Datasheet

441
6120F–ATARM–03-Oct-06
AT91SAM7X512/256/128 Preliminary
1. Setup Transaction
2. Data IN Transaction
3. Data OUT Transaction
34.5.1.3 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 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.
Table 34-3. 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