I'm trying to use the A4988 stepper driver with arduino. Unfortunately after trying different ways and three boards, I could not get it to energize the motor coils even once. I verified that the motor it self works by LED test and by manually touching the coil leads to a power source in sequence. The motor is a 6 wire unipolar motor and I'm leaving out the two center taps and connecting the remaining 4 leads as mentioned on the website.
To debug why the coils are not getting energized, I have tried the minimal setup (calibration) posted by decrDude in https://forum.pololu.com/t/a4983-and-a4988-getting-started-guide/2789/1. unfortunately, that dint work either. The four motor leads just read zero volts and zero current. I have connected enable to low. Reset, Sleep to high. MS1,2,3 to low. DIR, STEP are tied to GND. VMOT reads 12 volts. My logical power supply 5v is taken from arduino and both grounds are connected.
Is there any thing else I'm missing or are there any suggestions on what to try next to debug this ? One mistake I have done initially is that I have connected the central taps to the +ve power supply. I have now reverted this and ignoring those two leads. I'm not sure if this has any way damaged the board (there were no visible signs of it).
Any help or suggestions are appreciated.