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78 otg device control register (devctl), Section 4.78 – Texas Instruments TMS320DM357 User Manual

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4.78 OTG Device Control Register (DEVCTL)

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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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