Srp Dual-Role Device; Usb Functional Description In Peripheral Mode; Srp-Capable Peripheral - ST STM32F205 series Reference Manual

USB on-the-go high-speed (OTG_HS)
combination of the Connector ID Status bit in the Global OTG control and status register
(CIDSTS bit in OTG_HS_GOTGCTL) and the current mode of operation bit in the global
interrupt and status register (CMOD bit in OTG_HS_GINTSTS).
The HNP programming model is described in detail in
programming
30.4.3

SRP dual-role device

The SRP capable bit in the global USB configuration register (SRPCAP bit in
OTG_HS_GUSBCFG) configures the OTG_HS core to switch V
order to save power. The A-device is always in charge of driving V
OTG_HS role (host or peripheral). The SRP A/B-device program model is described in
detail in Section 30.13: OTG_HS programming
30.5

USB functional description in peripheral mode

The OTG_HS operates as an USB peripheral in the following circumstances:
•
OTG B-device
OTG B-device default state if the B-side of USB cable is plugged in
•
OTG A-device
OTG A-device state after the HNP switches the OTG_HS to peripheral role
•
B-Device
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_HS_GUSBCFG) is cleared (see On-The-Go specification Revision 1.3 section
6.8.3).
•
Peripheral only (see
The force peripheral mode bit in the Global USB configuration register (FDMOD in
OTG_HS_GUSBCFG) is set to 1, forcing the OTG_HS core to operate in USB
peripheral-only mode (see On-The-Go specification Revision 1.3 section 6.8.3). In this
case, the ID line is ignored even if it is available on the USB connector.
Note: To build a bus-powered device architecture in the B-Device or peripheral-only configuration,
an external regulator must be added to generate the V
30.5.1

SRP-capable peripheral

The SRP capable bit in the Global USB configuration register (SRPCAP bit in
OTG_HS_GUSBCFG) configures the OTG_HS to support the session request protocol
(SRP). As a result, it allows the remote A-device to save power by switching V
the USB session is suspended.
The SRP peripheral mode program model is described in detail in
session request
1102/1378
model.
Figure 351: USB peripheral-only
protocol.
RM0033 Rev 8
Section 30.13: OTG_HS
off for the A-device in
BUS
BUS
model.
connection)
supply voltage from V
DD
Section : B-device
RM0033
regardless of the
.
BUS
off when
BUS