Hello,
Could you clarify whether the DRV8711 can cause the asymmetry? I already wrote about several reasons why the asymmetry cannot be explained by the motor completely. We observe that already after powering on and enabling the DRV8711 (w/o stepping), the signals at the motor coils are not symmetrical and their patterns change with the DIR signal or RDIR bit.
The question is, if this observed asymmetry can be explained by the internal architecture of the DRV8711. We do not believe that it can come from imperfect layout or the components around the DRV8711, since the TI board DRV8711EVM and our own design show the same behavior.
We would be grateful for any hint that would help us to identify the real reason for our observations. If the asymmetry is really caused by the DRV8711, as we are worrying about, the only solution for our application would be another motor controller.