TMCS1126: Ripple Current measurement

Hello Tom, 

Thank you for your post. 

I am most familiar with the magnetic sensing for motor encoding. 

Have you taken a look at this reference design? Abs. Angle Encoder Ref. Des. W/ Hall-Effect Sensors for Precise Motor Pos. Cont. (ti.com)

Here is also a link to a higher-level presentation on using hall-effect sensors for this: using_hall_effect_position_sensors_for_rotary_encoding_applications.pdf

I hope these help, 

Joe