DRV8889-Q1EVM: Stall detection

Hi Ando-san,

yuki.ando said:

Please tell me the reason why the phase difference occurs.

This is behavior of any stepper motor due to its electromagnetic construction. This is also referred to as load angle of a stepper motor. BEMF is caused by motor electromagnetic field flux whose angle changes with the load torque, sin (δ) where δ is the load angle. When the motor is unloaded the phase difference will be close to 90° and when fully loaded and on the verge of stalling it will be close to 0°. 

You can find quite a few academic papers on this subject if you search for stepper motor load angle. Thank you. 

Regards, Murugavel