Stepper voltage bemf with negative velocity

[safarir]

I am using a stepper motor in open loop mode with a KV value. When the shaft velocity is negative, the voltage.q is dropping with velocity while is should be rising which cause the torque to be limited.

I think the problem is here

// calculate the back-emf voltage if KV_rating available U_bemf = vel*(1/KV)
  if (_isset(KV_rating)) voltage_bemf = shaft_velocity/KV_rating/_RPM_TO_RADS;

It should be

// calculate the back-emf voltage if KV_rating available U_bemf = vel*(1/KV)
  if (_isset(KV_rating)) voltage_bemf = abs(shaft_velocity)/KV_rating/_RPM_TO_RADS;

[askuric]

You're absolutely right!
I'll resolve this issue right away. Thanks for the fix suggestion, however the signed value of the back emf voltage is necessary for closed loop control. The absolute value should be used for open loop control, we I'll include the abs in openloop code.
This will get into the v2.2.3 which will release very soon.