Attach a schematic

The board file gives circsim the full circuit connectivity, but the matching .kicad_sch schematic adds fidelity the board can't: KiCad Sim.* model fields, symbol pin names, and the pins you marked no-connect. Attaching it is optional but recommended, especially if your board has diodes, LEDs, or parts you've annotated with simulation fields.

Why bother

Two concrete payoffs:

• Correct diode/LED polarity. A schematic symbol names its pins A (anode) and K (cathode). circsim uses that to override the footprint's pad-numbering convention, which is the difference between a diode that simulates correctly and one that's silently reversed. This is the single biggest reason to attach a schematic. See the diode-polarity trap.
• Higher-fidelity models. Any Sim.Device / Sim.Type / Sim.Model fields you (or KiCad) set on a symbol are the highest-priority model source circsim has.

How to attach

The easiest way is to do nothing. When you open a board, circsim looks in the same folder for a .kicad_sch with the same name (my-board.kicad_sch next to my-board.kicad_pcb) and attaches it if it finds one.

If the schematic lives elsewhere or has a different name, attach it by hand with a board already open:

• Drag and drop the .kicad_sch onto the circsim window.
• Click Attach schematic… (or Replace schematic…) in the Ground & Power panel and pick the file.

The Ground & Power panel's schematic row shows the attached filename in green once it's loaded, or "No schematic attached: no simulation settings from the schematic (Sim.* fields)" in red when none is attached. Hover the dotted term in the app for a definition, or see the glossary.

What you'll notice

If a diode's schematic polarity disagrees with its footprint convention, circsim corrects it and posts an informational note:

ⓘ D7: pin map corrected from schematic (A/K). Footprint convention was reversed. Override in Model Doctor if the schematic is stale.

That's the system working. It caught a would-be-reversed diode and fixed it from your design. Re-energize to see the corrected behavior.

Hierarchical schematics

This version reads only the top-level symbols of a schematic. If your design uses hierarchical sheets, parts on sub-sheets won't get Sim.* fields or pin names yet. Connectivity is unaffected: that always comes from the board.

Next

• Set ground & supply · Energize
• Pin-map precedence: the full trust order for pad↔terminal mapping.