11XX
The following is a list of conditions under which the
write enable latch will be reset:
4.4
Write Enable (WREN) and Write
Disable (WRDI) Instructions
• Power-up
The 11XX contains a write enable latch. See Table 6-1
for the Write-Protect Functionality Matrix. This latch
must be set before any write operation will be com-
pleted internally. The WREN instruction will set the
latch, and the WRDIinstruction will reset the latch.
• WRDIinstruction successfully executed
• WRSRinstruction successfully executed
• WRITEinstruction successfully executed
• ERALinstruction successfully executed
• SETALinstruction successfully executed
Note: The WRENand WRDIinstructions must
be terminated with a NoMAK following
the command byte. If a NoMAK is not
received at this point, the command will
be considered invalid, and the device
will go into Idle mode without respond-
ing with a SAK or executing the com-
mand.
FIGURE 4-4:
WRITE ENABLE COMMAND SEQUENCE
Device Address
Standby Pulse
Start Header
SCIO
0 1 0 1 0 1 0 1
1 0 1 0 0 0 0 0(1)
Command
SCIO
1 0 0 1 0 1 1 0
Note 1: For the 11XXXX1, this bit must be a ‘1’.
FIGURE 4-5: WRITE DISABLE COMMAND SEQUENCE
Device Address
Standby Pulse
Start Header
SCIO
0 1 0 1 0 1 0 1
1 0 1 0 0 0 0 0(1)
Command
SCIO
1 0 0 1 0 0 0 1
Note 1: For the 11XXXX1, this bit must be a ‘1’.
2011 Microchip Technology Inc.
DS22067J-page 13
MICROCHIP [ MICROCHIP ]
