Add configurable SMT pad pair footprint

src/fn/index.ts

@@ -86,6 +86,7 @@ export { fpc } from "./fpc"
 export { smbf } from "./smbf"
 export { sot323 } from "./sot323"
 export { smtpad } from "./smtpad"
+export { smtpadpair } from "./smtpadpair"
 export { smdpushbutton } from "./smdpushbutton"
 export { smdslideswitch } from "./smdslideswitch"
 export { smdpinheader } from "./smdpinheader"

src/fn/smtpadpair.ts

@@ -0,0 +1,120 @@
+import {
+  type AnyCircuitElement,
+  type PcbCourtyardRect,
+  type PcbSilkscreenPath,
+  length,
+} from "circuit-json"
+import { z } from "zod"
+import { rectpad } from "../helpers/rectpad"
+import { type SilkscreenRef, silkscreenRef } from "../helpers/silkscreenRef"
+import { base_def } from "../helpers/zod/base_def"
+
+const positiveLength = length.refine((value) => value > 0, {
+  message: "pad dimensions must be positive",
+})
+
+export const smtpadpair_def = base_def
+  .extend({
+    fn: z.literal("smtpadpair"),
+    num_pins: z.literal(2).default(2),
+    px: length.default("2mm").describe("pin 2 x offset from pin 1"),
+    py: length.default("0mm").describe("pin 2 y offset from pin 1"),
+    pw: positiveLength.default("1mm").describe("shared pad width"),
+    ph: positiveLength.default("1mm").describe("shared pad height"),
+    p1w: positiveLength.optional().describe("pin 1 pad width override"),
+    p1h: positiveLength.optional().describe("pin 1 pad height override"),
+    p2w: positiveLength.optional().describe("pin 2 pad width override"),
+    p2h: positiveLength.optional().describe("pin 2 pad height override"),
+  })
+  .superRefine(({ px, py }, ctx) => {
+    if (px === 0 && py === 0) {
+      ctx.addIssue({
+        code: z.ZodIssueCode.custom,
+        message: "smtpadpair pads must have a non-zero center offset",
+        path: ["px", "py"],
+      })
+    }
+  })
+  .transform((parameters) => ({
+    ...parameters,
+    p1h: parameters.p1h ?? parameters.ph,
+    p1w: parameters.p1w ?? parameters.pw,
+    p2h: parameters.p2h ?? parameters.ph,
+    p2w: parameters.p2w ?? parameters.pw,
+  }))
+
+export const smtpadpair = (
+  rawParams: z.input<typeof smtpadpair_def>,
+): { circuitJson: AnyCircuitElement[]; parameters: any } => {
+  const parameters = smtpadpair_def.parse(rawParams)
+  const { px, py, p1w, p1h, p2w, p2h } = parameters
+  const pin1 = { x: -px / 2, y: py === 0 ? 0 : -py / 2 }
+  const pin2 = { x: px / 2, y: py / 2 }
+  const pads = [
+    rectpad(1, pin1.x, pin1.y, p1w, p1h),
+    rectpad(2, pin2.x, pin2.y, p2w, p2h),
+  ]
+
+  const centerDistance = Math.hypot(px, py)
+  const outward = {
+    x: -px / centerDistance,
+    y: -py / centerDistance,
+  }
+  const perpendicular = { x: -outward.y, y: outward.x }
+  const pin1Radius =
+    Math.abs(outward.x) * (p1w / 2) + Math.abs(outward.y) * (p1h / 2)
+  const arrowTip = {
+    x: pin1.x + outward.x * (pin1Radius + 0.12),
+    y: pin1.y + outward.y * (pin1Radius + 0.12),
+  }
+  const arrowBaseCenter = {
+    x: arrowTip.x + outward.x * 0.3,
+    y: arrowTip.y + outward.y * 0.3,
+  }
+  const pin1Marker: PcbSilkscreenPath = {
+    type: "pcb_silkscreen_path",
+    layer: "top",
+    pcb_component_id: "",
+    pcb_silkscreen_path_id: "pin1_marker",
+    route: [
+      {
+        x: arrowBaseCenter.x + perpendicular.x * 0.16,
+        y: arrowBaseCenter.y + perpendicular.y * 0.16,
+      },
+      arrowTip,
+      {
+        x: arrowBaseCenter.x - perpendicular.x * 0.16,
+        y: arrowBaseCenter.y - perpendicular.y * 0.16,
+      },
+    ],
+    stroke_width: 0.1,
+  }
+
+  const copperMinX = Math.min(pin1.x - p1w / 2, pin2.x - p2w / 2)
+  const copperMaxX = Math.max(pin1.x + p1w / 2, pin2.x + p2w / 2)
+  const copperMinY = Math.min(pin1.y - p1h / 2, pin2.y - p2h / 2)
+  const copperMaxY = Math.max(pin1.y + p1h / 2, pin2.y + p2h / 2)
+  const courtyard: PcbCourtyardRect = {
+    type: "pcb_courtyard_rect",
+    pcb_courtyard_rect_id: "",
+    pcb_component_id: "",
+    center: {
+      x: (copperMinX + copperMaxX) / 2,
+      y: (copperMinY + copperMaxY) / 2,
+    },
+    width: copperMaxX - copperMinX + 0.5,
+    height: copperMaxY - copperMinY + 0.5,
+    layer: "top",
+  }
+  const refY = outward.y > 0 ? copperMinY - 0.8 : copperMaxY + 0.8
+  const ref: SilkscreenRef = silkscreenRef(
+    (copperMinX + copperMaxX) / 2,
+    refY,
+    0.5,
+  )
+
+  return {
+    circuitJson: [...pads, pin1Marker, ref, courtyard],
+    parameters,
+  }
+}

