Motorola USB08 - Manual (Page 72)

Designer Reference Manual USB08 Evaluation Board
72 Universal Serial Bus (USB) Interface MOTOROLA
Universal Serial Bus (USB) Interface
transaction, the function handleIN() is called. In the field bRequest of the
SetupBuffer, SET_ADDRESS is still contained as the current standard
request type. The function handleIN() now reacts by transferring the
device address from the buffer to the USB address register (UADDR).
The device is now turned into an ADDRESSED status. An exception
would be if the transmitted device address was zero again. This case
would mean an uncoupling of the device from the USB system.
With the completion of the IN transaction as a status stage, the control
transfer for the treatment of the standard device request
SET_ADDRESS is finished. The completion is noted in the SetupBuffer
by setting the flag REQUEST_COMPLETE.
4.6.3 Requesting Descriptors
Further in the process of enumeration, the host will request the
configuration of the device. For this purpose, descriptors which contain
information about the status and one or more possible configurations,
are made available by the device . The host loads these descriptors,
selects a suitable driver, and forces the device to take a certain
configuration. As a consequence, the device will be ready for use and
will be able to transfer data via the interrupt endpoints EP1 and EP2.
Sending descriptor information takes place during a standard device
request. The request is of the type GET_DESCRIPTOR and in principle
is handled the same way as that for the standard device request,
SET_ADDRESS, described above.
Bit 7 6 5 4 3 2 1 Bit 0
Read:
USBEN UADD6 UADD5 UADD4 UADD3 UADD2 UADD1 UADD0
Write:
Reset: 0 0 0 0 0 0 0 0
= Unimplemented
Figure 4-8. USB Address Register (UADDR)