After a few weeks of tinkering, I finally finished the PCB that will allow me to sense the phase currents of the stepper motor. The phase output wires of the motor driver board plug into one side and feed the motor current through 5mohm resistors. Special kelvin connections that I learned about from this article were used to improve the measurement accuracy at high-currents. INA240 current sensing amplifiers from TI were used for their enhanced PWM rejection. With these components I should be able to sense currents from -16.5-16.5A. Isolators were added to isolate the motor driver processor/power circuitry from the STM discovery board. I have also added connector ports to route the encoder and PWM signals to the STM discovery board. This board has a standard booster pack layout and will plug directly into the C2000 launchpad.