Datasheet

11AA02E48/11AA02E64
DS20002122B-page 12  2008-2013 Microchip Technology Inc.
4.4 Write Enable (WREN) and Write
Disable (WRDI) Instructions
The 11AA02EXX 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
completed internally. The
WREN instruction will set the
latch, and the
WRDI instruction will reset the latch.
The following is a list of conditions under which the
write enable latch will be reset:
• Power-up
•
WRDI instruction successfully executed
• WRSR instruction successfully executed
•
WRITE instruction successfully executed
• ERAL instruction successfully executed
• SETAL instruction successfully executed
FIGURE 4-4: WRITE ENABLE COMMAND SEQUENCE
FIGURE 4-5: WRITE DISABLE COMMAND SEQUENCE
Note: The WREN and WRDI instructions 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 responding with a
SAK or executing the command.
11010100
Start Header
SCIO
Device Address
MAK
00001010
MAK
Command
10010011
NoMAK
NoSAK
SAK
Standby Pulse
SCIO
SAK
11010100
Start Header
SCIO
Device Address
MAK
00001010
MAK
Command
01010010
NoMAK
NoSAK
SAK
Standby Pulse
SCIO
SAK