the Freestyle Libre app (2 versions) which is for Flash Glucose Monitoring? Perhaps your device needs to handshake with an appropriate bit of software.

        Ok, I got it. Stupid mistake...

        I've been so busy that my phone has never been on charge long enough to get above 90%... so the battery saver feature was on.

        Weird thing is that I checked the battery saver function, as I knew that would disable NFC, and it was not enabled.

        But this morning when I unplugged my phone, there was a notification saying Battery Saver has been disabled, something something your device features are enabled.

        And when I checked NFC by trying to read a tag, it was working.

        Seems a bit counter-intuitive that you can enable and disable NFC without any indication that it's not going to work because Battery Saver is enabled.

        Thanks everyone

        • de0u replied to this.

          grutalno Thanks for reporting back! This information may well be useful to others.