I think I have the following names in my kernel:
UART3: /dev/ttyO2 --- currently used and needed for my console running on Ubuntu machinge.
UART4: /dev/ttyO3 --- not sure if I have this in my kernel.
Question: Can I use UART1 as follows: .... I wire my 3.3v gps TX and RX to the igepv2 RX1 (J960 pin 8) and TX1 (J960 pin 9). Can these pins understand 3.3v signals versus RS232 signals? In other words, will the following wiring work?
J960 pin 2 --> DB9 connector to Ubuntu
J960 pin 3 --> DB9 connector to Ubuntu
J960 pin 5 --> DB9 connector to Ubuntu
J960 pin 5 --> to GNDgps (cut existing wire to DB9 connector)
J960 pin 8 --> to RXgps (cut existing wire to DB9 connector)
J960 pin 9 --> to TXgps (cut existing wire to DB9 connector)
My other alternative is to use UART2 on J990 connector. It uses 1.8v so I would have to use a zener diode for level shifting. Also, I would have to disable bluetooth and reset the omap modes in the kernel sources file board-igep0020 for J990 pins 6 and 8 (as shown in the how-to How to set up UART2 in J990. My preference is to use UART1