Currently there is 1 USB3.0 port available on the uSOM820. Increasing the number of USB3.0 port via PCIe is possible but, we have not tested this before. To enable PCIe to USB3.0, drivers for the chip might be needed. Our standard BSP release does not have the drivers to support PCIe to USB3.0. We have validated that the 2 PCIe ports are working as we support PCIe to Ethernet and PCIe to modem in our current BSP release.
If you are looking for further information please contact firstname.lastname@example.org and we can discuss how we might be able to help further.