AT88SC0404CA-Y6H-T Atmel, AT88SC0404CA-Y6H-T Datasheet - Page 41

• Manufacturer Part Number: AT88SC0404CA-Y6H-T
• Description: IC EEPROM 4KBIT 4MHZ 8MAP
• Manufacturer: Atmel
• Series: CryptoMemory®r

Specifications of AT88SC0404CA-Y6H-T

• Format - Memory: EEPROMs - Serial
• Memory Type: EEPROM
• Memory Size: 4K (512 x 8)
• Speed: 4MHz
• Interface: I²C, 2-Wire Serial
• Voltage - Supply: 2.7 V ~ 3.6 V
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 8-UDFN Exposed Pad
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

9.
9.1.
9.2.
9.3.
9.4.
40
Initialization Example
The first step in initializing Atmel
security settings need to be to protect this data. Once defined, determine the proper settings for CryptoMemory
registers and select values for passwords. To initialize the CryptoMemory device, the following sequence is
recommended to take place in a secure location to protect sensitive data and passwords that may be loaded into the
device.
Write Data to User Zones
In the Atmel default configuration, all user zones have free access rights. Writing initial data into the user zones should
be done before setting security configurations. Use the Set User Zone command and Write User Zone command to
write initial data into the user zones. The Read User Zone command may be used to verify the data written.
Unlock the Configuration Memory
Before any data can be written to the configuration zone, it must be unlocked by presenting the correct security code
(Write 7 Password). Use the Verify Password command with the proper secure code supplied by Atmel to unlock the
configuration zone. Use the Read Config Zone command to read back the security code at address $E9 for verification
that the configuration zone has been unlocked.
Write Data to the Configuration Memory
Writing this data is accomplished by performing the Write Config Zone command at the appropriate address location.
The Read Config Zone command may be used to verify the data written. As soon as values are written to the registers,
keys, and passwords, they become effective in determining the security of the user zones.
Set Security Fuses
Once all data is written and verified into user zones and the configuration zone the security fuses should be set before
the device is released from the secure location used for device initialization. There are three fuses, FAB, CMA and PER
that must be set. These three fuses must be set in the order listed (FAB, then CMA, then PER). The Write Fuse
command is used to set each of the three fuses individually. The Read Fuse command may be used to check the
status of all three fuses. Once all fuses have been set the Read Fuse command should return a value of zero for the
second nibble of the fuse byte.
The Atmel AT88SC0104CA is used for this example. A small pattern is written into the first two user zones. Security for
each of these two user zones and the associated register values are shown in the table below. Simple values for
passwords are used.
Table 24. Atmel CryptoMemory Asynchronous Command Set
Atmel AT88SC0104/0204/0404/0808/CA
User Zone
0
1
2
3
Zone 0 Data
Zone 1 Data
Zone 2 Data
Zone 3 Data
Data
®
CryptoMemory
None
Read/Write Password (Set 1)
Read/Write Authentication (Set 2)
Read/Write Password (Set 1),
Read/Write Authentication (Set 2)
with Encryption Required
Security Requirements
®
is to determine what data is to be stored in the device and what the
Access Register
$DF
$FF
$7F
$57
Password/Key
Register
8664C–CRYPT–01/10
$BF
$FF
$F9
$B9