AT45DB321D ATMEL [ATMEL Corporation], AT45DB321D Datasheet - Page 19

• Manufacturer Part Number: AT45DB321D
• Description: 32-megabit 2.7-volt DataFlash
• Manufacturer: ATMEL [ATMEL Corporation]

10.1.1
10.1.2
Figure 10-2. Read Sector Lockdown Register
3597J–DFLASH–4/08
CS
SO
Sector Lockdown Register
Reading the Sector Lockdown Register
SI
Each transition
represents 8 bits
Opcode
Sector Lockdown Register is a nonvolatile register that contains 64 bytes of data, as shown
below:
Table 10-1.
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 last byte (byte 16) corresponds to sector 15. After the last byte of the Sector
Lockdown Register has been read, additional pulses on the SCK pin will simply result in unde-
fined 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
Table 10-2.
Sector Number
Locked
Unlocked
Sectors 0a, 0b Unlocked
Sector 0a Locked (Pages 0-7)
Sector 0b Locked (Pages 8-127)
Sectors 0a, 0b Locked (Pages 0-127)
Command
Read Sector Lockdown Register
Note:
xx = Dummy Byte
details the values read from the Sector Lockdown Register.
X
Sector 0 (0a, 0b)
Sector Lockdown Register
X
X
(Pages 0-7)
Bit 7, 6
Data Byte
0a
00
11
11
00
n
Byte 1
35H
See Below
0 (0a, 0b)
(Pages 8-127)
Data Byte
n + 1
Bit 5, 4
0b
00
00
11
11
Byte 2
xxH
Bit 3, 2
00
00
00
00
AT45DB321D
Data Byte
Byte 3
n + 63
xxH
Bit 1, 0
1 to 63
FFH
00H
00
00
00
00
Byte 4
xxH
Value
Data
C0H
F0H
00H
30H
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