AT45DB021D-SSH-B-RET Atmel, AT45DB021D-SSH-B-RET Datasheet - Page 16

• Manufacturer Part Number: AT45DB021D-SSH-B-RET
• Manufacturer: Atmel

8.1.1
8.1.2
16
Sector Lockdown Register
Sector Lockdown Register is a nonvolatile register that contains 8-bytes of data, as shown below:
Table 8-2.
Table 8-3.
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
one and the last byte (byte eight) corresponds to sector seven. After the last byte of the Sector Lockdown 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 8-4
Table 8-4.
Figure 8-2.
Sector Number
Locked
Unlocked
Sectors 0a, 0b Unlocked
Sector 0a Locked (Page 0-7)
Sector 0b Locked (Page 8-127)
Sectors 0a, 0b Locked (Page 0-127)
Command
Read Sector Lockdown Register
Note:
CS
SO
Atmel AT45DB021D
SI
Each transition
represents 8 bits
xx = Dummy Byte
details the values read from the Sector Lockdown Register.
Sector Lockdown Register
Sector 0 (0a, 0b)
Sector Lockdown Register
Read Sector Lockdown Register
Opcode
X
X
Byte 1
35H
See Below
0 (0a, 0b)
X
(Page 0-7)
Bit 7, 6
Byte 2
Data Byte
0a
00
11
00
11
xxH
n
(Page 8-127)
Data Byte
Bit 5, 4
Byte 3
n + 1
0b
00
00
11
11
xxH
1 to 7
FFH
00H
Bit 3, 2
Byte 4
00
00
00
00
xxH
Data Byte
n + 3
Bit 1, 0
00
00
00
00
3638J–DFLASH–5/10
Value
Data
C0H
00H
30H
F0H