Projects with microcontrollers and FPGAs often have a lot of flexibility in how things get connected. My workflow for those projects is to build a sparsely connected schematic and then move to PCB to explore geometry options. Once I see what will be easy to route in PCB I start making connections based on the physical layout. Sometimes I do this by picking a starting pin and assigning them sequentially in gschem (FPGAs make this fairly easy, at least with "linear" packages). Sometimes I use 'D' and 'Shift-D' to annotate pins or bring up the whole package in PCB so I know which pins I can consider and then just route them (with auto-DRC disabled, kind of a bummer) and use the conflicts to back-annotate the PCB.
I'd really like to be able to do a couple of things more easily: 1. I'd like be able to express the design requirements in gschem and have them visible in PCB. For example, I'd like to say "connect this SRAM address bus to this bank of FPGA pins... somehow" and see that in PCB. Some kind of "meta rat" that would help me see both the geometry and the pins that are in play. 2. I'd like to be able to resolve these dependencies (even in the absence of 1, as today) by drawing lines in PCB and having the info get back to gschem automatically. Perhaps by adding a wire+netlist attribute+busripper at the appropriate pin. Does anyone know if/how good commercial tools do this? Any ideas for how to express a "meta rat"? How to visualize it? How to specify it in gschem, in a netlist, etc? Any better ideas for how a line drawn in PCB could be automatically driven back to a schematic? Perhaps as a "rat" in gschem?? -- Ben Jackson AD7GD <[EMAIL PROTECTED]> http://www.ben.com/ _______________________________________________ geda-user mailing list [email protected] http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
