Datasheet

SAM9261 [DATASHEET]
Atmel-6062O-ATARM-SAM9261-Datasheet_21-Jun-16
590
36.6.1.3 USB Transfer Event Definitions
As indicated below, transfers are sequential events carried out on the USB bus.
Notes: 1. Control transfer must use endpoints with no ping-pong attributes.
2. Isochronous transfers must use endpoints with ping-pong attributes.
3. Control transfers can be aborted using a stall handshake.
A status transaction is a special type of host-to-device transaction used only in a control transfer. The control
transfer must be performed using endpoints with no ping-pong attributes. According to the control sequence (read
or write), the USB device sends or receives a status transaction.
Figure 36-4. Control Read and Write Sequences
Notes: 1. During the Status IN stage, the host waits for a zero length packet (Data IN transaction with no data) from the
device using DATA1 PID. Refer to Chapter 8 of the Universal Serial Bus Specification, Rev. 2.0, for more
information on the protocol layer.
2. During the Status OUT stage, the host emits a zero length packet to the device (Data OUT transaction with no
data).
Table 36-3. USB Transfer Events
Transfer
TransactionDirection Type
CONTROL (bidirectional) Control
(1)(3)
Setup transaction → Data IN transactions → Status OUT transaction
Setup transaction → Data OUT transactions → Status IN transaction
Setup transaction → Status IN transaction
IN (device toward host)
Bulk IN
Data IN transaction → Data IN transactionInterrupt IN
Isochronous IN
(2)
OUT (host toward device)
Bulk OUT
Data OUT transaction → Data OUT transactionInterrupt OUT
Isochronous OUT
(2)
Control Read
Setup TX Data OUT TX Data OUT TX
Data Stage
Control Write
Setup Stage
Setup Stage
Setup TX
Setup TX
No Data
Control
Data IN TX Data IN TX
Status Stage
Status Stage
Status IN TX
Status OUT TX
Status IN TX
Data Stage
Setup Stage Status Stage