ST STM32F446 Series User Manual

RM0390 Rev 4 1087/1328
RM0390 USB on-the-go full-speed/high-speed (OTG_FS/OTG_HS)
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31.5.2 HNP dual role device
The HNP capable bit in the Global USB configuration register (HNPCAP bit in OTG_
GUSBCFG) enables the OTG_FS/OTG_HS core to dynamically change its role from A-host
to A-peripheral and vice-versa, or from B-Peripheral to B-host and vice-versa according to
the host negotiation protocol (HNP). The current device status can be read by the combined
values of the connector ID status bit in the Global OTG control and status register (CIDSTS
bit in OTG_GOTGCTL) and the current mode of operation bit in the global interrupt and
status register (CMOD bit in OTG_GINTSTS).
The HNP program model is described in detail in Section 31.16: OTG_FS/OTG_HS
programming model.
31.5.3 SRP dual role device
The SRP capable bit in the global USB configuration register (SRPCAP bit in
OTG_GUSBCFG) enables the OTG_FS/OTG_HS core to switch off the generation of V
BUS
for the A-device to save power. Note that the A-device is always in charge of driving V
BUS
regardless of the host or peripheral role of the OTG_FS/OTG_HS.
The SRP A/B-device program model is described in detail in Section 31.16:
OTG_FS/OTG_HS programming model.
31.6 USB peripheral
This section gives the functional description of the OTG_FS/OTG_HS in the USB peripheral
mode. The OTG_FS/OTG_HS works as an USB peripheral in the following circumstances:
• OTG B-Peripheral
– OTG B-device default state if B-side of USB cable is plugged in
• OTG A-Peripheral
– OTG A-device state after the HNP switches the OTG_FS/OTG_HS to its
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_GUSBCFG) is cleared.
• Peripheral only (see Figure 403: USB_FS peripheral-only connection)
– The force device mode bit (FDMOD) in the
Section 31.15.4: OTG USB
configuration register (OTG_GUSBCFG) is set to 1, forcing the OTG_FS/OTG_HS
core to work as an USB peripheral-only. In this case, the ID line is ignored even if
it is present on the USB connector.
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 necessary power-
supply from V
BUS
.

ST STM32F446 Series Specifications

General

Brand	ST
Model	STM32F446 Series
Category	Microcontrollers
Language	English