I have a ROCKPro64 v2.1 board and installed with "bionic-minimal-rockpro64-0.8.0rc6-1111-armhf.img". The system boots up is fine, but both /dev/ttyS0 and /dev/ttyS2 are not working. I don't know which pins out of a total 40 pins of Pi-2 are for UART 0 (/dev/ttyS0). Am I correct that Pin 8 is /dev/ttyS2 Tx Pin and Pin 10 is /dev/ttyS2 Rx Pin? Are these UART pins are enabled by default after system boot up? Should I do something to enable these pins in order for UART (/dev/ttyS0 or /dev/ttyS2) to work?
For a UART to work, I mean this ttyS0 or ttyS2 port is able to send out or receive characters. Currently, I am able to open and set up serial port but not able to send out or receive characters correctly. I guess those UART pins are shared with GPIO pins or multiplexed with GPIO functionality, some configurations may need to be done. Could you help me?