Samsung S3C2451X User Manual page 407

S3C2451X RISC MICROPROCESSOR
18
OVERVIEW
The S3C2451X RISC microprocessor can support two channels of multi-master IIC-bus serial interface. A
dedicated serial data line (SDA) and a serial clock line (SCL) carry information between bus masters and
peripheral devices which are connected to the IIC-bus. The SDA and SCL lines are bi-directional.
In multi-master IIC-bus mode, multiple S3C2451X RISC microprocessors can receive or transmit serial data to or
from slave devices. The master S3C2451X can initiate and terminate a data transfer over the IIC-bus. The IIC-bus
in the S3C2451X uses Standard bus arbitration procedure.
To control multi-master IIC-bus operations, values must be written to the following registers:
— Multi-master IIC-bus control register, IICCON
— Multi-master IIC-bus control/status register, IICSTAT
— Multi-master IIC-bus Tx/Rx data shift register, IICDS
— Multi-master IIC-bus address register, IICADD
When the IIC-bus is free, the SDA and SCL lines should be both at High level. A High-to-Low transition of SDA
can initiate a Start condition. A Low-to-High transition of SDA can initiate a Stop condition while SCL remains
steady at High Level.
The Start and Stop conditions can always be generated by the master devices. A 7-bit address value in the first
data byte, which is put onto the bus after the Start condition has been initiated, can determine the slave device
which the bus master device has selected. The 8th bit determines the direction of the transfer (read or write).
Every data byte put onto the SDA line should be eight bits in total. The bytes can be unlimitedly sent or received
during the bus transfer operation. Data is always sent from most-significant bit (MSB) first, and every byte should
be immediately followed by acknowledge (ACK) bit.
IIC-BUS INTERFACE
Preliminary product information describe products that are in development,
for which full characterization data and associated errata are not yet available.
Specifications and information herein are subject to change without notice.
IIC-BUS INTERFACE
18-1