AT45DB321E datasheet(34/80 Pages) RENESAS

34 / 80 page

DS-AT45DB321E-8784 Rev. N

Page 34

9/1/23

AT45DB321E Datasheet

8.1.1

Read Sector Lockdown Register

The nonvolatile Sector Lockdown Register specifies which sectors in the main memory are currently unlocked or

have been permanently locked down. The Sector Lockdown Register is a read-only register and contains 64 bytes

of data which correspond to Sectors 0 through 63. To read the Sector Lockdown Register, an opcode of 35h must

be clocked into the device followed by three dummy bytes. After the last bit of the opcode and dummy bytes have

been clocked in, the data for the contents of the Sector Lockdown Register are clocked out on the SO pin. The first

byte (byte location 0) corresponds to Sector 0 (0a and 0b), the second byte corresponds to Sector 1, and the last

byte (byte location 63) corresponds to Sector 63. After the last byte of the Sector Lockdown Register has been

read, additional pulses on the SCK pin result in undefined data being output on the SO pin.

Deasserting the CS pin terminates the Read Sector Lockdown Register operation and put the SO pin into a high-

impedance state. Table 15 details the format the Sector Lockdown Register.

Table 15. Sector Lockdown Register

Table 16. Sector 0 (0a and 0b) Sector Lockdown Register Byte Value

Table 17. Read Sector Lockdown Register Command

Figure 12. Read Sector Lockdown Register

Sector Number

0 (0a, 0b)

1 to 63

Locked

See Table 16

FFh

Unlocked

00h

Bit 7:6

Bit 5:4

Bit 3:2

Bit 1:0

Data

Value

Sector 0a

(Page 0-7)

Sector 0b

(Page 8-127)

N/A

Sectors 0a and 0b Unlocked

00h

Sector 0a Locked

C0h

Sector 0b Locked

30h

Sectors 0a and 0b Locked

F0h

Command

Byte 1

Byte 2

Byte 3

Byte 4

Read Sector Lockdown Register

35h

XXh

35h

Data

n + 1

Data

n + 63

Each transition represents eight bits

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