AT45DB021E datasheet(28/74 Pages) DIALOG

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AT45DB021E

DS-AT45DB021E—8789J—03/2021

9.1.1

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 eight

bytes of data which correspond to Sectors 0 through 7. 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 7) corresponds to Sector 7. 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 9-2 details the format the Sector Lockdown Register.

Table 9-2.

Sector Lockdown Register

Table 9-3.

Sector 0 (0a and 0b) Sector Lockdown Register Byte Value

Table 9-4.

Read Sector Lockdown Register Command

Figure 9-2. Read Sector Lockdown Register Timing

Sector Number

0 (0a, 0b)

1 to 7

Locked

See

Table 9-3

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

Each transition represents eight bits

Data

n + 7

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