EFM32WG Datasheet, PDF (324/834 Pages) List of Unclassifed Manufacturers – The EFM32WG Wonder Gecko is the ideal choice for demanding 8-, 16-, and 32-bit energy sensitive applications.

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Figure 15.33. SRP Initiation by the Core When Acting as a B-Device
Device (OTG
FSM in b_idle st at e)
1. Program USB_GINTMSK
(unm ask OTGINT)
2. Read USB_GOTGCTL
Yes ( This indicat es t hat
VBUS is already being driven
and hence there is no need for
a SRP)
USB_GOTGCTL.
BSESVLD = 1 ?
Device Initialization
St eps. For m ore
inform at io,nsee
Device Initialization
section of this
chapt e.r
No
Set USB_GOTGCTL.
SESREQ = 1
No
Interrupt ?
Yes
No
Read
USB_GINTSTS
No
No
USB_GINTSTS.
OTGINT = 1?
Yes
Read
USB_GOTGINT
USB_GOTGINT.
SESREQSUCS
TSCHNG =1?
Yes
1. Read USB_GOTGCTL
2. Clear
USB_GOTGINT.SESREQSU
CSTSCHNG by writ ing
a1
Device
Transact ions
USB_GOTGCTL .
SESREQSCS
= 1?
Yes
Device Initialization
St eps. For m ore
inform at io,nsee
Device Initialization
section of this
chapt e. r
Note
The programming flow illustrated in Figure 15.33 (p. 324) is similar to OTG revision 1.3.
This is because the presence or absence of VBUS pulsing is transparent to the application.
15.4.6.2 OTG Revision 2.0 Host Negotiation Protocol
When the core is operating as A-device, the application must execute a GetStatus() operation to the B-
device with a frequency of THOST_REQ_POLL to determine the state of the host request flag in the
B-device. If the host request flag is set in B-device it must program the core to change its role within
THOST_REQ_SUSP.
Figure 15.34 (p. 325) shows the programming steps that need to be performed by A-device’s
application (core as A-device) in order to change its role to device. In Figure 15.34 (p. 325) , the A-
device performs a role change, becomes a B-device and then reverts back to host (A-device) mode of
operation.
2013-05-08 - Wonder Gecko Family - d0233_Rev0.50
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