11AAXXX/11LCXXX
Upon receipt of each word, the four lower-order
Address Pointer bits are internally incremented by one.
The higher-order bits of the word address remain con-
stant. If the master should transmit data past the end of
the page, the address counter will roll over to the begin-
ning of the page, where further received data will be
written.
4.3
Write Instruction
Prior to any attempt to write data to the 11XX, the write
enable latch must be set by issuing the WREN
instruction (see Section 4.4).
Once the write enable latch is set, the user may pro-
ceed with issuing a WRITE instruction (including the
header and device address bytes) followed by the MSB
and LSB of the Word Address. Once the last Acknowl-
edge sequence has been performed, the master
transmits the data byte to be written.
Note: Page write operations are limited to writ-
ing bytes within a single physical page,
regardless of the number of bytes actu-
ally being written. Physical page bound-
aries start at addresses that are integer
multiples of the page size (16 bytes) and
end at addresses that are integer multi-
ples of the page size minus 1. As an
example, the page that begins at
address 0x30 ends at address 0x3F. If a
page Write command attempts to write
across a physical page boundary, the
result is that the data wraps around to
the beginning of the current page (over-
writing data previously stored there),
instead of being written to the next page
as might be expected. It is therefore
necessary for the application software to
prevent page write operations that
would attempt to cross a page bound-
ary.
The 11XX features a 16-byte page buffer, meaning that
up to 16 bytes can be written at one time. To utilize this
feature, the master can transmit up to 16 data bytes to
the 11XX, which are temporarily stored in the page buf-
fer. After each data byte, the master sends a MAK, indi-
cating whether or not another data byte is to follow. A
NoMAK indicates that no more data is to follow, and as
such will initiate the internal write cycle.
Note: If a NoMAK is generated before any data
has been provided, or if a standby pulse
occurs before the NoMAK is generated,
the 11XX will be reset, and the write
cycle will not be initiated.
FIGURE 4-3:
WRITE 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
Word Address LSB
Command
Word Address MSB
7 6 5 4 3 2 1 0
15 14 13 12 11 10 9 8
SCIO
0 1 1 0 1 1 0 0
Data Byte n
Data Byte 2
Data Byte 1
7 6 5 4 3 2 1 0
SCIO
7 6 5 4 3 2 1 0
7 6 5 4 3 2 1 0
Twc
DS22067E-page 12
Preliminary
© 2008 Microchip Technology Inc.
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