Thanks, JerryChang. I have checked that lib, however, my goal is to use 6 pairs of GPIO pins and emulate that pairs as serial ports, because the external devices only communicate by UART or USB. I could use the USB ports, but I facing a problem with many devices connected to USB. In total, I intend to connect 15 devices to Jetson.
GPIO cannot be configured as a serial UART in the traditional software meaning. Sure, you can “bit bang” and work with serial data, but that data is not able to set specific data rates. Even if you could set those data rates, the GPIO timing is too unstable and would fail immediately. If you need that many “true” serial UARTs, then you are better off finding a USB serial UART. However, it is likely that the work load of that many UARTs would cause timing issues and make all UARTs fail.