Stepper motor controller with Attiny85

Attiny85 Stepper Controller

Today I made a fully functioning stepper controller using an Attiny85. I have written the software of Attiny in arduino code, and used an arduino leonardo as ISP.

It is absolutely open and you can see everything about this project here:

I haven't seen anyone build a stepper controller that cheap, as its cost is almost 2.50 euros. It can tolerate step signals at about 666Hz(really 1/0.0015Hz) without losing a single step and has a Step/Dir interface that need 5V Logic. It needs a 5VDC power supply.

I would like any feedback, here or as comment in the instructable as well! Any add on feature you may create (using the same circuit when possible), like sleep/enable pins, microstepping capability, and others, can be posted here, for me to keep a track of the last working "firmware" of the chip. The latest code will always be available and open source!

Sounds interesting, but you seem to have forgotten to post a link to your masterpiece.

How much current can it handle?

...R

I haven't forgotten. I just hadn't finished the instructable about it..

It can handle no current. It is just the logic unit. The current control can be achieved by connecting it to a famous ULN2003 (for small to moderate steppers) and any transistor array that can handle Amperes of current (for bigger steppers).

In other words it works with unipolar steppers only? (5/6/8 wire)

I have tested it only with unipolar. It is true. Thats because I only had unipolars at the moment.

But I can't see the reason it won't work for any other. It has to do with the driving circuit you will build for the motor. The ULN2003 will work with unipolars. But there are other possibilities too.
The Attiny circuit only drives the logic (stepping).

For example you can use 2 H-bridges for a bipolar one. That can raise the cost to almost 5euros (whole driver). It isn't that bad either.

The A1 A2 and B1 B2 get connected to the Attiny85 phase outputs...

(better add this to the instructable, it isn't that straightforward... ADDED)

Those H-bridges have shoot-through - you don't want shoot-through.

None wants it. It can be prevented via software though...
In all step combinations there isn't any High-High couple for the same Coil...
And the dynamic shoot-through can be prevented using delayMicroseconds() function in drive(...) in a different way...