NTAG213F/216F
NXP Semiconductors
NFC Forum T2T IC with 144/888 bytes user memory and field detection
10.7 PWD_AUTH
A protected memory area can be accessed only after a successful password verification
using the PWD_AUTH command. The AUTH0 configuration byte defines the protected
area. It specifies the first page that the password mechanism protects. The level of
protection can be configured using the PROT bit either for write protection or read/write
protection. The PWD_AUTH command takes the password as parameter and, if
successful, returns the password authentication acknowledge, PACK. By setting the
AUTHLIM configuration bits to a value larger than 000b, the number of unsuccessful
password verifications can be limited. Each unsuccessful authentication is then counted in
a counter featuring anti-tearing support. After reaching the limit of unsuccessful attempts,
the memory access specified in PROT, is no longer possible. The PWD_AUTH command
is shown in Figure 21 and Table 37.
Table 38 shows the required timing.
NFC device
Cmd
Pwd
CRC
NTAG ,,ACK''
PACK
T
T
ACK
NAK
623 µs
274 µs
NTAG ,,NAK''
NAK
57 µs
T
TimeOut
Time out
aaa-006993
Fig 21. PWD_AUTH command
Table 37. PWD_AUTH command
Name
Cmd
Pwd
Code
Description
Length
1 byte
1Bh
password authentication
password
-
4 bytes
2 bytes
CRC
PACK
NAK
-
CRC according to Ref. 1
-
password authentication acknowledge 2 bytes
see Table 21
see Section 9.3
4-bit
Table 38. PWD_AUTH timing
These times exclude the end of communication of the NFC device.
TACK/NAK min
TACK/NAK max
TTimeOut
PWD_AUTH
n=9[1]
TTimeOut
5 ms
[1] Refer to Section 9.2 “Timings”.
Remark: It is strongly recommended to change the password from its delivery state at tag
issuing and set the AUTH0 value to the PWD page.
NTAG213F_216F
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© NXP B.V. 2013. All rights reserved.
Product data sheet
COMPANY PUBLIC
Rev. 3.1 — 28 August 2013
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