how much moving power do you need?  Big or small steppers.
The smallest,  lowest cost I have found are at SPARK FUN.COM  A stepper 
motor and stepper driver sell for about $15  each  at that site. use 
parallel port for control of up to  4 AXES.

Check out PROBOTIX or HOBBYCNC for a start.

Check out MACH3 or EMC2 for software control.

There are a lot of parts ( stepper motors and driver boards) out there 
for the Hobby CNC market.

There are several schematics for home made things also.

Bob


PICdude wrote:
> [ I'm using the PIC tag for this for now, as there is some PIC  
> content, and we really need to see more of the PIC tag on this forum  
> lately. ]
>
> I'm searching for a multi-axis stepper-motor motion controller, but  
> the options I've found so far are pricey, so that leads to the thought  
> of rolling my own.  Don't really need another project right now, but  
> I'll make the time for it if it saves me a few hundred $$$.
>
> My requirements are relatively simple... Interface to a PC (parallel,  
> RS-232, USB, or I2C) to accept commands to move to a 3-dimensional  
> vector position (X,Y,Z) with a certain acceleration and max speed  
> value.  The controller will move to that position (coordinated),  
> accelerating and decelerating accordingly, and sending back some  
> signal to indicate that it's completed that operation.  Future  
> embellishments may include reading quadrature encoders to verify that  
> moves are successful. The controller will need to output only step/dir  
> signals for each axis, which will go to individual drivers.
>
> So my questions...
> (1) Know of any simple 3-axis controllers that will do this at a  
> relatively decent cost?  I'd need it to provide the interface protocol  
> spec, or a Linux library/API.
>
> (2) Know of any projects/circuits on the net that does this?
>
> (3) Know of any controller chips that will make this easy?  I found a  
> similar-ish controller by National semi (LM629), but it was for DC  
> servo motors.  Would be great to find a similar stepper chip.
>
> (4) As I also consider the home-brew PIC option, I'm wondering which  
> PIC would be suitable.  There would be a good bit of math, and rigid  
> timing.  I've only used PIC 16F's and 18F's to date, but I expect on  
> of the dsPIC's or 32-bit options would be ideal.
>
> Cheers,
> -Neil.
>
>
>
>
>   

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