AT88SC0404C-PI Atmel, AT88SC0404C-PI Datasheet - Page 40

• Manufacturer Part Number: AT88SC0404C-PI
• Manufacturer: Atmel

Specifications of AT88SC0404C-PI

• Operating Temperature (max): 85C
• Operating Temperature (min): -40C
• Package Type: PDIP
• Mounting: Through Hole
• Pin Count: 8
• Operating Temperature Classification: Industrial
• Lead Free Status / RoHS Status: Not Compliant

8.
8.1.
8.2.
8.3.
8.4.
5211C–SMIC–01/10
Atmel AT88SC0104/0204/0404/0808/1616/3216/6416/12816/25616C
Initialization Example
The first step in initializing Atmel
security settings need to be to protect this data. Once defined the proper settings for CryptoMemory registers can be
determined and values for passwords and keys may be selected. To initialize the CryptoMemory device the following
sequence is recommended to take place in a secure location to protect sensitive data, passwords and keys 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 memory, 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 memory. Use the Read Config Zone command to read back the security code at address $E9 for
verification that the configuration memory 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 memory 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 AT88SC0104C is used for this example. A small pattern is written into each of the four user zones. Security
for each of the four user zones and the associated register values are shown in the table below. Simple values for
codes, keys and passwords are used.
Table 32. Example Zones Configuration
The following shows the two-wire commands sent to the CryptoMemory device for the purpose of initializing the device.
The flow is consistent with the steps described above, comments have been added as indicated with an asterisk (*).
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
$BF
$FF
$F9
$B9
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