AT88SC0104C datasheet(21/58 Pages) ATMEL

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5210B–SMIC–11/08

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

When PM = “11”, the user zone under protection requires no password. When PM = “10”, the

zone requires Write Password verification for writing and reading is free. When PM = “01” or

“00”, reading requires the read password verification and writing requires write password verifi-

cation. However, proper verification of the Write Password also grants read access. The

password set required is specified by PW(3:0) in the corresponding Passwords/Keys Register

(see following section). Verification of the Write password also allows modification of the read

and the write passwords.

5.3.9.2

AM(1:0) – Authentication mode

The AM bits allow configuration of the authentication modes and only available under the

authentication mode of operation.

5.3.9.3

ER – Encryption Required

The use of the ER bit is applicable in the encryption mode of operation.

5.3.9.4

WLM – Write Lock Mode

Asserting this bit (WLM = “0”) divides the user zone into 8-byte pages. The first byte of each

page becomes the Write Lock Byte and defines the locked/unlocked status for each byte in the

page. Write access is forbidden to a byte if its associated bit in the Write Lock Byte is set to “0”.

Bit 7 controls byte 7; bit 6 controls byte 6, etc. Setting bit 0 to “0” locks the Write Lock Byte itself.

Enabling Write Lock Mode limits write operations to one byte at a time.

5.3.9.5

MDF – Modify Forbidden

Asserting this bit (MDF = “0”) renders the user zone read-only at all times. The user zone must,

therefore, be programmed before setting this bit to “0”

5.3.9.6

PGO – Program Only

Asserting this bit (PGO = “0”) allows changing of data within the user zone under protection from

“1” to “0” and never from “0” to “1”.

5.3.10

Password/Key Registers

Four, eight or sixteen 8-bit Password/Key registers receive definition during device personaliza-

tion. Each Password/Key register works in conjunction with a corresponding Access register to

define the security settings of each zone. The values programmed have an immediate affect on

the logic of the device. The default value is “1” for each bit. Bit 3 is reserved and should be left

as value “1.”

5.3.10.1

AK(1:0) – Authentication Key

The AK bits are applicable under the authentication mode of operation.

5.3.10.2

POK(1:0) – Program Only Key

The POK bits are applicable under the authentication mode of operation.

Table 5-6.

Password/Key Register Definition

Bit 7

Bit 6

Bit 5

Bit4

Bit 3

Bit 2

Bit 1

Bit 0

AK1

AK0

POK1

POK0

Resv

PW2

PW1

PW0

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