Electrical rules check
Shift+EUpdated v2.4.4At a glance
- Every pin in the library carries an electrical type, which is what makes real rules possible instead of just "is it connected"
- Catches the three that actually cost you a board: two outputs fighting, two supplies shorted, and anything wired to a no-connect pin
- Flags a power pin whose net has nothing driving it, a named net that reaches only one pin, and an undriven input-only net
- Warns when a local net name shadows a global one — the one way net scoping can bite you
- Duplicate designators are caught, and units of one multi-unit part are correctly not treated as duplicates
- Waive a finding and the waiver sticks to that finding, not to the whole rule — a new one elsewhere still reports
- Netlist problems fold into the same list, so there's one place to look
Press Shift+E or Run ERC. Findings come back in a panel, sorted by severity, each one pointing at the net and the pin it's about.
Why the pin types matter
Every pin in a JetCad3 library carries an electrical type — passive, input, output, bidirectional, tristate, power input, power output, open collector, open emitter, unspecified, or no-connect. It is captured on day one for every part, and it is what makes the interesting rules possible at all. Without a type on every pin, a rules check can only tell you whether something is connected, which you can see.
The types are compared pairwise on every net. The three conflicts that matter most:
- Two outputs on one net, fighting each other.
- Two power sources shorted together.
- Anything wired to a no-connect pin — you said you meant it to be unconnected, so a later connection to it is a contradiction worth reporting.
Open collectors are allowed to share a net with each other, because that is what they are for. A bidirectional pin on a power output gets a warning rather than an error, because it is unusual rather than wrong.
The rules
| What it catches | Severity |
|---|---|
| Two pin types that must not share a net | Error |
| A power input pin whose net has no power source | Error |
| Two parts sharing a designator | Error |
| A part with no reference designator at all | Error |
| A pin connected to nothing | Warning |
| A net of only inputs, with nothing driving it | Warning |
| A named net that reaches only one pin | Warning |
| A local net name that is global elsewhere on the board | Warning |
| Gates placed but the part's shared power unit never was | Warning |
| A global net that only appears on one sheet | Info |
A rule can be disabled or re-severitied without touching anything else, and one broken rule can never take the whole check down — it reports itself and the rest still run.
Multi-unit parts and duplicates
Four gates of one LM324 share U1 and differ only by unit, so duplication is keyed on the
designator and the unit. U1A and U1B are never flagged; two separate parts both called R1
are.
The missing_power_unit warning is the companion to that. Place gates and forget the shared power
unit and the part has no supply connection whatsoever — nothing else in the design would tell you.
No-connect flags
The No Connect tool drops an X on a pin. It silences the "pin connected to nothing" warning for that pin, and from then on anything wired to that pin is an error. The flag is a statement of intent, and the check holds you to it.
Waivers
Every finding carries a stable key, so a waiver survives re-runs and reopening the document. Waiving is per finding, never per rule — waiving one unconnected pin must not silence a genuinely new unconnected pin somewhere else next week.
Netlist diagnostics fold in
Problems found while working out connectivity — a placed part whose definition is missing from the project library, a net carrying several conflicting names, a hidden power pin that connected by name — appear in the same list. There is one place to look.