Hi guys,
Just though I would add my 2 cents worth. I've also played with these motors a bit. The motors I've seen also have their coils in a Y configuration with a tap in the middle. I use a different driver but otherwise my approach is very similar to that of be80be.
The problem I found is that the timing is critical. When I used fixed delays the rotation is not very robust. Sometimes it would spin up, other times not. Sometimes it would spin for a while and then lose sync and stutter to a stop.
When used in a hard drive, the magnetic information on the drive platters is used to synchronize the coil timing to the rotation. Coil transitions occur at just the right moment and the motor accelerates strongly and holds speed against all perturbations.
I made a simple optical encoder disc using a laser printer and a transparency. I used an optical interrupt switch to sense the black to transparent transitions and used this to clock the coil transition. The change was dramatic. With this feedback I could easily reach the rated speed of the motor. After slowing the platter with a finger, the motor would rapidly recover its speed.
A friend of mine, Paul Rowntree, adapted this approach for use with the propeller chip and posted the project at
**broken link removed**
Hope this is helpful.
DrIguana