Why do everyone latch onto bit-banging pins from Linux??? Isn't that going to exhibit wildly unpredictable delays? Wouldn't you normally compartmentalize hardware handling into an OS-free or hard-realtime microcontroller and let the uC communicate with host CPU in less-realtime manners?

You can roll your own "RGB temperature sensing modem" and get/set values with `bash` and `expect` over ttyUSB, no one PWM controls RGB LEDs on a gaming keyboard straight from a task tray app. Trying to wrestle GPIO problems that way is going to be unnecessarily hard.