power-input-not-driven

Remedy ¶

Connect the supply pin to the rail that feeds it, and check that the rail itself reaches its regulator. An undriven VDD is usually a missed wire rather than a missing supply.

What it means ¶

A net that has a power-input pin (a VCC/VDD/rail-consuming pin) but no power source: no power-output pin and no power flag asserting the rail is fed elsewhere.

Why engineers want it ¶

This is KiCad’s ERCE_POWERPIN_NOT_DRIVEN, and the reason power flags exist. A rail is often drawn as a named net (+3V3) with the regulator on another sheet; capture tools cannot see the source without either a power-output pin on the net or an explicit flag. A power-input with neither is almost always a real omission, where the rail was named but never connected.

Impact ¶

The part (or a whole supply domain) is unpowered. It is one of the highest-consequence capture errors and only shows up at first power-on.

Scope note ¶

Needs the power-in / power-out split (a reader that collapses both to a generic power pin cannot distinguish source from sink, so the rule does not fire). A power flag on the net, recorded by the reader, counts as driven.

Concretely, the rule is gated OFF on a source format that does not type power OUTPUTS. EDIF’s port grammar carries only INPUT/OUTPUT/INOUT and IPC-2581 is a board format with no pin electrical types (the design.types_power_out fact). There a rail’s driver reads as a plain input, so “no power source” would false-fire on every switched or derived rail. WS3-072 PR2 stamps the power-INPUT side so the power-in-only rules (decoupling-present, input-protection) work on EDIF; this rule waits for the symmetric power-OUTPUT stamp (PR3) before it can run there soundly.

Query structure ¶

select nets with a power-input, no driver, and no power flag.

select N in nets where any(power_in(P)) and not any(driver(P)) and not power_driven(N)

Reads: net.attributes (power_driven, external), on_net, pin.electrical_type. Tier R.