SAM9M11_14 Datasheet, PDF (923/1488 Pages) ATMEL Corporation – Atmel | SMART ARM-based Embedded MPU

39.5 Functional Description
39.5.1 USB V2.0 High Speed Device Port Introduction
The USB V2.0 High Speed Device Port provides communication services between host and attached USB
devices. Each device is offered with a collection of commu nication flows (pipes) associated with each endpoint.
Software on the host communicates with a USB Device through a set of communication flows.
39.5.2 USB V2.0 High Speed Transfer Types
A communication flow is carried over one of four transfer types defined by the USB device.
A device provides several logical communication pipes with the host. To each log ical pipe is associated an
endpoint. Transfer through a pipe belongs to one of the four transfer types:
 Control Transfers: Used to configure a device at attach time and can be used for other device-specific
purposes, including control of other pipes on the device.
 ?Bulk Data Transfers: Generated or consumed in relatively large burst quantities and have wide dynamic
latitude in transmission constraints.
 ?Interrupt Data Transfers: Used for timely but reliable delivery of data, for example, characters or
coordinates with human-perceptible echo or feedback response characteristics.
 Isochronous Data Transfers: Occupy a prenegotiated amount of USB bandwidth with a prenegotiated
delivery latency. (Also called streaming real time transfers.)
As indicated below, transfers are sequential events carried out on the USB bus.
Endpoints must be configured according to the transfer type they handle.
Table 39-2. USB Communication Flow
Transfer
Direction
Control
Bidirectional
Isochronous
Unidirectional
Interrupt
Unidirectional
Bulk
Unidirectional
Bandwidth
Not guaranteed
Guaranteed
Not guaranteed
Not guaranteed
Endpoint Size
8,16,32,64
8-1024
8-1024
8-512
Error Detection
Yes
Yes
Yes
Yes
Retrying
Automatic
No
Yes
Yes
39.5.3 USB Transfer Event Definitions
A transfer is composed of one or several transactions;
Table 39-3. USB Transfer Events
CONTROL
(bidirectional)
Control Transfers ⁽¹⁾
IN
(device toward host)
OUT
(host toward device)
Bulk IN Transfer
Interrupt IN Transfer
Isochronous IN Transfer ⁽²⁾
Bulk OUT Transfer
Interrupt OUT Transfer
Isochronous OUT Transfer ⁽²⁾
• Setup transaction → Data IN transactions →Status OUT transaction
• Setup transaction → Data OUT transactions →Status IN transaction
• Setup transaction → Status IN transaction
• Data IN transaction → Data IN transaction
• Data IN transaction → Data IN transaction
• Data IN transaction → Data IN transaction
• Data OUT transaction → Data OUT transaction
• Data OUT transaction → Data OUT transaction
• Data OUT transaction → Data OUT transaction
SAM9M11 [DATASHEET]
Atmel-6437F-ATARM-SAM9M11-Datasheet_21-Oct-14
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