This is Revision 1.3 of the 7x Stepper Driver.
- Added resistors on SPI1.
- Changed to new SWD format.
- Added protection against wrong PSU polarity.
- Moved leds into board.
- Major improvement on ground planes.
- Previous change on 1.2 was that I turned the Connectors around.
I re-routed the entire module from scratch and created ground planes on both sides. The new technique is to use the top-side as much as possible to leave the bottom side as much as possible. But, I also added the ground plane top side and added extra connections to ensure that all fragments are connected to ground on bottom side.
The reason I abandoned ground plane on top-side was because of the number of short-cuts I experienced. I have since then invested in microscope that makes it possible to actually see if I have a shortcut. This is regardless only a problem on the prototypes where I do manual assembly.
Here you see the top plane (blue) that get very fragmented since it carry a majority of the lanes. The good thing is that I can ground icelands with a single place through.
This is the bottom layer (red) that now is more or less one solid ground plane with minimal fragmentation. This is a major improvement from the previous Version.