Hi Alan
I didn't mean to imply that this was the same as the lmd18245 boards. Those are very good systems and are ideal for someone looking for a proven design. I only made the comparison because I actually have a set of lmd's on hand and was previously trying to decide which was easiest to throw together.
I think this approach is very appealing for those on a very limited budget and for those who like to do things just to learn. All the parts are easy to get and nothing is particularly expensive. Programming the MCU is a non issue since the programmer just 3 zeners and 3 resistors connected to a com port.
It would be great if you are interested in looking at the circuit also. It is very preliminary and can definately be refined.
Possible improvements might be:
-use a attiny2313 or mega8 instead. The at90s2313 is only good for 10Mhz and is being taxed to the limits. (although code has not been optimized yet)
-connect the unused op amp to a diodes to sense temperature, for thermal protection.
-opto coupling the step/dir signals.
-micro stepping.  |