UM0463

The USB state machine of the control endpoint

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Figure 2.

State machine execution

In summary, the callback function USER_USB_Setup() opens the door for the user code to

parse the class specific or vendor specific requests or the Get Descriptor requests for

nonconstant descriptors. The callback functions USER_USB_CopydataIN() and

USER_USB_CopydataOUT() transfer data for those requests. The callback functions

USER_USB_Status_In() and USER_USB_Status_Out() inform the user code that the

process of a SETUP request is finished.

Note:

For a complete list of callback functions please refer to Section 7.3.

The library checks the data transfer

direction and the data transfer length.

In_Data

Out_Data

Wait_Status_In

Wait_Status_Out

The library parses the request and passes non-

standard

request

to

USER_Setup().

The

variable vUSB_DataToSend and vUSB_length

are set according to the request.

One data packet

is sent.

In_Data

The library copies the next data

packet to the DMA buffer if the

data buffer is continued. Otherwise,

USER_CopydataIN() is called.

Data IN stage

One data packet is received

and USER_CopydataOUT()

is called.

Out_Data

Wait_Status_In

Data OUT stage

USER_Status_Out()

is

called

after the device acknowledges

the status OUT stage.

USER_Status_In() is called after

the device acknowledges the

status OUT stage.

Wait_Setup

Wait_Setup

A SETUP packet is received and is

copied to sUSB_vSetup structure.