Nfc service ocassionaly stops working upon receiving error during card reading

[Mi Vr]

Hi

Im working on Inspection application which reads MifareUL and MifareClssic cards.
Issue im having is that occasionaly NFC service stops working and taping card does nothing after this point (no new events are received).
After this, it is required to disable and enable NFC service again in order to make NFC work.
Device im using is Bluebird EF501. It runs Android 7.1.2.

Reader is enabled like this:
`
val flags = NfcAdapter.FLAG_READER_NFC_A or NfcAdapter.FLAG_READER_NFC_B or
NfcAdapter.FLAG_READER_NFC_F or NfcAdapter.FLAG_READER_NFC_V or
NfcAdapter.FLAG_READER_SKIP_NDEF_CHECK

try {
nxpNfcInstance.enableReaderMode(1000, {
handleTag(it)
}, flags)
} catch (e: Exception) {
Timber.e(e, "Failed to enable reader mode!")
}
`

after decoding what kind of media it is and obtaining ICard object card data are read like this:
`
return withContext(Dispatchers.IO) {
try {
classic.reader.connect()
classic.reader.timeout = CARD_READ_TIMEOUT

val sectorList = IntRange(0, CLASSIC_SECTOR_COUNT - 1)
.asSequence()
.onEach { s -> authenticateSector(s, classic) }
.map { s ->
readBlocksFromSector(s, classic).let { blocks -> ... }
}
.toList()

MifareClassicData(sector = sectorList, uid = uid)
} finally {
classic.reader.close()
}
}

private fun readBlocksFromSector(sector: Int, classic: IMFClassic): Array {
val startBlock = classic.sectorToBlock(sector)
return Array(3) { index ->
classic.readBlock(startBlock + index)
}
}
`

threading is like this:
[Binder thread]
event is sent media processing component
[Main thread]
decoded media type from tag
obtained ICard object
[Dispatchers.IO thread]
reading of card data
[Main thread]
data processed


Do you have any experience with such issues?
Idont know what im doning wrong, what can cause this issue and it is starting to be quit problem.
Also on other device it seems to not happening but im not sure if this is case.

Thansk for helpnig
Michal

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[TapLinx Support]

Hi Michal,

The MIFARE Ultralight and the MIFARE Classic uses ISO/IEC 14443-3 protocol (the “-3” is important). This means, if an error occurs or an invalid key was used, the card goes into internal HALT state and terminate any communication. But this should not shutdown the whole NFC communication on your device! Here you must remove the card from reader (this will reset the card) and put into the field again.

For me it seems that this is an issue in the middleware. Can you check your software on a different device (a different manufacturer)? If both devices behaves different you can identify this as firmware issue. As Android developer you should test your software on so many different devices as possible to prevent device specific issues.

The TapLinx team

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