M34A02

6/15

Figure 7. Write Mode Sequences with WC=0 (data write enabled)

BYTE WRITE

DEV SEL

BYTE ADDR

DATA IN

WC

PAGE WRITE

DEV SEL

BYTE ADDR

DATA IN 1

DATA IN 2

WC

DATA IN 3

AI02804

PAGE WRITE

(cont'd)

WC (cont'd)

DATA IN N

ACK

R/W

ACK

ACK

ACK

ACK

ACK

ACK

R/W

ACK

ACK

Write Operations

Following a Start condition the bus master sends

a Device Select code with the RW bit reset to 0.

The device acknowledges this, as shown in Figure

6, and waits for one address byte. The device

responds to the address byte with an acknowledge

bit, and then waits for the data byte.

Writing to the memory may be inhibited if Write

Control (WC) is taken High. Any Write instruction

with Write Control (WC) held High (during a period

of time from the Start condition until the end of the

address

byte)

will not modify

the

memory

contents, and the accompanying data bytes are

Each data byte in the memory has a 8-bit address.

When the bus master generates a Stop condition

slot), either at the end of a Byte Write or a Page

Write, the internal memory Write cycle is triggered.

A Stop condition at any other time does not trigger

the internal Write cycle.

During the internal Write cycle, Serial Data (SDA)

is disabled internally, and the device does not

respond to any requests (and sends NoAck in

reply to them).

Byte Write

After the Device Select code and the address byte,

the bus master sends one data byte. If the

addressed location is Write-protected, by Write

Control (WC), the device replies with NoAck, and

the location is not modified. If, instead, the

addressed location is not Write-protected, the

device

replies

with

Ack.

The

bus

master

terminates the transfer by generating a Stop

condition, as shown in Figure 6.

Page Write

The Page Write mode allows up to 16 bytes to be

written in a single write cycle, provided that they

are all located in the same ’row’ in the memory:

that is the most significant memory address bits

(b7-b4) are the same. If more bytes are sent than

will fit up to the end of the row, a condition known