i.MX Processors中的主题 i.mx 8M Mini: Required USB pins to provision processor?

i.mx 8M Mini: Required USB pins to provision processor?

adevries — Fri, 12 Mar 2021 01:27:43 GMT

Hello,

I am working on a design that uses the i.MX 8M Mini application processor. I know this processor is capable of USB OTG mode, which uses 7 pins (VBUS, DP, DN, ID, GND, OTG_OC, and OTG_PWR). However, if I have no need for OTG mode, and I only ever need my board to act as a USB peripheral, is it acceptable to not connect pins ID, OTG_OC, and OTG_PWR? If I only route VBUS, DP, DN, and GND out to a USB connector, will I still be able to use the USB port to initially provision the processor and load the OS image on the e.MMC?

Thanks

Re: i.mx 8M Mini: Required USB pins to provision processor?

Yuri — Fri, 12 Mar 2021 04:31:15 GMT

@adevries
Hello,

Generally - from hardware point of view - it is possible
to use Your approach, assuming the ID pin is left floating
(not grounded).

Nevertheless, regarding software, please use Chapter 19 (Porting
USB) of the i.MX Porting Guide and section 4.9 (USB)of the i.MX Linux
Reference Manual.

https://www.nxp.com/design/software/embedded-software/i-mx-software/embedded-linux-for-i-mx-applications-processors:IMXLINUX

Regards,
Yuri.

Re: i.mx 8M Mini: Required USB pins to provision processor?

adevries — Fri, 12 Mar 2021 16:00:42 GMT

Hi Yuri,

Thanks for the information. So when the processor is in serial download mode and writing the OS image to e.MMC, it is never acting as a USB host, right?

Do I need to change some setting in software to disable OTG functionality? Or is disconnecting OTG_OC, OTG_PWR, and ID sufficient to make sure the processor always acts as a USB peripheral?

Thanks

Re: i.mx 8M Mini: Required USB pins to provision processor?

Yuri — Mon, 15 Mar 2021 05:12:03 GMT

@adevries
Hello,

Correct - when the processor is in serial download mode and writing the OS image
to e.MMC, it is never acting as a USB host.

When the USB ID is left floating means USB device mode. This is true as much as software
follows USB specs.

Regards,
Yuri.

Re: i.mx 8M Mini: Required USB pins to provision processor?

adevries — Mon, 15 Mar 2021 16:32:46 GMT

great, thank you for the information!