4.5

Device addressing

To start communication between the bus master and the slave device, the bus master must initiate a Start

condition. Following this, the bus master sends the device select code, shown in Table 3 (most significant bit first).

Table 3. Device select code

Device type identifier(1) Chip Enable address MSB address bits RW

b7

b6

b5

b4

b3

b2

b1

b0

Device select code when addressing the memory

array

1

0

1

0

E2(2)

A17

A16

RW

Device select code when addressing the

Identification page

1

0

1

1

E2(2)

X(3)

X(3)

RW

1. The most significant bit, b7, is sent first.

2. E2 bit value is compared to the logic level applied on the input pin E2.

3. X : Don't care bit

When the device select code is received, the device only responds if the chip enable address is the same as the

value on the chip enable (E2) input.

The 8th bit is the Read/Write bit (RW). This bit is set to 1 for read and 0 for write operations.

If a match occurs on the device select code, the corresponding device gives an acknowledgment on serial data

(SDA) during the 9th bit time. If the device does not match the device select code, it deselects itself from the bus,

and goes into standby mode after a stop condition.

M24M02-DR M24M02-R

Device addressing

DS7025 - Rev 11

page 9/40