at88sc153 ATMEL Corporation, at88sc153 Datasheet - Page 13

• Manufacturer Part Number: at88sc153
• Description: 3 X 64 X 8 Secure Memory With Authentication
• Manufacturer: ATMEL Corporation

9.6
1016E–SMEM–12/07
Verify Password
Figure 9-5.
Figure 9-6.
Note:
This command must be transmitted twice in sequence to successfully verify a write or read pass-
word. The first Verify Password command can be considered an initialization command. It will
write a new bit (“0”) in the PAC corresponding to the “r” and “p” bits. The data bits in this initial-
ization command are ignored. The second Verify Password command will compare the 3-byte
password data presented with the corresponding password value stored in memory. If the com-
parison is valid, the PAC will be cleared. For both commands, once the command sequence is
completed and a stop condition is issued, a nonvolatile write cycle is initiated to update the asso-
ciated attempts counter. After the stop condition is issued, an ACK polling sequence with the
specific command byte of $BD will indicate the end of the write cycle and will read the attempts
counter in the configuration zone. The initialization command will result in a “0” bit in the PAC.
The second Verify Password command will read $FF in the PAC if the verification was
successful.
Pw: Password, 3 bytes.
The two bits “rp” indicate the password to compare:
r = 0: Write password
r = 1: Read password
p: Password set number
rp = 01 for the secure code
Answer-to-reset Values
Verify Password
$2C
$AA
$55
$A1
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