This is the firmware for the motor controllers.

Builds with msp430-gcc 3.2.3, with binutils 2.16.

Control states:
 
With the fets arrange like so:

 X T
 Y U

A B X Y T U
0 0 1 0 0 1 Forward
0 1 0 1 1 0 Backward
1 0 0 1 0 1 Brake
1 1 0 0 0 0 Off

For the two different motors:

0.A: P3.3
0.B: P3.4

1.A: P3.5
1.B: P3.6

Therefore the two bit words that need writing are:
 Forward: 0
 Backward: 1
 Brake: 2
 Off: 3