4

Device operation

The device supports the I2C protocol (see Figure 5). Any device that sends data on to the bus is defined a

transmitter, and any device that reads the data a receiver. The device that controls the data transfer is known as

the bus master, and the other as the slave device. A data transfer can only be initiated by the bus master, which

also provides the serial clock for synchronization. The device is always a slave in all communications.

Figure 5. I2C bus protocol

SCL

SDA

SCL

SDA

SDA

START

Condition

SDA

Input

SDA

Change

STOP

Condition

1

2

3

7

8

9

MSB

ACK

START

Condition

SCL

1

2

3

7

8

9

MSB

ACK

STOP

Condition

4.1

Start condition

Start is identified by a falling edge of serial data (SDA) while serial clock (SCL) is stable in the high state. A start

condition must precede any data transfer instruction. The device continuously monitors (except during a write

cycle) serial data (SDA) and serial clock (SCL) for a start condition.

4.2

Stop condition

Stop is identified by a rising edge of serial data (SDA) while serial clock (SCL) is stable and driven high. A stop

condition terminates communication between the device and the bus master. A Read instruction that is followed

by NoAck can be followed by a stop condition to force the device into the standby mode.

A stop condition at the end of a Write instruction triggers the internal write cycle.

4.3

Data input

During data input, the device samples serial data (SDA) on the rising edge of serial clock (SCL). For correct

device operation, serial data (SDA) must be stable during the rising edge of serial clock (SCL), and the serial data

(SDA) signal must change only when serial clock (SCL) is driven low.

M24C16-W M24C16-R M24C16-F

Device operation

DS9194 - Rev 11

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