Questions on Formatting ST25DV Tags for NDEF

[shahbaz]

For our NFC project, we are developing a mobile application that supports both iOS and Android. We are using React Native along with the react-native-nfc-manager library. Some of the core features include reading and writing raw memory blocks as well as handling different types of NDEF messages.

At the moment, I am working with third-party NFC modules that come preloaded with an NDEF message and a CC file, and that support both NfcV and Ndef technologies. Reading and writing raw data with these modules is straightforward using NfcV transceive on Android and ISO15693Ios sessions on iOS. NDEF messages can also be read and written directly by opening an Ndef technology session.

However, these modules don’t represent factory-fresh tags. To simulate a new tag with empty memory, I clear the tag’s memory using the ST NFC mobile application, which wipes both the CC file and any NDEF messages.

After clearing, the tag only supports NdefFormatable technology. I am unable to format an empty tag back to Ndeftechnology, meaning I cannot open an Ndef session to read or write NDEF messages. The only successful approach I’ve found is to use an NfcV session and manually write the NDEF message to memory blocks.

My questions are:

1. Is there a way to format an empty ST25DV tag back to Ndef technology, or must I always manually write the NDEF message using NfcV transceive? I tried using the format function, but it did not work.

2. Does a new ST25DV tag come preloaded with a CC file?

3. Is a new ST25DV tag always set to NdefFormatable technology by default?

[France Berthelot]

Hello

1 :

ST25DV tags are NFC Type 5 (ISO 15693) tags.

Android’s Ndef technology requires the tag to have a valid NDEF message and the correct NDEF TLV structure.

When a tag is “empty” (factory state), it may not have the NDEF TLV structure, so Android won’t recognize it as Ndef.

There is no automatic Android API or built-in method to format an empty ST25DV tag to NDEF.

Use NfcV.transceive() to write the following:

TLV for NDEF:

• Type: 0x03 (NDEF Message TLV)
• Length: Length of your NDEF message
• Value: The NDEF message bytes

TLV Terminator:

• Type: 0xFE

 

2 : No, cf Datasheet.

 

 

3: No, need to go further….

NdefFormatable is an Android NFC technology class that represents NFC tags which do not currently contain an NDEF message, but can be formatted to support NDEF.

I am pretty sure that :

• Type 5/ISO 15693 (ex : ST25DV) : Android do not provide NdefFormatable, and you need to manually write the NDEF message to memory blocks using NfcV….

From my knowledge, the main process in Android is:

• Is it a supported type (usually Type 2, some Type 1/4)
• Is it blank or raw (not already NDEF)
• Is it writable
• Does It have enough space for NDEF

 

Hope this clarify.

Regards, FB