Texas Instruments OMAP5912 Reference Manual page 1566

USB OTG Controller
4.7 Host Controller Connectivity With USB Transceivers
USB Host Connections Using the OMAP5912 Integrated USB Transceiver
274 Universal Serial Bus (USB)
See Table 74.
HMC_MODE must be set to a value that provides OTG functionality on USB
Alternate Pin group 2 (see Table 73). OTG_SYSCON_1.USB1_TRX_MODE
must be set to 3 to allow proper operation of the 6-wire USB transceiver.
To provide a robust USB solution, a system that provides a USB host controller
must implement certain features. These features include a type-A receptacle,
power on the VBUS signal (can be switched or unswitched power), transient
suppression, pulldown resistors, and USB-compatible downstream port
transceiver.
Because OMAP5912 does not provide a pin that connects to the USB host
controller port power control registers, some other mechanism must be used
if VBUS switching is required. Similarly, OMAP5912 does not provide any pins
that connect to the USB host controller overcurrent status bits, so some other
mechanism must be used if overcurrent sensing is required.
Some USB transceivers implement a 6-wire connection to the host controller,
whereas others require only 4 wires or 3 wires. The OMAP5912 device must
be properly configured to support the signaling required by the attached
transceiver.
It is possible to use OTG transceiver connectivity to provide a USB host-only
port. The OTG transceiver meets all of the requirements of a USB upstream
transceiver with the exception of VBUS current sourcing. OTG transceiver
VBUS current is typically limited to a maximum value that is lower than the
minimum required by the USB specification for a Type-A receptacle. Systems
that use an OTG transceiver to control a host-only Type-A receptacle must
provide some VBUS source that is capable of meeting USB specification
current requirements. Systems that implement a standard Type-A USB
receptacle and use an OTG transceiver must ground the OTG transceiver ID
input. If the OTG transceiver is used to monitor VBUS for a standard Type-A
USB receptacle, a series resistor is recommended between the OTG
transceiver VBUS pin and the connector so that the OTG transceiver cannot
drive any significant current onto VBUS.
The OMAP5912 integrated USB transceiver can provide connectivity for a
host-controller port. Figure 66 shows a way to connect the integrated USB
transceiver as a host-only port.
SPRU761A