Datasheet

721
SAM9G15 [DATASHEET]
11052D–ATARM–31-Oct-12
38.7 Functional Description
38.7.1 Transfer Format
The data put on the TWD line must be 8 bits long. Data is transferred MSB first; each byte must be followed by an
acknowledgement. The number of bytes per transfer is unlimited (see Figure 38-4).
Each transfer begins with a START condition and terminates with a STOP condition (see Figure 38-3).
z A high-to-low transition on the TWD line while TWCK is high defines the START condition.
z A low-to-high transition on the TWD line while TWCK is high defines a STOP condition.
Figure 38-3. START and STOP Conditions
Figure 38-4. Transfer Format
38.7.2 Modes of Operation
The TWI has different modes of operations:
z Master transmitter mode
z Master receiver mode
z Multi-master transmitter mode
z Multi-master receiver mode
z Slave transmitter mode
z Slave receiver mode
These modes are described in the following chapters.
TWD
TWCK
Start Stop
TWD
TWCK
Start Address R/W Ack Data Ack Data Ack Stop