RS-232 is invaluable. Give me a new piece of hardware and as long as there are 2 wires for the serial port I can port Linux kernel to it.
I have ported Linux to a custom ARM board many years ago. Started with a boot loader written in assembly and writing a single char into serial port for a debug console. It takes a single line of assembly or C. Infinitely easier than USB. From there on, I was able to unwind the whole system, develop USB drivers, TCP tunnels, etc.
I have ported Linux to a custom ARM board many years ago. Started with a boot loader written in assembly and writing a single char into serial port for a debug console. It takes a single line of assembly or C. Infinitely easier than USB. From there on, I was able to unwind the whole system, develop USB drivers, TCP tunnels, etc.