Datasheet

Table Of Contents
709
SAM9N12/SAM9CN11/SAM9CN12 [DATASHEET]
11063K–ATARM–05-Nov-13
39.7 Functional Description
39.7.1 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 39-4).
Each transfer begins with a START condition and terminates with a STOP condition (see Figure 39-3).
A high-to-low transition on the TWD line while TWCK is high defines the START condition.
A low-to-high transition on the TWD line while TWCK is high defines a STOP condition.
Figure 39-3. START and STOP Conditions
Figure 39-4. Transfer Format
39.7.2 Modes of Operation
The TWI has different modes of operations:
Master transmitter mode
Master receiver mode
Multi-master transmitter mode
Multi-master receiver mode
Slave transmitter mode
Slave receiver mode
These modes are described in the following sections.
TWD
TWCK
Start Stop
TWD
TWCK
Start Address R/W Ack Data Ack Data Ack Stop