component.dnp

What it is ¶

component.dnp(ref_des) yields one row per component marked do-not-populate in the design. The part is still in the netlist, with its class, its pins and its nets, and this relation says it is not fitted on the assembled board. Absence means the part is fitted, which is the normal case.

For hardware engineers ¶

A do-not-populate part has a footprint and copper but no part on it, usually because it is one side of an assembly option: a 0 Ohm link that selects one of two supplies, a resistor that pulls a camera line to 1.8 V beside a fitted one to 3.3 V, a TVS footprint left empty on a cost-reduced build. It does nothing electrically, so a capacitor marked DNP decouples nothing and a TVS marked DNP clamps nothing. If a review counts such a part as protection, it reads an unsafe board as safe. This relation lets a question leave those parts out.

A test point is the exception. Its pad is copper on the bare board, so a probe still lands on it, and a pad-only test point is usually marked DNP because nothing is placed on it. The shipped net.has_test_point family therefore counts unfitted test points.

For software engineers ¶

This is a unary predicate over components (see the analogy guide), keyed by ref-des so it joins component.class and component.net. To credit a part with a role, a query negates it, as in component.class(?r, "tvs"), not component.dnp(?r). The Go rules ask Model.IsFitted for the same fact, so a query and a rule credit the same parts.

Go projector ¶

componentDNPFacts in stdlib/relations/facts.go walks Model.Components() and emits a row for each unfitted ref-des, as Model.IsFitted reports it. Fittedness is read from the design (KiCad’s dnp flag) when the model is built, and the row cites the component’s own source location.

Datalog ¶

Every part the design leaves unfitted:

component.dnp(?r) => ?r

The TVS clamps that are actually fitted on a net:

component.net(?r, ?n), component.class(?r, "tvs"), not component.dnp(?r) => ?r, ?n