2263320_en-US

[#1]

Unable to remove write protection on NTAG213 after enabling password protection (AUTH0/ACCESS)

Hello NXP Team,

I am working with NTAG213 tags using the PN7160 NFC controller and the NXP Linux nfcDemoApp.

What I have done successfully:

1. I modified the nfcDemoApp (main.c) to enable write-only password protection on NTAG213 by configuring:

   • PWD

   • PACK

   • AUTH0

   • ACCESS (PROT = 0)

2. The write protection works correctly:

   • Mobile NFC apps cannot write anymore

   • Writing is possible only after sending PWD_AUTH from my application

3. • Reset AUTH0 to 0xFF

   • Clear ACCESS

   • Re-write configuration pages

     I also enabled write protection on another NTAG213 using NXP NFC TagInfo / NFC Tools app, and that also worked as expected.

     Problem I am facing:

     Now I am unable to remove the write protection in both cases:

     • Using my own code (nfcDemoApp)

     • Using NXP NFC Tools / TagWriter mobile apps

     Even after authenticating with the correct password (PWD_AUTH), attempts to: are failing .

   My understanding:

   From the NTAG213 datasheet, I understand:

   • PWD_AUTH should allow writing to protected pages during the RF session

   • After authentication, it should be possible to modify AUTH0 and ACCESS

   • NTAG213 does not have permanent lock bits for password protection (unlike lock bytes)

   However, in practice, I am unable to revert the tag back to an unprotected state.

   Questions:

   1. Is it officially supported to remove or disable password-based write protection on NTAG213 after it has been enabled?

   2. Are AUTH0 and ACCESS pages writable after successful PWD_AUTH, or are they permanently protected once set?

   3. Is there a recommended sequence to restore NTAG213 to a writable (unprotected) state?

   4. Can NXP NFC Tools / TagWriter remove password protection on NTAG213, or is custom raw command handling required?

   5. Is full reset (RF session reset / power cycle) required after authentication to modify configuration pages?

   Any guidance or clarification from the NXP team would be very helpful.

   Thank you for your support.

   Best regards,
   Niranjan

Re: Unable to remove write protection on NTAG213 after enabling password protection (AUTH0/ACCESS)

I use the RFIDDiscover. It is able to change the settings in configuration page to remove the protection.