DRV8818: Dears ,My customer use drv8818 as stepper motor driver , Positive and inversion , there is a error occasionally , Set the driection then give the DRV8818 PWM ,delay 20ms , Set the opposite driection then give the DRV8818 PWM , in this case ,the

Part Number:DRV8818

Dears ,My customer use drv8818 as stepper motor driver , Positive and inversion , 
there is a error occasionally ,  Set the driection then give the DRV8818  PWM ,delay 20ms , Set the opposite driection then give the DRV8818  PWM , 
in this case ,the motor will be error :could not change the driection some times, The motor run time is 13ms , 
when delay time  prolong 50ms ,the error less ,but still happen ,the applicatin need 20ms ,please help to check the sch ,if any wrong there ? many thanks ~