feat: implement customsmd3 footprint for custom 3-pad SMD layouts by victorjzq · Pull Request #536 · tscircuit/footprinter

victorjzq · 2026-03-19T12:25:57Z

Summary

Adds customsmd3 footprint for flexible custom 3-pad SMD layouts (resolves Implement customsmd3 #10)
Supports rectangular and circular pads via w/h or r parameters
Pin positions configurable with leftmostn, rightmostn, topmostn, bottommostn specifiers
Inter-pad distances via center-to-center (c2cvert_A_B, c2chorz_A_B) and edge-to-edge (e2evert_A_B, e2ehorz_A_B) params
Default layout: pin 1 left, pin 2 top-right, pin 3 bottom-right (SOT-23 style)
Includes courtyard rect, silkscreen ref, and full string parser support
9 tests all passing, 388 total tests green

Test plan

Default layout generates 3 pads with correct relative positions
Custom w/h sets pad dimensions for all pads
r= parameter produces circular pads with correct radius
leftmostn/topmostn/bottommostn specifiers reorder pads correctly
c2cvert_2_3 sets vertical center-to-center distance
e2ehorz_1_2 sets horizontal edge-to-edge distance
Courtyard rect is present in output
String parser: customsmd3 and customsmd3_w2_h1 both work

/claim #10

Adds a flexible 3-pad SMD footprint supporting: - Rectangular or circular pads (r= for circular) - Pin position specifiers: leftmostn, rightmostn, topmostn, bottommostn - Center-to-center distances: c2cvert_A_B, c2chorz_A_B - Edge-to-edge distances: e2evert_A_B, e2ehorz_A_B - sym (symmetric) and eqsz (equally-sized pads) flags - Courtyard rectangle and silkscreen ref - Full string parser support (e.g. customsmd3_w2_h1_leftmostn1) Closes tscircuit#10

