ERROR: No footprint for ATMEGA16U2-MU/U4.

[devbisme]

ERROR: No footprint for ATMEGA16U2-MU/U4.

[xesscorp]

I generated the .net file for the Arduino project and the devices shown above have no "footprint" fields. So when netlist_to_skidl generated the SKiDL file, these parts had no footprints and caused the errors.

All the other parts in the .net file had footprint fields populated with "~", so they didn't have real footprints, either. But all SKiDL cares about is that there is something in the footprint field, even if it's not a valid footprint. The invalid footprint will be detected when the netlist is imported into PCBNEW.

You'll have to instantiate real footprints into the SKiDL code. There used to be a separate program called CVPCB that could be used to assign footprints to parts in a netlist file. But that program was integrated into EESCHEMA when KiCad 5.0 came out. At this time, you'll have to manually assign footprints in the SKiDL code by picking them out of the KiCad .pretty folders. (Alternatively, you could use EESCHEMA to assign footprints on the original schematic, generate the netlist, and then run netlist_to_skidl on that.)

Missing components (i.e., schematic symbols) typically occur with SKiDL code that was developed using the old KiCad 4.0 part libraries but is then compiled using the new KiCad 5.0 libraries. The only thing you can do here is replace the old part names with the new names in the 5.0 libraries. (An alternative might be to use the "-cache.lib" file for a project which stores the parts for a schematic.)