Hi - this is my first post here!

I have a NanoPi M4 v2 with a SATA hat. Am running Friendly Core (Ubuntu 18.04) off the eMMC drive. I also have four 2 TB disks connected to the SATA hat as my network storage and they are in a RAID5 configuration. Everything runs fine - the board is snappy and as expected.

I would like to connect a Matrix USB2UART module to get a serial console working and my question is relating to this. According to the wiki, the serial debug port uses UART2 (UART0 is Bluetooth, UART3 is used by ethernet and UART4 is on pins 19/21 of the 40 pin connector).

However, /dev/ttyS2 is not available.

I see /dev/ttyS0 and /dev/ttyS4 as being active/available and have searched high and low on the internet to see how to activate UART2 (and thus /dev/ttyS2) but have had no luck.

If I connect the module to pins 19 and 21 on the 40-pin connector, I am able to get the serial console working via /dev/ttyS4 ... so the board etc. are all working.

How can I enable UART2 (/dev/ttyS2)? I tried using the np-config utility but that does not seem to help. Is there some other setting that I need to adjust?