I am reading/writing an RFID tag that uses an NTAG213 IC and the Dynamic Lock Bytes are not working as I expected. I have written bytes 0, 1 and 2 of the dynamic lock bytes to the values 0x00, 0x00, 0x3f respectively with the assumption that would render pages 16 through 19 of the memory as read-only. However, I just discovered that I am able to write and modify the memory in at least pages 16 and 17 (I have not tried writing to any of the other pages that I thought were locked).
Is there more to these lock bytes than simply setting the bits that correspond to the pages for which read-only access is desired?
Any information would be greatly appreciated.