Texas Instruments OMAP5912 Reference Manual page 1528

USB OTG Controller
Figure 54. OTG Transceiver Status Read
4.2.5 Typical SRP and HNP Events
236 Universal Serial Bus (USB)
This section describes the typical sequence of events for SRP and HNP events
with the OMAP5912 OTG controller.
Careful system software design can optimize system performance by
managing interrupt source enables at both the OTG controller and at the OTG
transceiver. System software developers must carefully weigh the advantages
brought by disabling unneeded OTG transceiver interrupt sources versus the
performance cost associated with the I
transceiver interrupt sources.
Figure 55 shows the typical events that occur when OMAP5912 acts as an
OTG default-A dual-role device and the default-B device issues an SRP.
Figure 55 shows that the default-B device pulses its D+ pullup resistor. The
OMAP5912 OTG controller accepts D− pullup pulses as well as the D+ pullup
pulse shown as SRP data line.
Non-blocking OTG transceiver
status read via I 2 C
Get OTG transceiver status
information via I 2 C
(non-blocking)
Update OTG_CTRL[20:16] with
data received from OTG
transceiver
End of non-blocking OTG
transceiver status read via I 2 C
2
C activity to enable and disable the
SPRU761A