X24012

3

DEVICE OPERATION

The X24012 supports a bidirectional bus oriented proto-

col. The protocol defines any device that sends data

onto the bus as a transmitter, and the receiving device

as the receiver. The device controlling the transfer is a

master and the device being controlled is the slave. The

master will always initiate data transfers and provide the

clock for both transmit and receive operations. There-

fore, the X24012 will be considered a slave in all

applications.

Clock and Data Conventions

Data states on the SDA line can change only during SCL

LOW. SDA state changes during SCL HIGH are re-

served for indicating start and stop conditions. Refer to

Figures 1 and 2.

Start Condition

All commands are preceded by the start condition,

which is a HIGH to LOW transition of SDA when SCL is

HIGH. The X24012 continuously monitors the SDA and

SCL lines for the start condition and will not respond to

any command until this condition has been met.

Figure 1. Data Validity

Figure 2. Definition of Start and Stop

SCL

SDA

DATA STABLE

DATA

CHANGE

SCL

SDA

START BIT

STOP BIT

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