AT45DB041D
10.1.1
Sector Lockdown Register
Sector Lockdown Register is a nonvolatile register that contains 16 bytes of data, as shown
below:
Sector Number
Locked
0 (0a, 0b)
1 to 7
FFH
00H
See Below
Unlocked
Table 10-1. Sector 0 (0a, 0b)
0a
(Page 0-7)
Bit 7, 6
00
0b
(Page 8-255)
Data
Value
Bit 5, 4
00
Bit 3, 2
00
Bit 1, 0
Sectors 0a, 0b Unlocked
00
00
00
00
00H
C0H
30H
F0H
Sector 0a Locked (Page 0-7)
Sector 0b Locked (Page 8-255)
Sectors 0a, 0b Locked (Page 0-255)
11
00
00
00
11
00
11
11
00
10.1.2
Reading the Sector Lockdown Register
The Sector Lockdown Register can be read to determine which sectors in the memory array are
permanently locked down. To read the Sector Lockdown Register, the CS pin must first be
asserted. Once the CS pin has been asserted, an opcode of 35H and 3 dummy bytes must be
clocked into the device via the SI pin. After the last bit of the opcode and dummy bytes have
been clocked in, the data for the contents of the Sector Lockdown Register will be clocked out
on the SO pin. The first byte corresponds to sector 0 (0a, 0b) the second byte corresponds to
sector 1 and the las byte (byte 8) corresponds to sector 7. After the last byte of the Sector Lock-
down Register has been read, additional pulses on the SCK pin will simply result in undefined
data being output on the SO pin.
Deasserting the CS pin will terminate the Read Sector Lockdown Register operation and put the
SO pin into a high-impedance state.
Table 10-2 details the values read from the Sector Lockdown Register.
Table 10-2. Sector Lockdown Register
Command
Byte 1
Byte 2
Byte 3
Byte 4
Read Sector Lockdown Register
35H
xxH
xxH
xxH
Note:
xx = Dummy Byte
Figure 10-2. Read Sector Lockdown Register
CS
Opcode
X
X
X
SI
Data Byte
Data Byte
n + 1
Data Byte
n + 7
SO
n
Each transition
represents 8 bits
19
3595L–DFLASH–4/08
ATMEL [ ATMEL ]
