Hey guys, I’m dealing with audio circuits and I wanted to know if it’s possible to use the autorouter and assign certain connections to the top or bottom layer (for analog/digital isolation).
Also, I know the SFE CAM file turns off mirroring. If I’ve got silk on the bottom layer, and in the board view it is mirrored across the Y-Axis, should I turn on or turn off mirroring in the CAM for the bottom silk layer?
For Analog + Digital, your are better off hand routing the entire board. Alternately you could hand route the analog stuff, and auto-route the digital stuff. Just keep the digital traces away from the analog area. Create a "wall" between digital and analog using tRestrict, bRestrict, and vRestrict to prevent the auto-router from placing any digital traces in the analog area. Run the few traces that connect the analog area to the digital area through gaps in the "wall". Think of a castle, moat and drawbridge. The analog stuff is in the castle, the digital to analog traces are placed on the drawbridge, and the digital stuff is outside the moat.BretMattingly:
Hey guys, I’m dealing with audio circuits and I wanted to know if it’s possible to use the autorouter and assign certain connections to the top or bottom layer (for analog/digital isolation).Also, I know the SFE CAM file turns off mirroring. If I’ve got silk on the bottom layer, and in the board view it is mirrored across the Y-Axis, should I turn on or turn off mirroring in the CAM for the bottom silk layer?
Turn off ALL mirroring!
davep238:
For Analog + Digital, your are better off hand routing the entire board. Alternately you could hand route the analog stuff, and auto-route the digital stuff. Just keep the digital traces away from the analog area. Create a “wall” between digital and analog using tRestrict, bRestrict, and vRestrict to prevent the auto-router from placing any digital traces in the analog area. Run the few traces that connect the analog area to the digital area through gaps in the “wall”. Think of a castle, moat and drawbridge. The analog stuff is in the castle, the digital to analog traces are placed on the drawbridge, and the digital stuff is outside the moat.Turn off ALL mirroring!
Duh…of course the autorouter’s not going to reroute anything I’ve already routed. Thanks for being my common sense. Just out of curiosity, what’s vRestrict? (tRestrict and bRestrict are fairly self-explanatory)
That castle-moat-drawbridge analogy was the clearest and most helpful thing I’ve heard. Thanks for that.
As for mirroring…oops. Turned it off in the important layers, but figured I should leave it on for bottom silkscreen. Turns out I was wrong. Nothing major affected, though, just version code and the like. Copper and everything wasn’t mirrored, so that’s good.
vRestrict prevents the autorouter from dropping a via in that area.