RM0090: Reference manual - STMicroelectronics

USB on-the-go high-speed (OTG_HS) RM0090
In Powered state, the OTG_HS expects a reset from the host. No other USB operations are
possible. When a reset is received, the reset detected interrupt (USBRST in
OTG_HS_GINTSTS) is generated. When the reset is complete, the enumeration done
interrupt (ENUMDNE bit in OTG_HS_GINTSTS) is generated and the OTG_HS enters the
Default state.
Soft disconnect
The Powered state can be exited by software by using the soft disconnect feature. The DP
pull-up resistor is removed by setting the Soft disconnect bit in the device control register
(SDIS bit in OTG_HS_DCTL), thus generating a device disconnect detection interrupt on the
host side even though the USB cable was not really unplugged from the host port.
Default state
In Default state the OTG_HS expects to receive a SET_ADDRESS command from the host.
No other USB operations are possible. When a valid SET_ADDRESS command is decoded
on the USB, the application writes the corresponding number into the device address field in
the device configuration register (DAD bit in OTG_HS_DCFG). The OTG_HS then enters
the address state and is ready to answer host transactions at the configured USB address.
Suspended state
The OTG_HS peripheral constantly monitors the USB activity. When the USB remains idle
for 3 ms, the early suspend interrupt (ESUSP bit in OTG_HS_GINTSTS) is issued. It is
confirmed 3 ms later, if appropriate, by generating a suspend interrupt (USBSUSP bit in
OTG_HS_GINTSTS). The device suspend bit is then automatically set in the device status
register (SUSPSTS bit in OTG_HS_DSTS) and the OTG_HS enters the Suspended state.
The device can also exit from the Suspended state by itself. In this case the application sets
the remote wakeup signaling bit in the device control register (RWUSIG bit in
OTG_HS_DCTL) and clears it after 1 to 15 ms.
When a resume signaling is detected from the host, the resume interrupt (WKUPINT bit in
OTG_HS_GINTSTS) is generated and the device suspend bit is automatically cleared.
31.5.3 Peripheral endpoints
The OTG_HS core instantiates the following USB endpoints:
● Control endpoint 0
This endpoint is bidirectional and handles control messages only.
It has a separate set of registers to handle IN and OUT transactions, as well as
dedicated control (OTG_HS_DIEPCTL0/OTG_HS_DOEPCTL0), transfer configuration
(OTG_HS_DIEPTSIZ0/OTG_HS_DIEPTSIZ0), and status-interrupt
1161/1416 Doc ID 018909 Rev 3