hi, I have a brand new R3 v 1.1 I purchased from Amazon. it came with a CH431 UART and with a jumper between the VCC and 3v3 pins for whatever reason, does not work with it on or off. I followed these instructions to write the img to a microSD card found here: https://wiki.banana-pi.org/Getting_Started_with_BPI-R3#Wifi_.26_Serial_cable There was a udev problem where the CH431 was not being properly detected, but I fixed that and it is now. However, I can’t get any output on the terminal. it seems the settings are 115200/8/n/1, set it to that and it doesn’t work. the image I’m using is the latest one from OpenWRT. what am I doing wrong?
Try to swap Tx and Rx cable.
Tx cable should be connected to Rx on BPI-R3. Rx cable should be connected to Tx.
Also you need drivers for your CH431.
That (swapping TX and RX) is exactly what it was. 
Thank you.