Atmel ARM-Based Evaluation Kit AT91SAM9N12-EK AT91SAM9N12-EK Data Sheet

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SAM9N12/SAM9CN11/SAM9CN12 [DATASHEET]

11063K–ATARM–05-Nov-13

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 

Each transfer begins with a START condition and terminates with a STOP condition (see 



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.

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