updated a little bit. (so informative, right?  :P)
Read the changes to Keyboard_Controller.c if you really want to see what I changed :P
Calibration works now!
I've just finished calibrating my own hardware.
The 12th bit of the 16-bit shift register needs to be connected to a toggle switch that toggles high/low. Every time you toggle, the calibration has a finer and finer sweep. This allows one to calibrate all twelve of the output trim pots of the of the DAC one at a time in descending order as you keep making the resolution of the sweep finer and finer (and a lower and lower amplitude sweep).
when the calibration sweep becomes too fine, the calibration resets to it's original full sweep.
fixed the initial calibration resolution.
The calibration mode would start on the second fine-ness. Now the code is set up to where it starts at the most coarse and works its way down to the finest sweep.