X24320
Clock and Data Conventions
DEVICE OPERATION
The device supports a bidirectional bus oriented
protocol. The protocol defines any device that sends
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.
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
Start Condition
All commands are preceded by the start condition,
which is a HIGH to LOW transition of SDA when SCL
and provide the clock for both transmit and receive
operations. Therefore, the device will be
is HIGH. The device continuously monitors the SDA and
SCL lines for the start condition and will not
considered a slave in all applications.
respond to any command until this condition has been met.
Figure 1. Data Validity
SCL
SDA
DATA
CHANGE
DATA STABLE
7035 FM 03
Figure 2. Definition of Start and Stop
SCL
SDA
START BIT
STOP BIT
7035 FM 04
3
ICMIC [ IC MICROSYSTEMS ]
