Srp Dual Role Device; Usb Peripheral - ST STM32F40 Series Reference Manual

USB on-the-go full-speed (OTG_FS)
The HNP program model is described in detail in
model.
30.4.3

SRP dual role device

The SRP capable bit in the global USB configuration register (SRPCAP bit in
OTG_FS_GUSBCFG) enables the OTG_FS core to switch off the generation of V
A-device to save power. Note that the A-device is always in charge of driving V
regardless of the host or peripheral role of the OTG_FS.
the SRP A/B-device program model is described in detail in
programming
30.5

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
The V
BUS
NOVBUSSENS bit in the OTG_FS_GCCFG register. In this case the V
internally to be always at V
1027/1422
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_FS_GUSBCFG) is cleared (see On-The-Go Rev1.3 par. 6.8.3).
Figure 359: USB peripheral-only
The force device mode bit in the Global USB configuration register (FDMOD in
OTG_FS_GUSBCFG) is set to 1, forcing the OTG_FS core to work as a 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.
.
pin can be freed by disabling the V
BUS
Doc ID 018909 Rev 4
Section 30.17: OTG_FS programming
sensing option. This is done by setting the
BUS
valid level (5 V).
BUS
Section 30.17: OTG_FS
connection)
chip-supply
DD
is considered
BUS
RM0090
for the
BUS