pin.net

What it is ¶

pin.net(ref_des, pin, net) yields the net a pin lands on, where net is the resolved net name. A row is emitted only for a connected pin; a pin wired to nothing produces no row. The absence of a row is the queryable signal for “this pin is unconnected.”

For hardware engineers ¶

This is the connectivity answer at pin granularity: which node each pin is tied to after net solving. A pin with no row is one the read found nothing joined to. You query it to trace a part’s connections, or, by its absence, to find dangling or unconnected pins. Because it is keyed by (ref_des, pin), it is the join point between a pin and everything the net-tier relations know about the node it sits on (its fan-out, whether it is a rail, whether it is bus-like).

For software engineers ¶

A net is a shared channel aliasing fields of many instances (ANALOGY.md). pin.net is the binding of one field to the channel it aliases: the member-to-net edge. Rows are 1:1 with connected pins. The “absent if unconnected” semantics matter: an unconnected pin is not a row with an empty net, it is no row at all, so a query that wants unconnected pins asks for a pin with no matching pin.net rather than testing a net string for emptiness. Because a pin belongs to exactly one net by definition, a well-formed read gives at most one pin.net row per pin (two would be the pin_net_conflict integrity break).

Go projector ¶

pinFacts in check/facts.go calls Model.PinNetName(ref, des) for each pin and emits a pin.net(ref_des, pin, net) row only when the returned name is non-empty. PinNetName looks the pin up in the model’s pin-to-net index (built once at load from the solved nets’ connections) and returns "" for a pin that no net claims. So a connected pin yields exactly one row, an unconnected pin yields none, and the design’s whole set of pin.net rows is empty when there is no part-pin data.

Datalog ¶

Every connected pin and its net:

pin.net(?r, ?p, ?n) => ?n

Join to rail to find the pins that connect directly to a power or ground rail:

pin.net(?r, ?p, ?n), rail(?n) => ?r