X24325
Block Protect Bits
Programmable Hardware Write Protect
The Block Protect Bits BP0 and BP1 determine which
blocks of the memory are write-protected:
The Write Protect (WP) pin and the Write Protect
Enable (WPEN) bit in the Write Protect Register
control the programmable hardware write protect
feature. Hardware write protection is enabled when the
WP pin and the WPEN bit are both HIGH, and
disabled when either the WP pin is LOW or the WPEN
bit is LOW. When the chip is hardware write-protected,
nonvolatile writes are disabled to the Write Protect
Register, including the BP bits and the WPEN bit itself,
as well as to block-protected sections in the memory
array. Only the sections of the memory array that are
not block-protected can be written. Note that since the
WPEN bit is write-protected, it cannot be changed
back to a LOW state, and write protection is disabled
as long as the the WP pin is held HIGH. Table 2
defines the write protection status for each state of
WPEN and WP.
Table 1. Block Protect Bits
Protected
BP1 BP0 Addresses
0
0
1
0
1
0
None
C00h–FFFh
800h–FFFh
Upper 1/4
Upper 1/2
Full Array (WPR
not included)
1
1
0000h–FFFh
6552 FRM T02
Table 2. Write Protect Status Table
Memory Array
(Not Block
Protected)
Memory Array
(Block Protected)
WP
0
WPEN
BP Bits
Writable
Writable
Protected
WPEN Bit
Writable
X
0
1
Writable
Writable
Writable
Protected
X
Protected
Writable
1
Protected
Protected
6552 FRM T03
10
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