How do I unlock my password and reset it to its default value?

[d__jin]

Hello.

I am developing an Android application that reads/writes/deletes tags with passwords using Taplinx SDK.
Of course, the function to delete tag data requires password authentication.

However, when deleting tag data, I confirmed that the tag does not return to its initial state, that is, the state when the tag was purchased.
(Here, "state" includes all values ​​in the tag. I don't know what to call it.)

Please check the attached *.txt files.
(This is the content of the tag scanned using the "TagInfo" application.)
The differences (problems) are as follows:
1. Ndef type has been changed to NdefFormatable type.
2. Looking at the memory, it seems that the password setting part is still masked, so it seems that the password release (i.e. initialization) failed.

I wrote the logic to delete the tag in the application as follows.
1. nTag.reader.connect()
2. Attempt tag password authentication (using authenticatePwd())
3. If tag password authentication is successful, disable the password (pass 255 to the second parameter of enablePasswordProtection())
4. Delete the data written to the tag (clear())
5. nTag.reader.close()

I don't know what part of my code is wrong and what action should I add.
If you don't mind, could you help me?

[KaiLi]

Hello @d__jin 

Deleting data does not return the tag to its factory setting, the original state at the time of purchase. And there is no command to return the TAG to the factory setting.

[ukcas]

Hello d__jin,

1. On default NTAG 216, NDEF content contains "empty" NDEF message. Your "programmed" one, doesn't contain it anymore. That's why Android reports it as NDEF Formattable.

[04] . 03 00 FE 00 |....|

vs.

[04] . 00 00 00 00 |....|

2. Your app changes Page 3 by accident as well.

3. Use setStartPageAddressForPwdAuth() to set AUTH0 byte. But I can see that it was not changed from FFh.

Best regards,

TapLinx team

[d__jin]

1. Why does my app change Page 3? Am I doing something wrong? If so, please let me know...
I am using NTag 213 and 216 together and I need to recognize the difference between my tag and other types of tags, so I am using INTag210 interface instead of INTag213215216 interface. According to your answer, I need to use setStartPageAddressForPwdAuth() and for that I need to use INTag213215216?

2. What do you mean when you say that there is no change in FFh?
- Step 1: The initial tag's default value was FFh (04-4E-...-scan.txt).
- Step 2: When I wrote data to the tag, I added a password and so this value changed.
- Step 3: After clearing the data of the tag, I initialized the AUTH0 settings using enablePasswordProtection() (as I mentioned in the first question) (04-2A-...-scan.txt).
What I'm wondering here is why, after going through these three steps, the AUTH0 settings went back to the initial state, but the PWD0~PWD3 and PACK0~PACK1 parts still remained in a masked state.

[ukcas]

Hello d__jin,

1. Please use interface suitable for the product. Else, you may not have all functionalities. Yes, use setStartPageAddressForPwdAuth(). We don't know what your app is doing, maybe you can share some lines of code, or check all writing APIs in your code (that are not using by accident some empty variables for writing to EEPROM). Generally Page3 is one-time programmable. You can only increase the values.

2. As stated in datasheet, PWD and PACK values remain masked. Otherwise, they would be publicly readable.

If above doesn't help, use https://www.nxp.com/support/support:SUPPORTHOME.

There you can provide your business case and open a support ticket.

Best regards,

TapLinx team