Universal Serial Bus Controller User's Guide

4.78 OTG Device Control Register (DEVCTL)
www.ti.com Registers
The OTG Device Control Register (DEVCTL) is shown in Figure 93 and described in Table 94 .
Figure 93. OTG Device Control Register (DEVCTL)
7 6 5 4 3 2 1 0
BDEVICE FSDEV LSDEV VBUS HOSTMODE HOSTREQ SESSION
R-0 R-0 R-0 R-0 R-0 R/W-0 R/W-0
LEGEND: R/W = Read/Write; R = Read only; - n = value after reset
Table 94. OTG Device Control Register (DEVCTL) Field Descriptions
Bit Field Value Description
7 BDEVICE This read-only bit 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.
6 FSDEV 0-1 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 0-1 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 0-3h These read-only bits encode the current VBus level as follows:
0 Below Session End
1h Above Session End, below AValid
2h Above AValid, below VBusValid
3h Above VBusValid
2 HOSTMODE 0-1 This read-only bit is set when the USB controller is acting as a Host.
1 HOSTREQ 0-1 When set, the USB controller will initiate the Host Negotiation when Suspend mode is entered. It is
cleared when Host Negotiation is completed. ('B' device only)
0 SESSION 0-1 When operating as an 'A' device, you must set or clear this bit 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.
You must also set this bit to initiate the Session Request Protocol. When the USB controller is in
Suspend mode, you may clear the bit to perform a software disconnect.
A special software routine is required to perform SRP. Details will be made available in a later
document version.
SPRUGH3 – November 2008 Universal Serial Bus (USB) Controller 137
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