6 read sector protection registers, Sck cs si so – Rainbow Electronics AT25DL081 User Manual
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AT25DL081 [DATASHEET]
8732D–DFLASH–12/2012
9.6
Read Sector Protection Registers
The Sector Protection Registers can be read to determine the current software protection status of each sector. Reading
the Sector Protection Registers, however, will not determine the status of the WP pin.
To read the Sector Protection Register for a particular sector, the CS pin must first be asserted and then the opcode 3Ch
must be clocked in. Once the opcode has been clocked in, three address bytes designating any address within the sector
must be clocked in. After the last address byte has been clocked in, the device will begin outputting data on the SO pin
during every subsequent clock cycle. The data being output will be a repeating byte of either FFh or 00h to denote the
value of the appropriate Sector Protection Register.
At clock frequencies above f
CLK
, the first byte of data output will not be valid. Therefore, if operating at clock frequencies
above f
CLK
, at least two bytes of data must be clocked out from the device in order to determine the correct status of the
appropriate Sector Protection Register.
Deasserting the CS pin will terminate the read operation and put the SO pin into a high-impedance state. The CS pin can
be deasserted at any time and does not require that a full byte of data be read.
In addition to reading the individual Sector Protection Registers, the Software Protection Status (SWP) bits in the Status
Register can be read to determine if all, some, or none of the sectors are software protected (refer to
Figure 9-5. Read Sector Protection Register
Table 9-3.
Read Sector Protection Register – Output Data
Output Data
Sector Protection Register Value
00h
Sector Protection Register value is 0 (sector is unprotected).
FFh
Sector Protection Register value is 1 (sector is protected).
SCK
CS
SI
SO
MSB
MSB
2
3
1
0
0
0
1
1
1
1
0
0
6
7
5
4
10 11
9
8
12
37 38
33
36
35
34
31 32
29 30
39 40
Opcode
A
A
A
A
A
A
A
A
A
MSB
MSB
D
D
D
D
D
D
D
D
D
D
Address Bits A23-A0
Data Byte
High-impedance