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6437E–ATARM–23-Apr-13
SAM9M11
Notes:
1. Control transfer must use endpoints with one bank and can be aborted using a stall handshake.
2. Isochronous transfers must use endpoints configured with two or three banks.
An endpoint handles all transactions related to the type of transfer for which it has been
configured.
40.5.4
USB V2.0 High Speed BUS Transactions
Each transfer results in one or more transactions over the USB bus.
There are five kinds of transactions flowing across the bus in packets:
1.
Setup Transaction
2.
Data IN Transaction
3.
Data OUT Transaction
4.
Status IN Transaction
5.
Status OUT Transaction
Figure 40-4. Control Read and Write Sequences
A status IN or OUT transaction is identical to a data IN or OUT transaction.
40.5.5
Endpoint Configuration
The endpoint 0 is always a control endpoint, it must be programmed and active in order to be
enabled when the End Of Reset interrupt occurs.
OUT
(host toward device)
Bulk OUT Transfer
Data OUT transaction
→ Data OUT transaction
Interrupt OUT Transfer
Data OUT transaction
→ Data OUT transaction
Isochronous OUT Transfer
(2) Data OUT transaction
→ Data OUT transaction
Table 40-3.
USB Transfer Events (Continued)
CONTROL
(bidirectional)
Control Transfers (1)
Setup transaction
→ Data IN transactions →Status OUT transaction
Setup transaction
→ Data OUT transactions →Status IN transaction
Setup transaction
→ Status IN transaction
Control Write
Setup TX
Data OUT TX
Data Stage
Control Read
Setup Stage
Setup TX
No Data
Control
Data IN TX
Status Stage
Status IN TX
Status OUT TX
Status IN TX
Data Stage
Setup Stage
Status Stage