How to detect motor stall using DRV8860 drive stepper

Hi Champs,

My customer is using DRV8860 to drive 2 stepper motors in home air-conditioner indoor unit. Recently they have a new requirement of detecting motor stalling, then stop the motor. They want to know how to detect stalling using DRV8860? As we know, back-EMF can be used for stall detection, would you kindly suggest how to implement this method in DRV8860 driving stepper system? 

Is there any other DRV product can realise this function and be suitable for this application?

Thanks.

Regards,

Young