Srp Dual Role Device - ST STM32L4x6 Reference Manual

RM0351
The HNP program model is described in detail in
model.
43.5.3

SRP dual role device

The SRP capable bit in the global USB configuration register (SRPCAP bit in
OTG_GUSBCFG) enables the OTG_FS core to switch off the generation of V
device to save power. Note that the A-device is always in charge of driving V
of the host or peripheral role of the OTG_FS.
the SRP A/B-device program model is described in detail in
programming
43.6 USB peripheral
This section gives the functional description of the OTG_FS in the USB peripheral mode.
The OTG_FS works as an USB peripheral in the following circumstances:
•
OTG B-Peripheral
–
•
OTG A-Peripheral
–
•
B-device
–
•
Peripheral only (see
–
Note: To build a bus-powered device implementation in case of the B-device or peripheral-only
configuration, an external regulator has to be added that generates the V
from V
BUS
model.
OTG B-device default state if B-side of USB cable is plugged in
OTG A-device state after the HNP switches the OTG_FS to its peripheral role
If the ID line is present, functional and connected to the B-side of the USB cable,
and the HNP-capable bit in the Global USB Configuration register (HNPCAP bit in
OTG_GUSBCFG) is cleared (see On-The-Go Rev1.3 par. 6.8.3).
Figure 495: USB_FS peripheral-only
The force device mode bit (FDMOD) in the
configuration register (OTG_GUSBCFG)
work as an USB peripheral-only (see On-The-Go Rev1.3 par. 6.8.3). In this case,
the ID line is ignored even if present on the USB connector.
.
DocID024597 Rev 3
USB on-the-go full-speed (OTG_FS)
Section 43.16: OTG_FS programming
Section 43.16: OTG_FS
connection)
Section 43.15.4: OTG USB
is set to 1, forcing the OTG_FS core to
for the A-
BUS
regardless
BUS
chip-supply
DD
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