at88sc0104c ATMEL Corporation, at88sc0104c Datasheet - Page 51

• Manufacturer Part Number: at88sc0104c
• Description: Cryptomemory Specification For Standard Mode Of Operation
• Manufacturer: ATMEL Corporation

9. Initialization Example
9.1
9.2
9.3
9.4
5210A–SMIC–04/07
Write Data to User Zones
Unlock Configuration Memory
Write Data to Configuration Memory
Set Security Fuses
In the default configuration from Atmel, 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.
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 Con-
fig Zone command to read back the security code at address $E9 for verification that the
configuration memory has been unlocked.
Writing this data is accomplished by performing the Write Config Zone command at the appropri-
ate 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.
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 initial-
ization. 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 AT88SC0104C 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 9-1.
User Zone
0
1
AT88SC0104/0204/0404/0808/1616/3216/6416/12816/25616C
Zone Configuration Example
Zone 0 Data
Zone 1 Data
Data
Security Requirements
None
Read/Write Password (Set 1)
Register
Access
$FF
$7F
Password/Key
Register
$FF
$F9
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