Usb Functional Description On Host Mode; Srp-Capable Host; Figure 374. Usb Host-Only Connection - ST STM32F207 Series Reference Manual

USB on-the-go high-speed (OTG_HS)
30.6

USB functional description on host mode

This section gives the functional description of the OTG_HS in the USB host mode. The
OTG_HS works as a USB host in the following circumstances:
•
OTG A-host
OTG A-device default state when the A-side of the USB cable is plugged in
•
OTG B-host
OTG B-device after HNP switching to the host role
•
A-device
If the ID line is present, functional and connected to the A-side of the USB cable, and
the HNP-capable bit is cleared in the Global USB Configuration register (HNPCAP bit
in OTG_HS_GUSBCFG). Integrated pull-down resistors are automatically set on the
DP/DM lines.
•
Host only
The force host mode bit in the global USB configuration register (FHMOD bit in
OTG_HS_GUSBCFG) forces the OTG_HS core to operate in USB host-only mode. In
this case, the ID line is ignored even if it is available on the USB connector. Integrated
pull-down resistors are automatically set on the OTG_HS_FS_DP/OTG_HS_FS_DM
lines.
Note: On-chip 5 V V
switch (if a 5 V supply is available on the application board) must be added externally to
drive the 5 V V
is required for the OTG A-host, A-device and host-only configurations.
The V
BUS
operations while the charge pump overcurrent output can be input to any GPIO pin
configured to generate port interrupts. The overcurrent ISR must promptly disable the V
generation.
30.6.1

SRP-capable host

SRP support is available through the SRP capable bit in the global USB configuration
register (SRPCAP bit in OTG_HS_GUSBCFG). When the SRP feature is enabled, the host
can save power by switching off the V
1108/1381
(Figure 352: USB host-only
generation is not supported. As a result, a charge pump or a basic power
BUS
line. The external charge pump can be driven by any GPIO output. This
BUS
input ensures that valid V

Figure 374. USB host-only connection

V
GPIO + IRQ
OSC_IN
OSC_OUT
connection).
levels are supplied by the charge pump during USB
BUS
DD
5 V
EN
STMPS2141STR
GPIO
Current-limited
power distribution
Overcurrent
switch
power while the USB session is suspended. The
BUS
RM0033 Rev 9
5 V Pwr
(2)
VBUS
DM
DP
V
SS
RM0033
BUS
MSv36915V2