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Setting the password and configuration pages on a Tag

Question asked by Rob Helvestine on Nov 1, 2018

Hello,

In my system I'm trying to setup the password protection on my NTAG213 based Tag. This is done in the four Configuration pages starting from address 0x29, shown below.

 

 

My issue is that the datasheet does not fully explain the state of the Tag while these pages are being written to one at a time. At what point is the Tag password protected? Is it once the AUTH0 byte is set to an addressable page? Or is it when the Access byte PROT and CFGLCK bits are set? 

In my code, I first set the PWD and PACK information on addresses 0x2B and 0x2C. I figure just setting this information does not enable the password protection, and the Tag remains happily in the active state. 

I then set AUTH0 by writing to page address 0x29. I believe, but am not certain, that the Tag is now password protected. What state does the Tag do into at this point? Does it remain in the Active state? Does it require the password to move into the Authenticated state in order to write to 0x2A? Does it need a power on reset (POR)? I've noticed that if I immediately write to 0x2A, while still in the Active state, the data does not get written to the Tag. I usually do a POR and move all the way through to the Authenticated state in order to write to 0x2A. 

 

In other words, is there a way to write to all 4 Configuration pages without having to do a POR, and be in the authenticated state in order to perform reads and writes?

 

Thank you,

Rob  

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