Implement UTDFN-4-EP(1x1) / utdfn exposed-pad footprint

src/fn/index.ts

@@ -22,6 +22,7 @@ export { sot886 } from "./sot886"
 export { sot23 } from "./sot23"
 export { sot25 } from "./sot25"
 export { dfn } from "./dfn"
+export { utdfn } from "./utdfn"
 export { do219ad } from "./do219ad"
 export { pinrow } from "./pinrow"
 export { headermodule } from "./headermodule"

src/fn/utdfn.ts

@@ -0,0 +1,33 @@
+import type { AnyCircuitElement } from "circuit-json"
+import { dfn } from "./dfn"
+import type { DfnInput } from "./dfn"
+
+const defined = (v: Record<string, unknown>) =>
+  Object.fromEntries(
+    Object.entries(v).filter(([, value]) => value !== undefined),
+  )
+
+/**
+ * UDFN / UTDFN with an exposed thermal pad.
+ *
+ * Defaults follow KiCad UDFN-4-1EP_1x1mm_P0.65mm_EP0.48x0.48mm:
+ * four 0.22mm x 0.25mm pads at +-0.54mm on 0.65mm pitch and a
+ * 0.48mm x 0.48mm center exposed pad. `utdfn4ep`, `utdfn-4-ep`, and
+ * `UTDFN-4-EP(1x1)` all resolve to this generator with four pins.
+ */
+export const utdfn = (
+  raw_params: DfnInput,
+): { circuitJson: AnyCircuitElement[]; parameters: any } => {
+  return dfn({
+    ...defined({
+      num_pins: 4,
+      w: "1.3mm",
+      p: "0.65mm",
+      pl: "0.22mm",
+      pw: "0.25mm",
+      thermalpad: "0.48mmx0.48mm",
+    }),
+    ...defined(raw_params as Record<string, unknown>),
+    fn: "utdfn",
+  } as DfnInput)
+}

src/footprinter.ts

@@ -50,6 +50,34 @@ type CommonPassiveOptionKey =
   | "nonpolarized"
   | "textbottom"
 
+type DfnOptionKey =
+  | "w"
+  | "p"
+  | "pw"
+  | "pl"
+  | "missing"
+  | "pillpads"
+  | "thermalpad"
+  | "thermalpadcenteroffsetx"
+  | "thermalpadcenteroffsety"
+  | "thermalvias"
+  | "thermalviapitch"
+  | "thermalviaid"
+  | "thermalviaod"
+  | "cornerpads"
+  | "cornerpadcutlength"
+  | "bodywidth"
+  | "bodylength"
+  | "bodythickness"
+  | "standoff"
+  | "terminalinset"
+  | "terminallength"
+  | "terminalwidth"
+  | "terminalpitch"
+  | "terminalthickness"
+  | "pin1terminalchamfer"
+  | "pin1markwidth"
+
 export type Footprinter = {
   dip: (
     num_pins?: number,
@@ -196,36 +224,8 @@ export type Footprinter = {
     | "thermalpadcenteroffsetx"
     | "thermalpadcenteroffsety"
   >
-  dfn: (
-    num_pins?: number,
-  ) => FootprinterParamsBuilder<
-    | "w"
-    | "p"
-    | "pw"
-    | "pl"
-    | "missing"
-    | "pillpads"
-    | "thermalpad"
-    | "thermalpadcenteroffsetx"
-    | "thermalpadcenteroffsety"
-    | "thermalvias"
-    | "thermalviapitch"
-    | "thermalviaid"
-    | "thermalviaod"
-    | "cornerpads"
-    | "cornerpadcutlength"
-    | "bodywidth"
-    | "bodylength"
-    | "bodythickness"
-    | "standoff"
-    | "terminalinset"
-    | "terminallength"
-    | "terminalwidth"
-    | "terminalpitch"
-    | "terminalthickness"
-    | "pin1terminalchamfer"
-    | "pin1markwidth"
-  >
+  dfn: (num_pins?: number) => FootprinterParamsBuilder<DfnOptionKey>
+  utdfn: (num_pins?: number) => FootprinterParamsBuilder<DfnOptionKey>
   do219ad: () => FootprinterParamsBuilder<
     | "p"
     | "pw"
@@ -650,6 +650,7 @@ const normalizeDefinition = (def: string): string => {
     .replace(/^sot-223-(\d+)(?=_|$)/i, "sot223_$1")
     .replace(/^to-220f-(\d+)(?=_|$)/i, "to220f_$1")
     .replace(/^jst_(ph|sh|zh|xh)_(\d+)(?=_|$)/i, "jst$2_$1")
+    .replace(/^u?t?dfn-(\d+)-ep(?:\([^)]*\))?(?=_|$)/i, "utdfn$1ep")
 }
 
 const normalizeMicrometerLengths = (value: string): string =>

tests/utdfn.test.ts

@@ -0,0 +1,58 @@
+import { test, expect } from "bun:test"
+import { convertCircuitJsonToPcbSvg } from "circuit-to-svg"
+import type { PcbSmtPad } from "circuit-json"
+import { fp } from "../src/footprinter"
+
+const isSignalPad = (p: PcbSmtPad) =>
+  p.port_hints?.some((h) => /^\d+$/.test(h)) ?? false
+
+test("utdfn4ep matches the KiCad UDFN-4-1EP_1x1mm_P0.65mm_EP0.48x0.48mm pad geometry", () => {
+  const soup = fp.string("utdfn4ep").circuitJson()
+  const pads = soup.filter(
+    (e): e is PcbSmtPad => e.type === "pcb_smtpad" && e.shape === "rect",
+  )
+
+  const signalPads = pads
+    .filter(isSignalPad)
+    .sort((a, b) => Number(a.port_hints?.[0]) - Number(b.port_hints?.[0]))
+
+  expect(signalPads).toHaveLength(4)
+  for (const pad of signalPads) {
+    if (pad.shape !== "rect") throw new Error("expected rect pad")
+    expect(pad.width).toBeCloseTo(0.22)
+    expect(pad.height).toBeCloseTo(0.25)
+  }
+  const padXY = (p: PcbSmtPad) => {
+    if (!("x" in p) || !("y" in p)) throw new Error("pad has no x/y")
+    return [p.x, p.y]
+  }
+  expect(signalPads.map(padXY)).toEqual([
+    [-0.54, 0.325],
+    [-0.54, -0.325],
+    [0.54, -0.325],
+    [0.54, 0.325],
+  ])
+
+  const thermalPad = pads.find((p) => p.port_hints?.includes("thermalpad"))
+  if (!thermalPad || thermalPad.shape !== "rect") {
+    throw new Error("expected a rect thermal pad")
+  }
+  expect(thermalPad.x).toBeCloseTo(0)
+  expect(thermalPad.y).toBeCloseTo(0)
+  expect(thermalPad.width).toBeCloseTo(0.48)
+  expect(thermalPad.height).toBeCloseTo(0.48)
+
+  const svgContent = convertCircuitJsonToPcbSvg(soup)
+  expect(svgContent).toMatchSvgSnapshot(import.meta.path, "utdfn4ep")
+})
+
+test("utdfn accepts an explicit pin count", () => {
+  const soup = fp.string("utdfn6").circuitJson()
+  const signalPads = soup.filter(
+    (e): e is PcbSmtPad => e.type === "pcb_smtpad" && isSignalPad(e),
+  )
+  expect(signalPads).toHaveLength(6)
+
+  const svgContent = convertCircuitJsonToPcbSvg(soup)
+  expect(svgContent).toMatchSvgSnapshot(import.meta.path, "utdfn6")
+})