Initial Ti375 GNSS IMU board design and documentation

2026-08-15 18:09:17 +03:00
commit b706197667
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+#!/usr/bin/env python3
+"""Install deterministic 0.8-mm-pitch dogbone escapes for connected Ti375 balls."""
+
+from __future__ import annotations
+
+import argparse
+import shutil
+from pathlib import Path
+
+import pcbnew
+
+
+ROOT = Path(__file__).resolve().parents[1]
+DEFAULT_INPUT = ROOT / "hardware" / "board.kicad_pcb"
+DEFAULT_OUTPUT = ROOT / "hardware" / "board_prerouted.kicad_pcb"
+POWER_NETS = {
+    "GND", "VCC0V95", "VCC1V8", "VCC3V3", "VCC3V0_DIG",
+}
+
+
+def mm(value: float) -> int:
+    return pcbnew.FromMM(value)
+
+
+def add_segment(board: pcbnew.BOARD, pad: pcbnew.PAD,
+                end: pcbnew.VECTOR2I, width_mm: float) -> None:
+    track = pcbnew.PCB_TRACK(board)
+    track.SetStart(pad.GetPosition())
+    track.SetEnd(end)
+    track.SetWidth(mm(width_mm))
+    track.SetLayer(pcbnew.F_Cu)
+    track.SetNet(pad.GetNet())
+    track.SetLocked(True)
+    board.Add(track)
+
+
+def add_via(board: pcbnew.BOARD, pad: pcbnew.PAD,
+            position: pcbnew.VECTOR2I) -> None:
+    via = pcbnew.PCB_VIA(board)
+    via.SetPosition(position)
+    via.SetWidth(mm(0.45))
+    via.SetDrill(mm(0.225))
+    via.SetLayerPair(pcbnew.F_Cu, pcbnew.B_Cu)
+    via.SetNet(pad.GetNet())
+    via.SetLocked(True)
+    board.Add(via)
+
+
+def main() -> None:
+    parser = argparse.ArgumentParser()
+    parser.add_argument("input", nargs="?", type=Path, default=DEFAULT_INPUT)
+    parser.add_argument("output", nargs="?", type=Path, default=DEFAULT_OUTPUT)
+    args = parser.parse_args()
+
+    board = pcbnew.LoadBoard(str(args.input))
+    fpga = board.FindFootprintByReference("U1")
+    if fpga is None:
+        raise RuntimeError("U1 Ti375 footprint is missing")
+    centre = fpga.GetPosition()
+    occupied: set[tuple[int, int]] = set()
+    counts = {"power": 0, "signal": 0}
+
+    for pad in fpga.Pads():
+        if not pad.GetNetname():
+            continue
+        position = pad.GetPosition()
+        # Move each ball toward its package quadrant.  Centre-row/column balls
+        # use the positive direction, leaving a full 0.8-mm via grid without
+        # duplicated interstitial locations.
+        dx = 0.4 if position.x >= centre.x else -0.4
+        dy = 0.4 if position.y >= centre.y else -0.4
+        via_position = pcbnew.VECTOR2I(position.x + mm(dx), position.y + mm(dy))
+        key = (via_position.x, via_position.y)
+        if key in occupied:
+            raise RuntimeError(f"Duplicate dogbone via at {key} for U1.{pad.GetNumber()}")
+        occupied.add(key)
+        is_power = pad.GetNetname() in POWER_NETS
+        add_segment(board, pad, via_position, 0.15 if is_power else 0.10)
+        add_via(board, pad, via_position)
+        counts["power" if is_power else "signal"] += 1
+
+    if not pcbnew.ZONE_FILLER(board).Fill(board.Zones()):
+        raise RuntimeError("Zone fill failed after BGA fanout")
+    pcbnew.SaveBoard(str(args.output), board)
+    for suffix in (".kicad_pro", ".kicad_dru"):
+        source = args.input.with_suffix(suffix)
+        if source.exists():
+            shutil.copyfile(source, args.output.with_suffix(suffix))
+    print(f"Installed {counts['power']} power/GND and {counts['signal']} signal dogbones")
+    print(f"Saved {args.output}")
+
+
+if __name__ == "__main__":
+    main()