Hi Quadtech and James, I haven't checked all the wires are connected to the right spots, but there are a few layout issues I noticed straight off.
The 2 wires from the chip back to the current feedback resistors carry full motor current so they should be the same larger size as the 4 motor tracks. Getting the resistors closer to the chip so the current paths are smaller would be good. I know it's hard to get a single sided layout to perform really well, but nobody will really be expecting a single sided SMPS driver to perform as well as a proper plated through hole PCB so you probably just need to improve it to a reasonable level.
If you can, make the length of the tracks the same from the chip to each set of the current sense resistors. That includes the 2 tracks from the ground side of the resistors back to the main cap.
If possible the chip, sense resistors and main cap should be close together with short direct tracks. The other parts can be further away.
The 5v cap should also be closer to the chip which should be easy enough.
The other layout problem is the placing of some of the solder pads, especially the ones on the wire jumpers. If possible for a good single sided design the places where the user has to solder should be well spaced away from any other tracks, to reduce the chance of shorts and make soldering easier and more reliable. Also the size of the solder pads should be larger if possible to make for easier drilling and soldering when people make their own PCBs. Those tiny square pads on the wire jumpers are not good.
