I wrote the attached program "keyboard.c" which sends an unbuffered keystroke to my Arduino DUE at 28800 baud.
The DUE is programmed with the attached "stepper_test.ino", which is a modification of the code provided by Sparkfun Electronics for the Big Easy stepper motor driver. My understanding is that, if I transmit over the "programming USB port" at 9600 baud, it will reprogram the DUE. However, since I am communicating at 28800 baud, communication should go as programmed.
My understanding is that if there is nothing to send, the request for input from the DUE (dueout in line 72 of the keyboard program) should result in a zero. Instead, I am getting bufr = 'k' (or some other random character).
??
PS Hopefully, someone else will find keyboard.c to be useful.