
IIC-BUS INTERFACE
S3C3410X RISC MICROPROCESSOR
14-2
IIC_BUS OPERATION
THE IIC-BUS INTERFACE
The S3C3410X IIC-bus interface has four operation modes:
— Master transmitter mode
— Master receive mode
— Slave transmitter mode
— Slave receive mode
Functional relationships among these operating modes are described below.
START AND STOP CONDITIONS
When the IIC-bus interface is in inactive state, it is usually in slave mode. In other word, the state of interface
should be in slave mode before detecting a Start condition on the SDA line. (A Start condition can be initiated by
having a High-to-Low transition of the SDA line while the clock signal of SCL is High) When the state of interface
is changed into the master mode, it can initiate a data transfer on the SDA line as well as generating the SCL
signal.
A Start condition can initiate a one-byte serial data transfer over the SDA line and stop condition can indicate the
termination of data transfer. A Stop condition is a Low-to-High transition of the SDA line while SCL is High. Start
and Stop conditions are always generated by the master. The IIC-bus is busy when a start condition is generated.
A few clocks after a stop condition, the IIC-bus will be free, again.
When a master initiates a Start condition, it should send slaver address to give a notice to the slaver device. The
one byte of address field consist of a 7-bit address and a 1-bit transfer direction indicator (that is, write or read).
If bit 8 is 0, it indicate a write operation(transmit operation). If bit 8 is 1, it indicate a request for data read(receive
operation).
The master will finish the transfer operation by transmitting a Stop condition. If the master want to continue the
data transmission the bus, it should generate another Start condition as well as slave address. In this way, the
read-write operation can be performed in various format.
SCL
SDA
SCL
Start
Condition
Stop
Condition
Figure 14-2. Start and Stop Condition