问题
I'm trying to authenticate a Mifare Ultralight C (ISO/IEC 14443-2 and 14443-3 type A compatible) tag.
I send the authentication command with the MifareUltralight.transceive() function provided in Android. I have also checked NfcA.transceive() (IsoDep seems not to be compatible with this kind of tag because this object is for dealing with ISO/IEC 14443-4 tags and that's why I don't use IsoDep.transceive()).
So, when I first send the authentication request command the tag answers the transceive() with AFxxxx..... where I process the tag answer and then I send another transceive() with the response to that answer but... just before sending the transceive() the tag is connected, when it's sent I get a "tag was lost" warning and a "transceive failed".
Also, if I try it with NfcA the same problem happens.
Finally, if I try to send one authentication command after the first one response I get also a "Tag was lost" warning with the transceive fail.
So my question is:
Why does the NFC tag get lost when I send the second transceive()?<<
(It doesn't seem to be a timeout problem because just before sending the second transceive() the connection is open with the tag) I made all the stuff in a different Thread from the UI one.
Thanks in advance!
回答1:
Your approach seems to be correct. However, the tag's behaviour indicates that your response to the tag's answer was incorrect. In that case, the tag refuses to answer. From the phone's point of view this is indistinguishable from the tag having disappeared, so you get a TagLostException.
来源：https://stackoverflow.com/questions/9670077/mifare-ultralight-c-authentication-in-android-2-3-6