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I am working on an Android 4.0 application using NFC on my Samsung Nexus S and I would need to modify some advance settings: the time of the NFC field pulse especially.

I developed my first applications and they work fine with most of the NFC tags but I need to use some special tags which need much more time to make calculations and the NFC field pulse is too short: my tag will consistently be stopped (power cut down by the phone every ~0.1 or 0.05 sec).

I am very new in Android development but I have heard about the Native Development Kit (NDK) which provides "more advanced" tools to deal with low-level operations. I also heard it was often mystified by Android programmers as the magic solution for any problem.

Do you think NDK provides more flexibility regarding NFC programming? Could it help me with my task?

I thank you in advance, Regards

GChabot
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2 Answers2

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Do you think NDK provides more flexibility regarding NFC programming?

AFAIK, the NDK has no access to NFC at all, except by means of calling back into Java code.

CommonsWare
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Your tag problem may be due to the fact that the NFC stack checks for an NFC Forum NDEF message (Type 4 Tag in this case, I am guessing) and the tag takes too long to answer (it is likely sending Waiting Time Extension requests). The connection to the tag is then simply broken off and the NFC stack continues polling for new tags. You cannot influence this behaviour without changing and recompiling parts of the Android OS, so use of the NDK will, in all likelihood, not help in solving your problem.

NFC guy
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  • Yes, this is exactly what happens. So you think my problem is desperate? Unless I recompile parts of the Android OS (i.e. create a custom ROM?) I mean, but if I do so, do you believe it would be possible to force the phone to wait longer? Because might it not be a parameter set in the hardware chip? – GChabot Mar 25 '12 at 17:59
  • I don't think this is a NFC hardware issue (although I cannot completely exclude it), but likely a software timer. However, finding out where and how to change this, may be a difficult problem. – NFC guy Mar 25 '12 at 19:47
  • Ok, I believe it is too bad that Android developers didn't give possibility to access these settings because, as it is most likely software, it would be very easy for us to allow it. And without it, a whole set of tags just can't be used. Unless it is part of the NFC Forum specifications that NFC tags **must** reply within 0.xx seconds. – GChabot Mar 26 '12 at 08:30
  • NFC Forum specs do not require this. I think this is a usability issue: Android wants to decide whether the tag contains NDEF within a certain amount of time. IMO, it would be better if Android in this case would simply report no NDEF and still connect to the tag and make it available to apps. – NFC guy Apr 02 '12 at 11:50
  • @NFCguy Please help me in this http://stackoverflow.com/questions/10733723/launching-nfc-when-screen-is-locked-in-android/10734069#comment14535285_10734069 – Venky Jun 19 '12 at 10:35