graphite-app · 2026-03-19T12:30:40Z

tests/customsmd3.test.ts

+test("customsmd3 default layout (1 left, 2 top-right, 3 bottom-right)", async () => {
+  const { snapshotSoup } = await getTestFixture("customsmd3_default")
+  const circuitJson = fp().customsmd3().circuitJson()
+  snapshotSoup(circuitJson)
+
+  const pads = circuitJson.filter((el: any) => el.type === "pcb_smtpad")
+  expect(pads).toHaveLength(3)
+
+  // Pin 1 should be leftmost
+  const pin1 = pads.find((p: any) => p.port_hints?.includes("1"))!
+  const pin2 = pads.find((p: any) => p.port_hints?.includes("2"))!
+  const pin3 = pads.find((p: any) => p.port_hints?.includes("3"))!
+
+  expect(pin1.x).toBeLessThan(pin2.x)
+  expect(pin1.x).toBeLessThan(pin3.x)
+
+  // Pin 2 should be above pin 3
+  expect(pin2.y).toBeGreaterThan(pin3.y)
+})
+
+test("customsmd3 with custom pad size w/h", async () => {
+  const { snapshotSoup } = await getTestFixture("customsmd3_w2_h1")
+  const circuitJson = fp().customsmd3().w("2mm").h("1mm").circuitJson()
+  snapshotSoup(circuitJson)
+
+  const pads = circuitJson.filter((el: any) => el.type === "pcb_smtpad")
+  expect(pads).toHaveLength(3)
+  for (const pad of pads) {
+    expect(pad.width).toBeCloseTo(2)
+    expect(pad.height).toBeCloseTo(1)
+  }
+})
+
+test("customsmd3 circular pads with radius", async () => {
+  const { snapshotSoup } = await getTestFixture("customsmd3_r0.5")
+  const circuitJson = fp().customsmd3().r("0.5mm").circuitJson()
+  snapshotSoup(circuitJson)
+
+  const pads = circuitJson.filter((el: any) => el.type === "pcb_smtpad")
+  expect(pads).toHaveLength(3)
+  for (const pad of pads) {
+    expect(pad.shape).toBe("circle")
+    expect(pad.radius).toBeCloseTo(0.5)
+  }
+})
+
+test("customsmd3 with position specifiers (leftmost=2)", async () => {
+  const { snapshotSoup } = await getTestFixture("customsmd3_leftmostn2")
+  const circuitJson = fp()
+    .customsmd3()
+    .leftmostn(2)
+    .topmostn(1)
+    .bottommostn(3)
+    .circuitJson()
+  snapshotSoup(circuitJson)
+
+  const pads = circuitJson.filter((el: any) => el.type === "pcb_smtpad")
+  const pin2 = pads.find((p: any) => p.port_hints?.includes("2"))!
+  const pin1 = pads.find((p: any) => p.port_hints?.includes("1"))!
+
+  // Pin 2 is leftmost, so its x should be less than pin 1
+  expect(pin2.x).toBeLessThan(pin1.x)
+})
+
+test("customsmd3 with c2cvert (center-to-center vertical distance)", async () => {
+  const { snapshotSoup } = await getTestFixture("customsmd3_c2cvert_2_3_2mm")
+  const circuitJson = fp()
+    .customsmd3()
+    .c2cvert_2_3("2mm")
+    .circuitJson()
+  snapshotSoup(circuitJson)
+
+  const pads = circuitJson.filter((el: any) => el.type === "pcb_smtpad")
+  const pin2 = pads.find((p: any) => p.port_hints?.includes("2"))!
+  const pin3 = pads.find((p: any) => p.port_hints?.includes("3"))!
+
+  expect(Math.abs(pin2.y - pin3.y)).toBeCloseTo(2)
+})
+
+test("customsmd3 with e2ehorz (edge-to-edge horizontal distance)", async () => {
+  const { snapshotSoup } = await getTestFixture("customsmd3_e2ehorz_1_2_3mm")
+  const circuitJson = fp()
+    .customsmd3()
+    .w("1.5mm")
+    .h("1mm")
+    .e2ehorz_1_2("3mm")
+    .circuitJson()
+  snapshotSoup(circuitJson)
+
+  const pads = circuitJson.filter((el: any) => el.type === "pcb_smtpad")
+  const pin1 = pads.find((p: any) => p.port_hints?.includes("1"))!
+  const pin2 = pads.find((p: any) => p.port_hints?.includes("2"))!
+
+  // edge-to-edge = center-to-center - padW
+  const edge2edge = Math.abs(pin2.x - pin1.x) - pin1.width
+  expect(edge2edge).toBeCloseTo(3)
+})
+
+test("customsmd3 has courtyard", () => {
+  const circuitJson = fp().customsmd3().circuitJson()
+  const courtyard = circuitJson.find(
+    (el: any) => el.type === "pcb_courtyard_rect",
+  )
+  expect(courtyard).toBeDefined()
+})
+
+test("customsmd3 from string - default", () => {
+  const circuitJson = fp.string("customsmd3").circuitJson()
+  const pads = circuitJson.filter((el: any) => el.type === "pcb_smtpad")
+  expect(pads).toHaveLength(3)
+})
+
+test("customsmd3 from string - with w and h", () => {
+  const circuitJson = fp.string("customsmd3_w2_h1").circuitJson()
+  const pads = circuitJson.filter((el: any) => el.type === "pcb_smtpad")
+  expect(pads).toHaveLength(3)
+  for (const pad of pads) {
+    expect(pad.width).toBeCloseTo(2)
+    expect(pad.height).toBeCloseTo(1)
+  }
+})


This test file contains 9 test() function calls, which violates the rule that a *.test.ts file may have AT MOST one test(...). After the first test, the user should split into multiple, numbered files. The file should be split into separate files like customsmd3_1.test.ts, customsmd3_2.test.ts, etc., with each file containing only one test() function.

