ATAES132-SH-EQ-T Atmel, ATAES132-SH-EQ-T Datasheet - Page 56

• Manufacturer Part Number: ATAES132-SH-EQ-T
• Description: EEPROM AES 32Kbit EE SPI
• Manufacturer: Atmel

Specifications of ATAES132-SH-EQ-T

• Rohs: yes
• Maximum Clock Frequency: 10 MHz
• Operating Supply Voltage: 6 V
• Maximum Operating Temperature: - 40 C to + 85 C
• Mounting Style: SMD/SMT
• Package / Case: SOIC-8
• Interface Type: SPI
• Factory Pack Quantity: 4000

7.19.
7.19.2. User Zone ReadOnly Activation
Lock Command
The lock command permanently locks various segments of the EEPROM memory, including the configuration memory, the
key memory, and the SmallZone register. Key, Counter, and User Memory access restrictions are locked when the
configuration memory is locked. The SmallZone is locked independently of the other configuration memory registers.
Three registers in the configuration memory control the lock/unlock status of the memory segments:
If the lock control register contains 0x55, then the memory segment is unlocked. The lock command writes the specified lock
register to 0x00 to lock the segment. The lock control registers can only be written with the lock command, but they can always
be read with the BlockRead command. (See Section 7.4)
The lock command Param2 is an optional checksum (CRC-16) generated over the memory segment being locked. The value
in the checksum field must match the CRC-16 calculated within the device for the lock operation to succeed. If the lock
command returns a LockError ReturnCode, then the host system should re-write the memory segment and try the lock
operation again.
The Atmel recommendation is the key memory be locked immediately after loading the keys. See Appendix P for
personalization examples.
After the configuration memory is locked, the lock command can be used to activate the ReadOnly sser zone feature on
appropriately configured user zones. The lock command changes the user zone from read/write to read-only if the following
requirements are satisfied:
If lock command mode bits 2 is 1b, then the checksum field contains the CRC-16 of the user zone contents.
If ZoneConfig[Zone].WriteMode is 11b, then the command must include an InMAC generated using the KeyID stored in
ZoneConfig[Zone].WriteID, otherwise, the MAC is ignored.
The lock command changes the ZoneConfig[Zone].ReadOnly byte from 0x55 (read/write) to 0x00 when the ReadOnly feature
is activated. It is not possible to change a read-only User Zone to read/write after Configuration Memory is locked.
1.
2.
3.
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The configuration memory is controlled by the LockConfig register (see Section E.2.11)
The key memory is controlled by the LockKeys register (see Section E.2.9)
The SmallZone register is controlled by the LockSmall register (see Section E.2.10)
ZoneConfig[Zone].WriteMode must be 10b or 11b
Lock command mode bits 0 and 1 must be set to 11b
The Lock command zone field contains the target user zone number (Zone)
Atmel ATAES132 Preliminary Datasheet
8760A−CRYPTO−5/11
56