USB on-the-go high-speed (OTG_HS) RM0033
1114/1381 RM0033 Rev 9
The end of periodic frame interrupt (GINTSTS/EOPF) is used to notify the application when
80%, 85%, 90% or 95% of the time frame interval elapsed depending on the periodic frame
interval field in the device configuration register (PFIVL bit in OTG_HS_DCFG).
This feature can be used to determine if all of the isochronous traffic for that frame is
complete.
30.8 OTG_HS low-power modes
Table 160 below defines the STM32 low power modes and their compatibility with the OTG.
The following bits and procedures reduce power consumption.
The power consumption of the OTG PHY is controlled by three bits in the general core
configuration register:
• PHY power down (GCCFG/PWRDWN)
This bit switches on/off the PHY full-speed transceiver module. It must be preliminarily
set to allow any USB operation.
• A-VBUS sensing enable (GCCFG/VBUSASEN)
This bit switches on/off the V
BUS
comparators associated with A-device operations. It
must be set when in A-device (USB host) mode and during HNP.
• B-VBUS sensing enable (GCCFG/VBUSASEN)
This bit switches on/off the V
BUS
comparators associated with B-device operations. It
must be set when in B-device (USB peripheral) mode and during HNP.
Power reduction techniques are available in the USB suspended state, when the USB
session is not yet valid or the device is disconnected.
• Stop PHY clock (STPPCLK bit in OTG_HS_PCGCCTL)
– When setting the stop PHY clock bit in the clock gating control register, most of the
clock domain internal to the OTG high-speed core is switched off by clock gating.
Table 160. Compatibility of STM32 low power modes with the OTG
Mode Description USB compatibility
Run MCU fully active
Required when USB not in
suspend state.
Sleep
USB suspend exit causes the device to exit Sleep mode. Peripheral
registers content is kept.
Available while USB is in
suspend state.
Stop
USB suspend exit causes the device to exit Stop mode. Peripheral
registers content is kept
(1)
.
Available while USB is in
suspend state.
Standby
Powered-down. The peripheral must be reinitialized after exiting
Standby mode.
Not compatible with USB
applications.
1. Within Stop mode there are different possible settings. Some restrictions may also exist, please refer to Section 4: Power
control (PWR) to understand which (if any) restrictions apply when using OTG.
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