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

520

SAM9N12/SAM9CN11/SAM9CN12 [DATASHEET]

11063K–ATARM–05-Nov-13

The USB V2.0 full-speed provides communication services between host and attached USB devices. Each device is
offered with a collection of communication flows (pipes) associated with each endpoint. Software on the host
communicates with a USB device through a set of communication flows. 

The Control Transfer endpoint EP0 is always used when a USB device is first configured (USB v. 2.0 specifications). 

A communication flow is carried over one of four transfer types defined by the USB device. 

Each transfer results in one or more transactions over the USB bus. There are three kinds of transactions flowing across
the bus in packets:

1.

Setup Transaction

2.

Data IN Transaction

3.

Data OUT Transaction

EP0

USB Host V2.0

Software Client 1

Software Client 2

Data Flow: Bulk Out Transfer

Data Flow: Bulk In Transfer

Data Flow: Control Transfer

Data Flow: Control Transfer

EP1

EP2

USB Device 2.0 
Block 1

USB Device 2.0 
Block 2

EP5

EP4

EP0

Data Flow: Isochronous In Transfer

Data Flow: Isochronous Out Transfer

USB Device endpoint configuration requires that
in the first instance Control Transfer must be EP0.

Control

Bidirectional

Not guaranteed

8, 16, 32, 64

Yes

Automatic

Isochronous

Unidirectional

Guaranteed

512

Yes

No

Interrupt

Unidirectional

Not guaranteed

≤ 64

Yes

Yes

Bulk

Unidirectional

Not guaranteed

8, 16, 32, 64

Yes

Yes