CHAPTER 12 USB FUNCTION CONTROLLER (USBF)
Preliminary User’s Manual U19014EJ1V0UD
277
(2) Processing
The processing of an automatic request in the Default state, Addressed state, and Configured state is
described below.
Remark
Default state: State in which an operation is performed with the Default address
Addressed state: State after an address has been allocated
Configured state: State after SET_CONFIGURATION wValue = 1 has been correctly received
(a) CLEAR_FEATURE() request
A STALL response is made in the status stage if the CLEAR_FEATURE() request cannot be cleared, if
FEATURE does not exist, or if the target is an interface or an endpoint that does not exist. A STALL
response is also made if the wLength value is other than 0.
•
Default state:
The correct response is made when the CLEAR_FEATURE() request has been
received only if the target is a device or a request for Endpoint0; otherwise a STALL
response is made in the status stage.
•
Addressed state: The correct response is made when the CLEAR_FEATURE() request has been
received only if the target is a device or a request for Endpoint0; otherwise a STALL
response is made in the status stage.
•
Configured state: The correct response is made when the CLEAR_FEATURE() request has been
received only if the target is a device or a request for an endpoint that exists;
otherwise a STALL response is made in the status stage.
When the CLEAR_FEATURE() request has been correctly processed, the corresponding bit of the UF0
CLR request register (UF0CLR) is set to 1, the EnHALT bit of the UF0 EPn status register L (UF0EnSL) is
cleared to 0, and an interrupt is issued (n = 0 to 2). If the CLEAR_FEATURE() request is received when
the subject is an endpoint, the toggle bit (that controls switching between DATA0 and DATA1) of the
corresponding endpoint is always re-set to DATA0.
(b) GET_CONFIGURATION() request
A STALL response is made in the data stage if any of wValue, wIndex, or wLength is other than the values
shown in Table 12-3.
•
Default state:
The value stored in the UF0 configuration register (UF0CNF) is returned when the
GET_CONFIGURATION() request has been received.
•
Addressed
state:
The value stored in the UF0CNF register is returned when the
GET_CONFIGURATION() request has been received.
•
Configured
state:
The value stored in the UF0CNF register is returned when the
GET_CONFIGURATION() request has been received.
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