AT88SC0808C Ver la hoja de datos (PDF) - Atmel Corporation
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AT88SC0808C Datasheet PDF : 18 Pages
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AT88SC0808C
Figure 12. Write Lock Example
Address
$080
$0
11011001
$1
xxxx xxxx
locked
$2
xxxx xxxx
locked
$3
xxxx xxxx
$4
xxxx xxxx
$5
xxxx xxxx
locked
$6
xxxx xxxx
$7
xxxx xxxx
The write lock byte may also be locked by writing its least significant (rightmost) bit to
“0”. Moreover, when write lock mode is activated, the write lock byte can only be pro-
grammed – that is, bits written to “0” cannot return to “1”.
In the write lock configuration, only one byte can be written at a time. Even if several
bytes are received, only the first byte will be taken into account by the device.
Password Verification
Passwords may be used to protect read and/or write access of any user zone. When a
valid password is presented, it is memorized and active until power is turned off, unless
a new password is presented or RST becomes active. There are eight password sets
that may be used to protect any user zone. Only one password is active at a time, but
write passwords give read access also.
Authentication Protocol
The access to a user zone may be protected by an authentication protocol. Any one of
four keys may be selected to use with a user zone.
The authentication success is memorized and active as long as the chip is powered,
unless a new authentication is initialized or RST becomes active. If the new authentica-
tion request is not validated, the card loses its previous authentication and it should be
presented again. Only the last request is memorized.
Note:
Password and authentication may be presented at any time and in any order. If the trials
limit has been reached (after four consecutive incorrect attempts), the password verifica-
tion or authentication process will not be taken into account.
Figure 13. Password and Authentication Operations
2024HS–SMEM–04/07
VERIFY RPW
DATA
Checksum (CS)
VERIFY CS
Write DATA
VERIFY CS
CS
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