DRV8825: Using DRV8825 to drive a stepper Motor. But Motor is too hot and doesn't move

Tool/software:

The schematic is shown below:

The Reset and nSleep pins are high,but the motor doesn't move , and too hot.

Vref=1.22V    so,the chop current is set to 1.22A   

the stepper Motor is 12V rating。  Aout1=Bout1= 11.89V   ; Aout2=Bout2=0V
I can't find the voltage changing.
how to examine the design step by step ? Whether is the Chop Current too big than Motor rated? 

图如上图，接上12v步进电机后，reset 和nSleep管脚都是高电平。但是电机不运转，发热严重。

测量显示Aout1和Bout1都是11.8v左右，Aout2和Bout2接近0v. 电压不跳变。测的vref1.22v左右，

想知道按这个图chop电流=1.22/（5*0.2）=1.22A.  这个电流设置的不合理会不会导致现在的现象？比如我降低到800mA?