Length and matching

Length targets with .length(), match groups with .match(), how the tuner lays meanders to meet them, and where the lengths are reported. The route call and its builder methods are in routing.md; pair skew is in pairs.md.

Targets and groups

import PCB, { nets, route } from '@pcbjs/core'
import { PinHeader } from '@pcbjs/lib'

const { CLK, D0, D1 } = nets()
const J1 = PinHeader(3).connect(CLK, D0, D1)
const J2 = PinHeader(3).connect(CLK, D0, D1)

export default () => (
  <PCB name="Tuned">
    <rect layer="Edge.Cuts" x={0} y={0} w={40} h={20} />
    <J1 at="5 5" />
    <J2 at="35 5" />
    {route(J1[1]).Z(J2[1]).width(0.25).length(34)}
    {route(J1[2]).Z(J2[2]).width(0.25).match('DATA')}
    {route(J1[3]).H(20).V(14).H(35).Z(J2[3]).width(0.25).match('DATA')}
  </PCB>
)

• .length(34) is 34 mm give or take the class tolerance, else 0.1 mm; .length({ min: 40, max: 42 }) a range, either end optional; .length({ target, tolerance }) both.
• .match('DATA', tolerance?) puts the route in a group of routes, pairs or both, with the smallest tolerance of its members, each its own, the class's or 0.1 mm.
• The length is routeLength: the tracks, along their arcs, and each via's distance through the board. A pair's length is its longer track.
• Tuning runs before zones fill: targets in document order, groups by name, then pair skew. A route short of its minimum goes to its target, else the middle of its range, else its minimum and half the tolerance.
• A group aims at its longest route: a member more than the tolerance below it goes into the window from the longest less the tolerance to the longest, within its own range. A member whose maximum is below that window goes to its maximum and caps the group, as length-match says.
• The meander is a one sided serpentine of U bumps, corners arcs of half the run pitch, down to the track width where room is short, below twice the width 45 degree chamfers. It goes where the room beside a segment, clear of other parts' courtyards and silk, takes the most, and per tune grows up to maxAmplitude or shrinks to half the run pitch.
• A U bump adds at least 2 pi - 4 times the track width. Less than that grows the last meander, or one smallest bump overshoots within the range; else the route stays short and the finding says so.
• A route too long is never shortened; one without room stays short, the finding says by how much and why.
• Each tuning step is cached in the route file.
• Every track and via of a route carries route, route:<n> in document order; board.routes lists them with their targets and what tuning added, pcbjs inspect pcb.tsx --lengths prints them.