Datasheet

506
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
35.5.1.3 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 trans-
fer 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.
Table 35-3. USB Transfer Events
Control Transfers
(1) (3)
• Setup transaction > Data IN transactions > Status
OUT transaction
• Setup transaction > Data OUT transactions > Status
IN transaction
• Setup transaction > Status IN transaction
Interrupt IN Transfer
(device toward host)
• Data IN transaction > Data IN transaction
Interrupt OUT Transfer
(host toward device)
• Data OUT transaction > Data OUT transaction
Isochronous IN Transfer
(2)
(device toward host)
• Data IN transaction > Data IN transaction
Isochronous OUT Transfer
(2)
(host toward device)
• Data OUT transaction > Data OUT transaction
Bulk IN Transfer
(device toward host)
• Data IN transaction > Data IN transaction
Bulk OUT Transfer
(host toward device)
• Data OUT transaction > Data OUT transaction