A4988 with 4 lead harddisk drive motor?

I am under the impression that hard disk drive motors with 4 leads have three terminals that share a 4th common/ground.

That being said, has anyone here used the A4988 to drive a hard disk motor? I am trying to build a driver with variable speed-otherwise a USB-IDE controller will work fine for spinning it with the stock board. I have a PIC18F4620 at my disposal with the A4988, but I am not convinced that the A4988 is the right chip for the job. Any thoughts?


The A4988 is only intended for use with two-phase stepper motors. What you are describing sounds like a three-phase brushless motor, which you cannot control with the A4988.

- Ben