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I have a Nexus S and I have specialty RFID writing hardware and passive RFID tags. I can write strings to the RFID tags (and read the strings back using the same hardware) but none of the NFC demo apps on Android I've tried show me the actual string.

What methods would I use to read the actual string byte data from the passive rfid tag? Everything I've looked at just gives me diagnostic information about the tag not the data present on it

The data isn't encrypted to my knowledge, just plain text.

I am not sure if the NDEF standard is usuable on passive RFID tags, the addressing might be different or something. Insight appreciated.

CQM
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  • Is the data stored in NDEF records on the tag? What kind of RFID tag are you using? Do you know what standard it is using? – Ben Ward Oct 05 '11 at 03:28
  • I'm using ISO15693 passive RFID tags. Do I have to use NDEF for an NFC device to read the string data?? I wasn't aware of this limitation (or should I say, feature), let me know what you know! – CQM Oct 05 '11 at 06:14

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For what you are trying to do, you cannot read your tags using NDEF. NDEF is a format for storing data on your tags, not for the process of reading or writing tags. The issue that you are running into is that the communication protocol you are using (ISO 15693, or NfcV) is not used with any of the tag types that support NDEF Records (Type 1-4). The basic demo apps will try to pass data via NDEF, but don't usually have support for transmitting and receiving raw data using the other standards (I believe they would identify other cards by ID number). You would have to write your own app, to connect to a NfcV card and use the transceive(byte[]) command to send custom coded commands to read and write data.

Ben Ward
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    this is helpful, puts me in the right direction http://developer.android.com/reference/android/nfc/tech/NfcV.html – CQM Oct 05 '11 at 23:53
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    Ben, how do I initialize an NfcV object or a Tag object? I can't find any examples on the net showing this, I can't do `new NfcV` or `NfcV nfcMessage = NfcV.get(new Tag());` because either NfcV constructor is not visible or the Tag constructor is not visible..... – CQM Oct 08 '11 at 21:17
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    I would try this: Tag tag = intent.getParcelableExtra(NfcAdapter.EXTRA_TAG); and then NfcV mTag = NfcV.get(tag); You have to get the tag from an intent, and then get a NfcV tag from it – Ben Ward Oct 10 '11 at 21:39
  • can you look at my new question? http://stackoverflow.com/questions/7728976/android-nfc-do-a-null-check-in-oncreate – CQM Oct 11 '11 at 17:32
  • Ben, can Android write to the other NFC/RFID technologies? I know it can write to the main NFC tags, but what about the NfcV that I am using. I'll eventually try it with a byte stream, but I couldn't find anything saying this was possible – CQM Nov 14 '11 at 02:19
  • thank you both. i had a very similar question and it really helped me to learn about all of the NFC/RFID thingy – eladyanai Jul 29 '15 at 17:27