Texas Instruments OMAP5912 Reference Manual page 1594

USB OTG Controller
4.9 Onboard Transceiverless Connection Using OMAP5912
Transceiverless Link
302 Universal Serial Bus (USB)
The transceiverless link logic feature of the OMAP5912 USB signal
multiplexing enables connection of the OMAP5912 USB device controller to
an external, onboard USB host controller or connection of the OMAP5912
USB host controller, without the use of USB transceivers or associated
circuitry. When the transceiverless link logic is used, both of the USB
transceivers, the series resistors, pullup and pulldown resistors, VBUS
switching components, and USB connectors and cables that typically are used
between a USB host controller and the downstream USB device controller are
removed. The OMAP5912 transceiverless link logic feature does not support
OTG session request protocol or OTG host negotiation protocol, so it cannot
be used for a transceiverless OTG link.
The transceiverless link logic signaling system is not suitable for use across
a cable. It is intended only for use when the OMAP5912 device is used with
an external USB integrated circuit that is on the same board.
When using the transceiverless link logic, six of the external USB integrated
circuit pins that typically connect to a USB transceiver connect instead directly
to OMAP5912 device pins. Signaling on these pins use CMOS levels.
Transceiverless link logic can be used only with external devices that support
6-wire transceiver connectivity.
Figure 83 and Figure 84 show how transceiverless link logic can be compared
to a typical USB implementation. Figure 83 shows OMAP5912 being used as
a USB host controller, with the top portion of the diagram showing a
transceiver-based solution and the bottom portion showing a transceiverless
solution using the OMAP5912 transceiverless link logic. Figure 84 shows
OMAP5912 used as a USB device controller, with the top portion of the
diagram showing a transceiver-based solution and the bottom portion showing
a transceiverless solution using the OMAP5912 transceiverless link logic.
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