src/footprinter.ts

@@ -475,6 +475,9 @@ export type Footprinter = {
     soup: () => AnySoupElement[]
     circuitJson: () => AnyCircuitElement[]
   }
+  smtpadpair: () => FootprinterParamsBuilder<
+    "px" | "py" | "pw" | "ph" | "p1w" | "p1h" | "p2w" | "p2h"
+  >
   platedhole: () => FootprinterParamsBuilder<
     "d" | "hd" | "r" | "hr" | "pd" | "pr"
   >
@@ -565,6 +568,15 @@ export const string = (def: string): Footprinter => {
           v: pin1LocationMatch[2],
         }
       }
+      const numberedPadParameterMatch = s.match(
+        /^(p[12][whxy])([\(\d\.\+\-\?].*)$/i,
+      )
+      if (numberedPadParameterMatch) {
+        return {
+          fn: numberedPadParameterMatch[1]!.toLowerCase(),
+          v: numberedPadParameterMatch[2],
+        }
+      }
       const m = s.match(/([a-zA-Z]+)([\(\d\.\+\-\?].*)?/)
       if (!m) return null
       const [, rawFn, v] = m

tests/smtpadpair.test.ts

@@ -0,0 +1,50 @@
+import { expect, test } from "bun:test"
+import { convertCircuitJsonToPcbSvg } from "circuit-to-svg"
+import { fp } from "../src/footprinter"
+
+const getPadGeometry = (footprint: string) =>
+  fp
+    .string(footprint)
+    .circuitJson()
+    .filter((element) => element.type === "pcb_smtpad")
+    .map(({ x, y, width, height, port_hints }) => ({
+      x,
+      y,
+      width,
+      height,
+      port_hints,
+    }))
+
+test("smtpadpair supports independently sized pads", () => {
+  const footprint = "smtpadpair_px2.1mm_ph1mm_p1w2mm_p2w1.2mm"
+  const circuitJson = fp.string(footprint).circuitJson()
+
+  expect(getPadGeometry(footprint)).toEqual([
+    { x: -1.05, y: 0, width: 2, height: 1, port_hints: ["1"] },
+    { x: 1.05, y: 0, width: 1.2, height: 1, port_hints: ["2"] },
+  ])
+  expect(convertCircuitJsonToPcbSvg(circuitJson)).toMatchSvgSnapshot(
+    import.meta.path,
+    "asymmetric",
+  )
+})
+
+test("smtpadpair supports a signed vertical pad offset", () => {
+  const footprint = "smtpadpair_px13.45mm_py-2.54mm_pw2.5mm_ph2.55mm"
+  const circuitJson = fp.string(footprint).circuitJson()
+
+  expect(getPadGeometry(footprint)).toEqual([
+    { x: -6.725, y: 1.27, width: 2.5, height: 2.55, port_hints: ["1"] },
+    { x: 6.725, y: -1.27, width: 2.5, height: 2.55, port_hints: ["2"] },
+  ])
+  expect(convertCircuitJsonToPcbSvg(circuitJson)).toMatchSvgSnapshot(
+    import.meta.path,
+    "staggered",
+  )
+})
+
+test("smtpadpair rejects coincident pads", () => {
+  expect(() => fp.string("smtpadpair_px0mm_py0mm").circuitJson()).toThrow(
+    "non-zero center offset",
+  )
+})