24AA014_10 Datasheet, PDF (8/36 Pages) Microchip Technology – 1K I2C™ Serial EEPROM

24AA014/24LC014
6.0 WRITE OPERATIONS
6.1 Byte Write
Following the Start signal from the master, the device
code(4 bits), the Chip Select bits (3 bits) and the R/W
bit (which is a logic low) are placed onto the bus by the
master transmitter. The device will acknowledge this
control byte during the ninth clock pulse. The next byte
transmitted by the master is the word address and will
be written into the Address Pointer of the 24AA014/
24LC014. After receiving another Acknowledge signal
from the 24AA014/24LC014, the master device will
transmit the data word to be written into the addressed
memory location. The 24AA014/24LC014 acknowl-
edges again and the master generates a Stop
condition. This initiates the internal write cycle and the
24AA014/24LC014 will not generate Acknowledge
signals during this time (Figure 6-1). If an attempt is
made to write to the protected portion of the array when
the hardware write protection has been enabled, the
device will acknowledge the command, but no data will
be written. The write cycle time must be observed even
if write protection is enabled.
6.2 Page Write
The write-control byte, word address and the first data
byte are transmitted to the 24AA014/24LC014 in the
same way as in a byte write. But instead of generating
a Stop condition, the master transmits up to 15 addi-
tional data bytes to the 24AA014/24LC014 that are
temporarily stored in the on-chip page buffer and will be
written into the memory once the master has transmit-
ted a Stop condition. Upon receipt of each word, the
four lower order Address Pointer bits are internally
incremented by one.
The higher order four bits of the word address remain
constant. If the master should transmit more than 16
bytes prior to generating the Stop condition, the
address counter will roll over and the previously
received data will be overwritten. As with the byte write
operation, once the Stop condition is received, an inter-
nal write cycle will begin (Figure 6-2). If an attempt is
made to write to the protected portion of the array when
the hardware write protection has been enabled, the
device will acknowledge the command, but no data will
be written. The write cycle time must be observed even
if write protection is enabled.
Note:
Page write operations are limited to writ-
ing bytes within a single physical page,
regardless of the number of bytes
actually being written. Physical page
boundaries start at addresses that are
integer multiples of the page buffer size
(or ‘page size’) and end at addresses that
are integer multiples of [page size – 1]. 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 (overwriting
data previously stored there), instead of
being written to the next page, as might be
expected. It is therefore necessary that
the application software prevent page
write operations that would attempt to
cross a page boundary.
6.3 Write Protection
The WP pin must be tied to VCC or VSS. If tied to VCC,
the entire array will be write-protected. If the WP pin is
tied to VSS, write operations to all address locations are
allowed.
The WP pin is not available on the SOT-23 package.
FIGURE 6-1:
BYTE WRITE
S
Bus Activity
T
A
Master
R
T
Control
Byte
SDA Line
S
Word
Address
Bus Activity
A
A
C
C
K
K
Data
S
T
O
P
P
A
C
K
DS21809G-page 8
 2010 Microchip Technology Inc.