Universal Serial Bus
M30240 Group
Rev.1.00 Sep 24, 2003 Page 317 of 360
Figure 3.30: Initializing USB Function Control Unit (4)
3.2.9 USB Control Transfers and SET-ADDRESS Request
Control transfers consist of the set-up stage, the data stage and the status stage. The data obtained
during the set-up stage determines which type of transfer (write, read, or data-less) occurs.
The SET_ADDRESS request is received in a read transfer from the host CPU in order to set the USB
address register (USBA). The USB Function Control unit uses this address for all later USB device
accesses.
Table 3.7 shows the composition of the SET_ADDRESS request and Figure 3.31 and Figure 3.32 show
the procedures for setting the device address. This routine should be placed in the Endpoint 0 interrupt
processing routine.
Table 3.7: SET_ADDRESS Request
0 byte
7 byte
bm Request Type
b Request wValue wIndex wlength
00000000B
SET_ADDRESS
(Code: 05
16
)
Device Address
00
Lower Position Upper Position
Selecting the USB ISO Control Register
000
USB ISO Control Register Address
USBISOC 0308
16
AUTO_FLUSH Bit
0 : Auto FIFO Flush disabled
1 : Auto FIFO Flush enabled
ISO_UPDATE Bit
0 : ISO update disabled
1 : ISO update enabled
Continued from previous page
00
b7 b0
0
USB Transmit Processing
When an Isochronous Transfer is used:
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