I am working on getting my Banana-Pi BPi-M7, I wanted to see how the UBoot is booting up, I wanted to see can I change to NVMe. On the Wike/Docs page the info for the UART was a bit hard. Since this does not have the standard three pins for UART, had to figure out which of the GPIO 40 Pins work with the UART Cable.

I watched one of the video and paused, and hooked up my UART to the following pins and it working

GND = Pin 6
TXD = Pin 8 ( Remember to hook up the opposite, thus White RXD )
RXD = Pin 10 ( Remember to hook up the opposite, thus Green TXD)

Then playing with the speed, I found out the bard rate is 1500000. I hope this helps others.