@Hoeken, I already have several versions of a stepper shield PCB, I'll post them in the next few days under CC so you can use them.
You might find that using the L297 makes the board very expensive, it's about $9 per chip. At that rate your board will cost about $75 in parts; If you want ohters to use your design, you might want to be aware that you can get a non-arduino commercial solution for les than that.
If you want to include driver logic, you would be much better off using an Atmega168 programmed in Arduino ( 4$) to generate the stepper pulses, rather than than three $9 chips. I don't know why that driver is so expensive, but with a single Atmega generating the control pulses, you could serially control each shield.
Daniel
Hey Daniel,
Thanks, I'd love to look at those designs. Hopefully we can come up with something that does what I want it to do, and is also useful for the rest of the community. The L297 is a bit pricey, but you can find it at decent prices. Jameco has it for $5.00: http://www.jameco.com/webapp/wcs/stores/servlet/ProductDisplay?langId=-1&storeId=10001&catalogId=10001&productId=288067
Also, I've looked up commercial 3 axis boards that use the L297/L298 combo and they generally run about $150, so this kit would still be cheaper. If I got it manufactured, it would still be competitive, and probably less than that as I'd be doing it under the not-for-profit RRRF corp. see: http://www.xylotex.com/3axBoard.htm and Technological Arts – Technological Arts LLC
As for using an atmega, one of the reasons i've read about using the L297 is because it gives you the 'chopper' style stepper driving by sensing the voltage through the coils, and adjusting it appropriately. this gives you the best possible performance for your steppers, as well as making controls super simple (step/direction). Also, I'm not much of an electronics person and the L297/L298 combo is very well documented, as well as tested. I'm intending to use this board as a base for the RepRap project, so I'd prefer to go with something tried and true. Also, I'd rather not have to write more firmware than i have to to drive the steppers... the L297 just does it all for me.
The open source part is also a big deal to me. Sure there might be commercial systems, but the stepper controller is the core of the RepRap system, and having that core be open source and modifiable is very important. I'm sure you folks at Arduino can understand
Finally, I really like the idea of an arduino shield, because once you build/buy the board, then you just insert it into the arduino board, and you're ready to go. having that full solution, ready to plug and play makes it very attractive. alot of the people involved in this project aren't especially electronically savvy, so it would be nice to have that packaged solution ready to go. for example, we have materials engineers who might be playing with different materials, or mechanical engineers playing with different positioning systems, and to be able to provide them with a solid 3 axis stepper driver would be awesome. Especially if its combined with the excellent Adruino programming environment.
This is all really exciting. I can't wait until I have the first board in my hands!!