Rainbow Electronics ISD5216 - Manual (Page 69)

I5216 SERIES
Advanced Information
PRELIMINARY
Publication Release Date: November 30, 2001
- 69 Revision A1
I
2
C SERIAL INTERFACE TECHNICAL INFORMATION
CHARACTERISTICS OF THE I
2
C SERIAL INTERFACE
The I 2 C interface is for bi-directional, two-line communication between different ICs or modules. The
two lines are a serial data line (SDA) and a serial clock line (SCL). Both lines must be connected to a
positive supply via a pull-up resistor. Data transfer may be initiated only when the interface bus is not
busy.
BIT TRANSFER
One data bit is transferred during each clock pulse. The data on the SDA line must remain stable
during the HIGH period of the clock pulse, as changes in the data line at this time will be interpreted as
a control signal.
START AND STOP CONDITIONS
Both data and clock lines remain HIGH when the interface bus is not busy. A HIGH-to-LOW transition
of the data line while the clock is HIGH is defined as the start condition (S). A LOW-to-HIGH transition
of the data line while the clock is HIGH is defined as the stop condition (P)
Bit transfer on the I C-bus
2
data line
stable;
data valid
change
of data
allowed
SDA
SCL
Definition of START and STOP conditions
handbook, full pagewidth
MBC622
SDA
SCL
P
STOP condition
SDA
SCL
S
START condition