Function of USBx_VBUS pins in the imx8mp

[diegoperez]

Hi,

I am designing the USBs for imx8mp using only 2.0 phy D+ and D-, because I do not need usb 3.0.

One USB is connected to 2.0 hub in the pcb, so always will be a host. The other is used as micro USB otg connector that can be host or device.

I have some doubts about USBx_VBUS pins:

What is the function of USB1_VBUS (ball A11) and USB2_VBUS (ball D12)?

In the case of USB HUB connection: could be this pin floating?

In the case of USB micro OTG connector: this pin needs to be connected to 5V of the USB OTG connector?

[AldoG]

Hello,

For a USB2.0 Host interface, you can just remove the USB3.0 TX/RX signals, just keep traditional USB2.0 signals.

USB_VBUS is not need to connect to I.MX8M Plus, as it's forced to be Host mode by software. ID is also not need for Host interface.

You may refer to the board schematic for this, USB3.0 HOST page 7.

Best regards,
Aldo.

[daharingwitekio]

What about the USB peripheral use case? I have a similar design with a Micro USB port connected with the phy D+ and D- lines and only need it to ever operate in peripheral mode. Do I need VBUS at all for this use case or will it affect the systems choice of Host vs Peripheral?

Followup question, regarding UUU/MFGTools and the USB, is there any requirement that the USB used to flash operate as an OTG as opposed to a peripheral only USB port?

[diegoperez]

Hi,

@AldoG USB_VBUS is needed if I implement a USB OTG that can be host/device?

Thanks and BR.