Freerouter Round Tripping Guidelines:
1. in pcbnew: establish the number of layers, and save the *.brd
file.
2. in a text editor: load the board (*.brd) file, and edit the layer
names and types. These should look something like this:
* Layer[0] Back signal
* Layer[1] Power power
* Layer[2] V2_Signal signal
* Layer[3] H1_Signal signal
* Layer[4] Ground power
* Layer[15] Front signal
Notice that after the layer name there is a layer type field, either
'signal' or 'power'. Any layer identified as 'power' will be
removed from the layer menu in Freerouter, as this will be assumed to
contain a power zone.
* in pcbnew: re-load the board, and establish board perimeter.
* in pcbnew: establish any zones, inclusive of net association.
* in pcbnew: load in the netlist so you have all the components
defined and instantiated.
* in pcbnew: do the degree of component placements you are
comfortable with. It is a little easier to accurately position
components in pcbnew than in freerouter, but either will work.
* in pcbnew: set up the netclasses. power traces might be a little
thicker. So add a netclass called 'power'. Make its traces thicker than
what you establish for netclass 'Default'. Set spacing and vias for each
netclass.
* in pcbnew: export to DSN.
* load up freerouter (keep it running for any subsequent iterations
of 6) through 14) here ).
* in freerouter: load the project's *.dsn file.
* useful, not mandatory: in freerouter: set your move snap modulus,
which seems to default to 1 internal unit. 20 mils in x and in y is
about reasonable.
* in freerouter: finish placing any components, you can change sides
of a part here also, rotate, whatever.
* in freerouter: route the board, save frequently to a *.dsn file
while routing, in case of power loss, not yet a session file but a full
*.dsn file. The full freerouter *.dsn file is a superset format, one
that fully defines the board and can be reloaded between power outages,
whereas the *.ses file is not a complete design, but with the *.brd file
constitutes a full design.
* in freerouter: when done, or when you want to back import, then
save as a session file, *.ses.
* in pcbnew: backimport the session file
* in pcbnew: at this point the zones have to be refilled. One way to
do that is to simply run DRC.
