64.6.4 USB Transfer Event Definitions
A transfer is composed of one or several transactions as shown in the table below.
Transfer | Transaction | |
---|---|---|
Direction | Type | |
CONTROL (bidirectional) | Control Transfer (1) |
|
IN (device toward host) | Bulk IN Transfer |
|
Interrupt IN Transfer |
|
|
Isochronous IN Transfer (2) |
|
|
OUT (host toward device) | Bulk OUT Transfer |
|
Interrupt OUT Transfer |
|
|
Isochronous OUT Transfer (2) |
|
Note:
- Control transfer must use endpoints with one bank and can be aborted using a stall handshake.
- 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.
Endpoint # | Mnemonic | Nb Banks | DMA | High Bandwidth | Max. Endpoint Size | Endpoint Type |
---|---|---|---|---|---|---|
0 | EPT_0 | 1 | N | N | 64 | Control |
1 | EPT_1 | 2 | Y | N | 1024 | Ctrl/Bulk/Iso(1)/Interrupt |
2 | EPT_2 | 2 | Y | N | 1024 | Ctrl/Bulk/Iso(1)/Interrupt |
3 | EPT_3 | 3 | Y | Y | 1024 | Ctrl/Bulk/Iso(1)/Interrupt |
4 | EPT_4 | 3 | Y | Y | 1024 | Ctrl/Bulk/Iso(1)/Interrupt |
5 | EPT_5 | 3 | Y | Y | 1024 | Ctrl/Bulk/Iso(1)/Interrupt |
6 | EPT_6 | 3 | Y | Y | 1024 | Ctrl/Bulk/Iso(1)/Interrupt |
Note:
- In Isochronous (Iso) mode, it is preferable that the high bandwidth capability is available.
The size of the internal DPRAM is 16448 bytes, covering the memory need for the seven endpoints, hence enabling static allocation of the memory for all endpoints.
Suspend and resume are automatically detected by the UDPHS device, which notifies the processor by raising an interrupt.