UM10462 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2016. All rights reserved.
User manual Rev. 5.5 — 21 December 2016 227 of 523
NXP Semiconductors
UM10462
Chapter 11: LPC11U3x/2x/1x USB2.0 device controller
16 DCON Device status - connect.
The connect bit must be set by SW to indicate that the device
must signal a connect. The pull-up resistor on USB_DP will be
enabled when this bit is set and the VbusDebounced bit is one.
0RW
17 DSUS Device status - suspend.
The suspend bit indicates the current suspend state. It is set to
1 when the device hasn’t seen any activity on its upstream port
for more than 3 milliseconds. It is reset to 0 on any activity.
When the device is suspended (Suspend bit DSUS = 1) and the
software writes a 0 to it, the device will generate a remote
wake-up. This will only happen when the device is connected
(Connect bit = 1). When the device is not connected or not
suspended, a writing a 0 has no effect. Writing a 1 never has an
effect.
0RW
18 - Reserved. 0 RO
19 LPM_SUS Device status - LPM Suspend.
This bit represents the current LPM suspend state. It is set to 1
by HW when the device has acknowledged the LPM request
from the USB host and the Token Retry Time of 10 s has
elapsed. When the device is in the LPM suspended state (LPM
suspend bit = 1) and the software writes a zero to this bit, the
device will generate a remote walk-up. Software can only write
a zero to this bit when the LPM_REWP bit is set to 1. HW resets
this bit when it receives a host initiated resume. HW only
updates the LPM_SUS bit when the LPM_SUPP bit is equal to
one.
0RW
20 LPM_REWP LPM Remote Wake-up Enabled by USB host.
HW sets this bit to one when the bRemoteWake bit in the LPM
extended token is set to 1. HW will reset this bit to 0 when it
receives the host initiated LPM resume, when a remote
wake-up is sent by the device or when a USB bus reset is
received. Software can use this bit to check if the remote
wake-up feature is enabled by the host for the LPM transaction.
0RO
23:20 - Reserved. 0 RO
24 DCON_C Device status - connect change.
The Connect Change bit is set when the device’s pull-up
resistor is disconnected because VBus disappeared. The bit is
reset by writing a one to it.
0RWC
25 DSUS_C Device status - suspend change.
The suspend change bit is set to 1 when the suspend bit
toggles. The suspend bit can toggle because:
- The device goes in the suspended state
- The device is disconnected
- The device receives resume signaling on its upstream port.
The bit is reset by writing a one to it.
0RWC
26 DRES_C Device status - reset change.
This bit is set when the device received a bus reset. On a bus
reset the device will automatically go to the default state
(unconfigured and responding to address 0). The bit is reset by
writing a one to it.
0RWC
Table 214. USB Device Command/Status register (DEVCMDSTAT, address 0x4008 0000) bit description
Bit Symbol Value Description Reset
value
Access
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