Datasheet

11XX
DS22067J-page 12  2011 Microchip Technology Inc.
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 “Write Enable (WREN)
and Write Disable (WRDI) Instructions”).
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.
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.
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.
FIGURE 4-3: WRITE COMMAND SEQUENCE
Note: If a NoMAK is generated before any
data has been provided, or if a standby
pulse occurs before the NoMAK is gen-
erated, the 11XX will be reset, and the
write cycle will not be initiated.
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.
7654
Data Byte 1
3210
7654
Data Byte 2
3210
7654
Data Byte n
3210
SCIO
MAK
MAK
No MAK
11010100
Start Header
SCIO
Device Address
MAK
00
(1)
001010
MAK
Command
10101100
MAK
NoSAK
SAK
Standby Pulse
SCIO
SAK
15 14 13 12
Word Address MSB
11 10 9 8
MAK
SAK
7654
Word Address LSB
3210
MAK
SAK
SAK
SAK
SAK
Twc
Note 1: For the 11XXXX1, this bit must be a ‘1’.