I started another FreeJALduino project - "USB-CDC - XYZ CNC Router board": a 3 axis CNC Router on USB. I'm using JALv2 compiler with Jallib libraries and frejalduino.jal, a layer between Arduino language and JAL language. As for USB communications, it use USB Serial library made by Albert Faber for sending/receiving signals to/from PC. I made a testing montage and a testing program.
The final target is a functional shield for FreeJALduino board which permits direct connections of three steppers, a limit switch and three LED's as indicators. A PC host program will parse gcodes and will send strings to the board, something like here:
Is my first trial. If it will fail to work as expected, I will try USB HID approach...will see...