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UM10375
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© NXP B.V. 2011. All rights reserved.
User manual
Rev. 3 — 14 June 2011
158 of 368
NXP Semiconductors
UM10375
Chapter 10: LPC13xx USB device controller
10.11.8 Get Device Status (Command: 0xFE, Data: read 1 byte)
The Get Device Status command returns the Device Status Register. Reading the device
status returns 1 byte of data. The bit field definition is same as the Set Device Status
Register as shown in
.
Remark:
To ensure correct operation, the DEV_STAT bit of USBDevIntSt must be cleared
before executing the Get Device Status command.
2
SUS
Suspend: The Suspend bit represents the current suspend state.
When the device is suspended (SUS = 1) and the CPU writes a 0
into it, the device will generate a remote wake-up. This will only
happen when the device is connected (CON = 1). When the
device is not connected or not suspended, writing a 0 has no
effect. Writing a 1 to this bit has no effect.
0
0
This bit is reset to 0 on any activity.
1
This bit is set to 1 when the device hasn’t seen any activity on its
upstream port for more than 3 ms.
3
SUS_CH
Suspend (SUS) bit change indicator. The SUS bit can toggle
because:
•
The device goes into the suspended state.
•
The device is disconnected.
•
The device receives resume signalling on its upstream port.
This bit is cleared when read.
0
0
SUS bit not changed.
1
SUS bit changed. At the same time a DEV_STAT interrupt is
generated.
4
RST
Bus Reset bit. On a bus reset, the device will automatically go to
the default state. In the default state:
•
Device is unconfigured.
•
Will respond to address 0.
•
Control endpoint will be in the Stalled state.
•
Data toggling is reset for all endpoints.
•
All buffers are cleared.
•
There is no change to the endpoint interrupt status.
•
DEV_STAT interrupt is generated.
Note: Bus resets are ignored when the device is not connected
(CON=0).
0
0
This bit is cleared when read.
1
This bit is set when the device receives a bus reset. A DEV_STAT
interrupt is generated.
7:5
-
Reserved, user software should not write ones to reserved bits.
The value read from a reserved bit is not defined.
NA
Table 181. Set Device Status command description
Bit
Symbol
Value
Description
Reset
value