AT88SC0104C datasheet(49/58 Pages) ATMEL

49 / 58 page

5210B–SMIC–11/08

AT88SC0104/0204/0404/0808/1616/3216/6416/12816/25616C

Initialization Example

9.1

Write Data to User Zones

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.

9.2

Unlock 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 Con-

fig Zone command to read back the security code at address $E9 for verification that the

configuration memory has been unlocked.

9.3

Write Data to Configuration Memory

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.

9.4

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 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.

Zone Configuration Example

User Zone

Data

Security Requirements

Access

Password/Key

Zone 0 Data

None

$FF

Zone 1 Data

Read/Write Password (Set 1)

$7F

$F9

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