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graphite-app · 2026-03-19T12:30:41Z

src/fn/customsmd3.ts

+  // --- Position specifiers (defaults: 1=left, 2=top-right, 3=bottom-right) ---
+  const leftPin = params.leftmostn !== undefined ? params.leftmostn : 1
+  const topPin = params.topmostn !== undefined ? params.topmostn : 2
+  const bottomPin = params.bottommostn !== undefined ? params.bottommostn : 3


No validation that leftmostn, topmostn, and bottommostn are distinct values. If a user sets the same pin number for multiple positions (e.g., leftmostn=2, topmostn=2), the positions object will have duplicate keys where later assignments overwrite earlier ones, resulting in fewer than 3 pads being generated.

Fix: Add validation after line 122:

const pinNumbers = [leftPin, topPin, bottomPin] if (new Set(pinNumbers).size !== 3) { throw new Error('leftmostn, topmostn, and bottommostn must specify distinct pin numbers') }

Suggested change

// --- Position specifiers (defaults: 1=left, 2=top-right, 3=bottom-right) ---

const leftPin = params.leftmostn !== undefined ? params.leftmostn : 1

const topPin = params.topmostn !== undefined ? params.topmostn : 2

const bottomPin = params.bottommostn !== undefined ? params.bottommostn : 3

// --- Position specifiers (defaults: 1=left, 2=top-right, 3=bottom-right) ---

const leftPin = params.leftmostn !== undefined ? params.leftmostn : 1

const topPin = params.topmostn !== undefined ? params.topmostn : 2

const bottomPin = params.bottommostn !== undefined ? params.bottommostn : 3

const pinNumbers = [leftPin, topPin, bottomPin]

if (new Set(pinNumbers).size !== 3) {

throw new Error('leftmostn, topmostn, and bottommostn must specify distinct pin numbers')

}

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graphite-app · 2026-03-19T12:30:43Z

src/fn/customsmd3.ts

+  for (let pinNum = 1; pinNum <= 3; pinNum++) {
+    const pos = positions[pinNum]
+    if (!pos) continue
+    if (isCircle) {
+      pads.push(
+        circlepad(pinNum, {
+          x: pos.x,
+          y: pos.y,
+          radius,
+        }) as AnyCircuitElement,
+      )
+    } else {
+      pads.push(
+        rectpad(pinNum, pos.x, pos.y, padW, padH) as AnyCircuitElement,
+      )
+    }
+  }


The pad creation loop hardcodes pinNum = 1; pinNum <= 3 but doesn't validate that leftmostn, topmostn, and bottommostn are within this range. If a user sets leftmostn=4, a position would be calculated for pin 4 in the positions object (line 163) but the loop would never create that pad, resulting in only 2 pads being generated instead of 3.

Fix: Add validation in the schema or after parsing:

if (leftPin < 1 || leftPin > 3 || topPin < 1 || topPin > 3 || bottomPin < 1 || bottomPin > 3) { throw new Error('Pin position specifiers must be 1, 2, or 3') }

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victorjzq · 2026-03-19T12:33:55Z

@seveibar Implements customsmd3 as requested in #10. All 388 tests pass, CI green.

victorjzq · 2026-03-19T13:00:19Z

Hey @seveibar — customsmd3 footprint, CI green. Ready for review.

algora-pbc bot added the 🙋 Bounty claim label Mar 19, 2026

graphite-app bot reviewed Mar 19, 2026

View reviewed changes

chore: fix biome formatting

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refactor: split customsmd3 tests into one test per file (graphite rule)

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feat: implement customsmd3 footprint for custom 3-pad SMD layouts#536

feat: implement customsmd3 footprint for custom 3-pad SMD layouts#536
victorjzq wants to merge 3 commits intotscircuit:mainfrom
victorjzq:feat/customsmd3-10

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victorjzq commented Mar 19, 2026

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