8 bytes Capability Container (CC) instead of 4 when adding NDEF record to ST NFC tags?

[chai2145]

Hello,

I’m working with an ST NFC tag (e.g., ST25DV) and noticed that when I add an NDEF record using the ST25 mobile apps, the system automatically adds a 4-byte Capability Container (CC) to the NDEF message record.

My question is:
Is there a way to append or extend the CC to 8 bytes instead of the default 4 bytes when adding an NDEF record?

[France Berthelot]

Hello

DV is a type5 Tag

Type 5 tags are based on the ISO/IEC 15693 standard (also called NFC-V or Vicinity)

The CC file is a mandatory data structure in NFC Forum-compliant tags.
It describes the tag’s memory layout, access conditions, and supported features

The CC file is typically 4 bytes (can be longer for extended features)

The CC (Capability Container) file on NFC Forum Type 5 tags is typically 4 bytes, but it can be longer in certain cases, especially when the tag supports advanced features or extended memory.

• Extended Memory Support (More Than 2040 Bytes)
• If the tag has more than 2040 bytes (e.g., 4 KB, 8 KB, or more), the CC file must be 8 bytes to encode the larger memory size and additional features

How Is the Length Determined?

• If the tag’s memory is ≤ 2040 bytes:
  The CC file is 4 bytes.
• If the tag’s memory is > 2040 bytes:
  The CC file is 8 bytes (or more, if required by features).

I do not know on which Tag Memory size you work on, but check memory size, this will explain CC file size.

CC file do not extend to be 4 or 8 bytes long, according to NDEF records stored dynamically!

You define first in CC file the size allowed to the NDEF part, after that according to previous, you can write up to max size with records.

The application rewrites the CC file, if memory doesn’t contain one, according to Tag memory size.

To answer to the Question : No.

To define a CC file, yes, you can use the Memory content menu, and write manually bytes. Not recommended!

Hoppe this clarify.

Cheers,FB