X24128
DEVICE OPERATION
The device supports a bidirectional bus oriented
protocol. 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 trans-
fers, and provide the clock for both transmit and
receive operations. Therefore, the device 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
reserved 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 device 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
SCL
SDA
DATA STABLE
DATA
CHANGE
7027 FM 03
Figure 2. Definition of Start and Stop
SCL
SDA
START BIT
STOP BIT
7027 FM 04
3
XICOR [ XICOR INC. ]
