Posted on May 22, 2014 at 18:40Dear Ten,
In NFC Forum T4 Tag Operation specification, 0x80 value is specified as follows, for Read and Write access conditions:
- 80h to FEh indicate a limited read access granted; access is granted based on proprietary methods.
- 80h to FEh indicate a limited write access granted; access is granted based on proprietary methods.
This means that any chip manufacturer can use 80h to FEh values, if he wants to implement its own method for limiting Read/Write access.
There’s no additional specification, that will reserve specific values to specific manufacturer.
This means that any manufacturer can use 0x80 for its own method.
In other words, STMicroelectronics chose this value, but any other chip manufacturer may also use it.
If you face such value, you need to identify the chip manufacturer, to apply suitable proprietary method.
To discriminate STMicroelectronics chips, you can use the Manufacturer ID (0x02) of the tag UID (as returned at the end of anti-collision process).
Hope this clarifies this point for you.
Best regards,
