I have a raspberry pi compute module 3 on an I/O board in which gpio 12 is contolling the mode in ltc 2873. If it is ground it will be working in the RS 232 mode. so if I have to write something into it which port should I be using for the serial communication . should I be using tty1 that is the port for Uart R_X and UART t_x itself. I am attaching the schematic along with this and I have to take the output from the JP3 section as in the schematic. Can someone pls help me figure it out.