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Port and Net Selectors

Selectors are a string used to reference a port, net or any component. They're most commonly used in traces like this:

<trace from=".R1 > .pin1" to=".C1 > .pos" />

However they can also be used anywhere where a port is referenced, for example to indicate what a capacitor should decouple or a resistor should pullup to:

<resistor pullupFor=".U1 > .GPIO1" pullupTo="net.VCC" />

<capactor decouplingFor=".U1 .VCC" decouplingTo="net.GND" />

Selectors use the same semantics as CSS selectors:

  • > means "direct child"
  • . means "name" (in CSS, this can be any class name, but in tscircuit components are limited to a single name)
  • .U1 means "something with the name U1"
  • net.GND means "a net with the name GND"

Selectors don't cross subcircuit boundaries unless told to​

When a selector is specified, it's resolved relative to the subcircuit of the component where it's specified.

This means within a subcircuit the selector .U1 will match any component with the name U1 anywhere in that subcircuit without going into other subcircuits.

Subcircuits can be nested and have names, so you can use this to reference components in nested subcircuits:

<subcircuit>
  <subcircuit name="S1">
    <resistor name="R1" />
  </subcircuit>
  <capacitor name="C1" />

  {/* We must include ".S1" in the selector to select the resistor from the inner subcircuit */}
  <trace from=".S1 .R1 .pin1" to=".C1 .pos" />
</subcircuit>

Because subcircuits are isolated from each other, you can re-use reference designators in different subcircuits (globally unique reference designators are generated on export)