Datasheet

433
SAM7X Series [DATASHEET]
6120K–ATARM–11-Feb-14
34.5.1.2 USB Bus Transactions
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
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