38.6.1.3 MCU Power Modes

USB Suspend Mode

In Peripheral mode, the Suspend Interrupt bit in the Device Global Interrupt Status register (USBHS_DEVISR.SUSP) indicates that the USB line is in Suspend mode. In this case, the transceiver is automatically set in Suspend mode to reduce consumption.

Clock Frozen

The USBHS can be frozen when the USB line is in the Suspend mode, by writing a one to the USBHS_CTRL.FRZCLK bit, which reduces power consumption.

In this case, it is still possible to access the following:

• USBHS_CTRL.FRZCLK, USBHS_CTRL.USBE and USBHS_DEVCTRL.LS bits

Moreover, when USBHS_CTRL.FRZCLK = 1, only the asynchronous interrupt sources can trigger the USB interrupt:

• Wakeup Interrupt (USBHS_DEVISR.WAKEUP)
• Host Wakeup Interrupt (USBHS_HSTISR.HWUPI)