Universal Serial Bus OTG Controller
UG0331 User Guide Revision 15.0
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10.3.8.1 DEV_CTRL_REG Bit Definitions
10.3.8.2 Encoding of VBus Level
Table 241 •
DEV_CTRL_REG (0x40043060)
Bit
Number
Name
Reset Value Function
7
B-Device
1
Indicates whether the USB controller is operating as the A device or the B
device.
0: A device
1: B device
Only valid while a session is in progress. To determine the role when no
session is in progress, set the session bit and read this bit.
If the core is in Force_Host mode (a session has been started with
TESTMODE_REG.bit[7] = 1), this bit indicates the state of the
FAB_HOSTDISCON input signal.
6
FSDev
0
This read-only bit is set when a full speed or high speed device has been
detected being connected to the port. High speed devices are distinguished
from full speed by checking for high speed chirps when the device is reset.
Only valid in Host mode.
5
LSDev
0
This read-only bit is set when a low speed device has been detected being
connected to the port. Only valid in Host mode.
[4:3]
Vbus[1:0]
0
These read-only bits encode the current VBus level as given in
2
Host Mode 0
This read-only bit is set when the USB controller is acting as a host.
1
Host Req
0
When set, the USB controller initiates the host negotiation when Suspend
mode is entered It is cleared when host negotiation is completed. B device
only).
0
Session
0
When operating as an A device, this bit is set or cleared by the Cortex-M3
processor (or fabric master) to start or end a session. When operating as a B
device, this bit is set/cleared by the USB controller when a session starts/ends.
It is also set by the Cortex-M3 processor (or fabric master) to initiate the
session request protocol. When the USB controller is in Suspend mode, the bit
may be cleared by the Cortex-M3 processor (or fabric master) to perform a
software disconnect.
Clearing this bit when the core is not suspended will result in undefined
behavior.
Table 242 •
Encoding of VBus Level
D4
D3
Meaning
0
0
Below session end
0
1
Above session end, below Avalid
1
0
Above Avalid, below VBus valid
1
1
Above VBus valid