Datasheet
SH1107
14
Start and Stop conditions
Both data and clock lines remain HIGH when the 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).
SDA
SCL
SDA
SCL
START condition STOP condition
S P
Figure 6 Start and Stop conditions
System configuration
l Transmitter: The device that sends the data to the bus.
l Receiver: The device that receives the data from the bus.
l Master: The device that initiates a transfer generates clock signals and terminates a transfer.
l Slave: The device addressed by a master.
l Multi-Master: More than one master can attempt to control the bus at the same time without corrupting the message
l Arbitration: Procedure to ensure that, if more than one master simultaneously tries to control the bus, only one is allowed
to do so and the message is not corrupted.
l Synchronization: Procedure to synchronize the clock signals of two or more devices.
MASTER
TRANSMITTER
/RECEIVER
SLAVE
RECEIVER
SLAVE
TRANSMITTER
/RECEIVER
MASTER
TRANSMITTER
MASTER
TRANSMITTER
/RECEIVER
SDA
SCL
Figure 7 System configuration
Acknowledge
Each byte of eight bits is followed by an acknowledge bit. The acknowledge bit is a HIGH signal put on the bus by the
transmitter during which time the master generates an extra acknowledge related clock pulse. A slave receiver which is
addressed must generate an acknowledge after the reception of each byte. Also a master receiver must generate an
acknowledge after the reception of each byte that has been clocked out of the slave transmitter. The device that acknowledges
must pull-down the SDA line during the acknowledge clock pulse, so that the SDA line is stable LOW during the HIGH period of
the acknowledge related clock pulse (set-up and hold times must be taken into consideration). A master receiver must signal an
end of data to the transmitter by not generating an acknowledge on the last byte that has been clocked out of the slave. In this
event the transmitter must leave the data line HIGH to enable the master to generate a stop condition.