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UM10503
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© NXP B.V. 2015. All rights reserved.
User manual
Rev. 2.1 — 10 December 2015
697 of 1441
NXP Semiconductors
UM10503
Chapter 25: LPC43xx/LPC43Sxx USB0 Host/Device/OTG controller
After an endpoint is readied, the dTD will be copied into this queue head overlay area by
the device controller. Until a transfer is expired, software must not write the queue head
overlay area or the associated transfer descriptor. When the transfer is complete, the
device controller will write the results back to the original transfer descriptor and advance
the queue. See dTD for a description of the overlay fields.
25.9.1.4 Set-up buffer descriptor fields
The set-up buffer is dedicated storage for the 8-byte data that follows a set-up PID.
Remark:
Each endpoint has a TX and an RX dQH associated with it, and only the RX
queue head is used for receiving setup data packets.
25.9.2 Endpoint transfer descriptor (dTD)
The dTD describes to the device controller the location and quantity of data to be
sent/received for a given transfer. The DCD should not attempt to modify any field in an
active dTD except the Next Link Pointer, which should only be modified as described in
.
Table 506. Set-up buffer
Dword
Access
Bit
Name
Description
1
R/W
31:0
BUF0
Setup buffer 0
This buffer contains bytes 3 to 0 of an incoming setup
buffer packet and is written by the device controller to
be read by software.
2
R/W
31:0
BUF1
Setup buffer 1
This buffer contains bytes 7 to 4 of an incoming setup
buffer packet and is written by the device controller to
be read by software.
Table 507. Next dTD pointer
Access
Bit
Name
Description
RO
31:5
Next_link_pointer
Next link pointer
This field contains the physical memory address of the next
dTD to be processed. The field corresponds to memory
address signals [31:5], respectively.
4:1
-
reserved
0
T
Terminate
This bit indicates to the device controller when there are no
more valid entries in the queue.
1 - pointer is invalid
0 - Pointer is valid, i.e. pointer points to a valid transfer
element descriptor.