User manual

...the world's most energy friendly microcontrollers
2012-04-24 - Giant Gecko Family - d0053_Rev0.96 325
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Figure 15.32. SRP Detection by Core When Operating as A-device
Read USB_GINTSTS
No
Yes
Interrupt?
Yes
No
Host Transactions
If host’s application decides to
turn on VBUS voluntarily,
then the application need
not wait for SRP from
device.
Note: If MODEMIS interrupt
is detected during this
process, it means that the
connector has been
plugged out or
interchanged. This can be
confirmed by reading
Host mode (PHY
not driving VBUS)
Program USB_GINTMSK.
(Unmask OTGINT, MODEMIS,
SESSREQINT)
GINTSTS.
SESSREQINT = 1 ?
USB_GINTSTS.CONIDSTSCHNG
Host Initialization Steps. Refer to the Host
Initialization section of this chapter for
more inform ation.
(In this step the OTG FSM is in a_host
state.)
Figure 15.33 (p. 326) illustrates the steps that need to be performed by B-device’s application (core
as B-device) in order to establishing a connection with A-device by signaling a SRP.