USB Reset

The USBHS sends a USB bus reset when the user writes a one to the Send USB Reset bit in the Host General Control register (USBHS_HSTCTRL.RESET). The USB Reset Sent Interrupt bit in the Host Global Interrupt Status register (USBHS_HSTISR.RSTI) is set when the USB reset has been sent. In this case, all pipes are disabled and de-allocated.

If the bus was previously in a “Suspend” state (the Start of Frame Generation Enable (USBHS_HSTCTRL.SOFE) bit is zero), the USBHS automatically switches to the “Resume” state, the Host Wakeup Interrupt (USBHS_HSTISR.HWUPI) bit is set and the USBHS_HSTCTRL.SOFE bit is set in order to generate SOFs or micro SOFs immediately after the USB reset.

At the end of the reset, the user should check the USBHS_SR.SPEED field to know the speed running according to the peripheral capability (LS.FS/HS).