Stepper Motor Driver 2.1
Stepper Motor Driver v2.1
This board design aimed to solve the problems of the Stepper Motor Driver v2.0, as well as offer some unique improvements of its own. The fundamental change was a switch from the A3977 to the Allegro A3979 which is pin-compatible, but offered much higher step resolution, up to 1/16th stepping. Unfortunately the chip was only offered in the TSSOP package, which is a super tiny SMT part. After weeks of fighting with the routing of traces, and issues of trace width, copper thickness, etc., the A3979 chip was abandoned.
You can access the design files on Sourceforge.
The board was never actually produced, as work was started in favor of the Stepper Motor Driver v2.2 design.