On power up a method of phase finding is required to determine the rotor position relative to the encoder count. Normally this is achieved by rotating the motor (as a stepper) until the index mark is found and then the encoder count can be zeroed. At that point utilizing the invDistPerCycle and CommutationOffset should provide proper commutation.
==Stepper Motor Control==
SnapAmp drives Stepper motors by outputting sine/cosine currents to the two Stepper Motor Coils. Each fulll sine/cosine cycle will move the motor 1/50th of a revolution (for a standard 200 full step/rev motor). KFLOP Axis Output Mode "Microstep" (chX->OutputMode=MICROSTEP_MODE). SnapAmp has high speed Digital current loops to control the motor currents by PWM'ing (33KHz) the Supply Voltage to the coils with current feedback. The current Amplitude can be configured with the MicroStepper Amplitude (chX->StepperAmplitude ). Max value of 1023 corresponds to max current of 35Amps. So for example a 2.8Amp motor would be set at:
2.8 x 1023/35 = 82