How can I set the register of DRV8711

I use the DRV8711 for diving stepper motor,use the CSD88537ND for pre-drivers .The motor cann't work and the voltage in the stall is low .I considered  configuration of the registers.But how can I do?

my stepper motor features :

2.8v , 1.68A , 1.8degree , r = 1.65 ohm , l = 4.1mH