CAT15008, CAT15016
© 2008 SCILLC. All rights reserved. 7 Doc. No. MD-1125 Rev. B
Characteristics subject to change without notice
STATUS REGISTER
The Status Register, as shown in Table 2, contains a
number of status and control bits.
The RDY
¯¯¯¯ (Ready) bit indicates whether the device is
busy with a write operation. This bit is automatically
set to 1 during an internal write cycle, and reset to 0
when the device is ready to accept commands. For
the host, this bit is read only.
The WEL (Write Enable Latch) bit is set/reset by the
WREN/WRDI commands. When set to 1, the device is
in a Write Enable state and when set to 0, the device
is in a Write Disable state.
The BP0 and BP1 (Block Protect) bits determine which
blocks are currently write protected. They are set by the
user with the WRSR command and are non-volatile. The
user is allowed to protect a quarter, one half or the entire
memory, by setting these bits according to Table 3. The
protected blocks then become read-only.
The WPEN (Write Protect Enable) bit acts as an enable
for the WP
¯¯¯ pin. Hardware write protection is enabled
when the WP
¯¯¯ pin is low and the WPEN bit is 1. This
condition prevents writing to the status register and to
the block protected sections of memory. While
hardware write protection is active, only the non-block
protected memory can be written. Hardware write
protection is disabled when the WP
¯¯¯ pin is high or the
WPEN bit is 0. The WPEN bit, WP
¯¯¯ pin and WEL bit
combine to either permit or inhibit Write operations, as
detailed in Table 4.
Table 2. Status Register
7 6 5 4 3 2 1 0
WPEN 0 0 0 BP1 BP0 WEL RDY¯¯¯¯
Table 3. Block Protection Bits
Status Register Bits
BP1 BP0
Array Address Protected Protection
0 0 None No Protection
15008: 0300-03FF
0 1
15016: 0600-07FF Quarter Array Protection
15008: 0200-03FF
1 0
15016: 0400-07FF Half Array Protection
15008: 0000-03FF
1 1
15016: 0000-07FF Full Array Protection
Table 4. Write Protect Enable Operation
WPEN WP
¯¯¯ WEL Protected Blocks Unprotected Blocks Status Register
0 X 0 Protected Protected Protected
0 X 1 Protected Writable Writable
1 Low 0 Protected Protected Protected
1 Low 1 Protected Writable Protected
X High 0 Protected Protected Protected
X High 1 Protected Writable Writable