UM10503
All information provided in this document is subject to legal disclaimers.
© NXP B.V. 2012. All rights reserved.
User manual
Rev. 1.3 — 6 July 2012
593 of 1269
NXP Semiconductors
UM10503
Chapter 24: LPC43xx USB1 Host/Device controller
24.6.2.1 Device mode
Table 460. USB Command register in device mode (USBCMD_D - address 0x4000 7140) bit description
Bit
Symbol
Value
Description
Reset
value
Access
0
RS
Run/Stop
0
R/W
0
Writing a 0 to this bit will cause a detach event.
1
Writing a one to this bit will cause the device controller to enable a pull-up
on USB_DP and initiate an attach event. This control bit is not directly
connected to the pull-up enable, as the pull-up will become disabled upon
transitioning into high-speed mode. Software should use this bit to prevent
an attach event before the device controller has been properly initialized.
1
RST
Controller reset.
Software uses this bit to reset the controller. This bit is set to zero by the
Host/Device Controller when the reset process is complete. Software
cannot terminate the reset process early by writing a zero to this register.
0
R/W
0
Set to 0 by hardware when the reset process is complete.
1
When software writes a one to this bit, the Device Controller resets its
internal pipelines, timers, counters, state machines etc. to their initial
values. Writing a one to this bit when the device is in the attached state is
not recommended, since the effect on an attached host is undefined. In
order to ensure that the device is not in an attached state before initiating a
device controller reset, all primed endpoints should be flushed and the
USBCMD Run/Stop bit should be set to 0.
3:2
-
Not used in device mode.
0
-
4
-
Not used in device mode.
0
-
5
-
Not used in device mode.
0
-
6
-
Not used in device mode. Writing a one to this bit when the device mode is
selected, will have undefined results.
-
-
7
-
-
Reserved. These bits should be set to 0.
-
-
9:8
-
-
Not used in Device mode.
-
-
10
-
Reserved.These bits should be set to 0.
0
-
11
-
-
Not used in Device mode.
-
12
-
Reserved.These bits should be set to 0.
0
-
13
SUTW
Setup trip wire
During handling a setup packet, this bit is used as a semaphore to ensure
that the setup data payload of 8 bytes is extracted from a QH by the DCD
without being corrupted. If the setup lockout mode is off (see USBMODE
register) then there exists a hazard when new setup data arrives while the
DCD is copying the setup data payload from the QH for a previous setup
packet. This bit is set and cleared by software and will be cleared by
hardware when a hazard exists. (See
).
0
R/W
14
ATDTW
Add dTD trip wire
This bit is used as a semaphore to ensure the to proper addition of a new
dTD to an active (primed) endpoint’s linked list. This bit is set and cleared
by software during the process of adding a new dTD. See also
.
This bit shall also be cleared by hardware when its state machine is hazard
region for which adding a dTD to a primed endpoint may go unrecognized.
0
R/W