i.MX8MP USB 2.0/3.0 usage

[kccarpenter]

Hi all, I'm working through a design and wanted to get some clarification on the USB ports on the iMX8M PLUS mcu. I see that it has 4 separate PHYs, two USB2 and 2 USB3. Can those ports be used completely separately? As in, can I connect two USB 2 devices and 2 USB 3 devices (for a total of four different devices) at once? Additionally, do the paired USB 2.0/3.0 PHYs share bandwidth in any internal upstream interface? If I saturate USB 3.0 port 1, could I end up starving USB 2.0 port 1 of bandwidth?

Thank you

[brian14]

Hi @kccarpenter,

Please accept my apologies for the delayed reply.

Based on the iMX8MPlus Reference Manual this processor has 2 USB 3.0 Phys
However, these 2 ports support both USB 2.0, and USB 3.0 speeds. Here are the specifications for this module and specifications for USB 2.0 and USB 3.0:

"The USB 3.0 PHY supports the USB 3.0 SuperSpeed (5 Gbps) protocol and data rate and is backward compatible with USB 2.0 high-speed (480 Mbps), full-speed (12 Mbps), and low-speed (1.5 Mbps) protocols and data rates."

Related to your question about using 4 ports. As I mentioned this processor has only 2 PHYs but can support four programmable, bidirectional USB endpoints. Means that these 4 endpoints' communications share bandwidth and electric characteristics.
You can program using the Universal Serial Bus Controller section in the iMX8MPlus Reference Manual.

Best regards, Brian.