AT45DB021D_09 Datasheet, PDF (17/54 Pages) ATMEL Corporation – 2-megabit 2.7-volt Minimum DataFlash

AT45DB021D
9.1.3
Read Sector Protection Register Command
To read the Sector Protection Register, the CS pin must first be asserted. Once the CS pin has
been asserted, an opcode of 32H and 3 dummy bytes must be clocked in via the SI pin. After the
last bit of the opcode and dummy bytes have been clocked in, any additional clock pulses on the
SCK pins will result in data for the content of the Sector Protection Register being output on the
SO pin. The first byte corresponds to sector 0 (0a, 0b), the second byte corresponds to sector 1,
the third byte corresponds to sector 2, and the last byte (byte 4) corresponds to sector 3. Once
the last byte of the Sector Protection Register has been clocked out, any additional clock pulses
will result in undefined data being output on the SO pin. The CS must be deasserted to termi-
nate the Read Sector Protection Register operation and put the output into a high-impedance
state.
Command
Read Sector Protection Register
Note: xx = Dummy Byte
Byte 1
32H
Figure 9-4. Read Sector Protection Register
CS
Byte 2
xxH
Byte 3
xxH
Byte 4
xxH
SI
Opcode
X
X
X
SO
Each transition
represents 8 bits
Data Byte
n
Data Byte
n+1
Data Byte
n+3
9.1.4
Various Aspects About the Sector Protection Register
The Sector Protection Register is subject to a limit of 10,000 erase/program cycles. Users are
encouraged to carefully evaluate the number of times the Sector Protection Register will be
modified during the course of the applications’ life cycle. If the application requires that the Sec-
tor Protection Register be modified more than the specified limit of 10,000 cycles because the
application needs to temporarily unprotect individual sectors (sector protection remains enabled
while the Sector Protection Register is reprogrammed), then the application will need to limit this
practice. Instead, a combination of temporarily unprotecting individual sectors along with dis-
abling sector protection completely will need to be implemented by the application to ensure that
the limit of 10,000 cycles is not exceeded.
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