I have s109 driver and I follow the schematic diagram wiring, but my stepper motor ( minebea stepper 23LM-C001-17 , 1.14A, 5.7v, unipolar , Nema23) is not moving anything!!
I adjust Vref to 0.57v according its formula (current limit=Vref*2)
my power supply is 12v , 2A.
MS3 must be connected to HIGH for Full step mode ( microstepping table) .
I attach my wiring according to its web site. (MS3 to High is connected but Enable pin is not connected in my wiring )
this stepper motor work with A4988 driver properly.