Wled controller v2-phi

wled-controller rev 1.0 (built, on the desk)

A 100 × 61.8 mm (golden rectangle) two-layer carrier board for an ESP32 DevKit (30-pin) running WLED with 5 V addressable LED strips (WS2812B and similar). It follows the classic WLED wiring diagram by @DedeHai: fused 5 V input, bulk capacitors on 5 V and 3.3 V, a 74AHCT125 level shifter and series data resistors.

Prices and where to buy: BOM.md. Rev 2.0: ../rev2/. Enclosure and desk base: ../enclosure/rev1/.

What is on the board

• Power input (all in parallel, before the fuse; use one at a time): DC jack 5.5/2.1 mm, 2-pin screw terminal, solder pads, 2-pin header (max 3 A).
• F1: mini blade fuse, sized to the power supply (3 A for a 5 V / 3 A PSU).
• ESP32 DevKit in two 1×15 female headers, 25.4 mm row spacing, USB-C facing the top edge, 3V3 capacitor on the left, VIN capacitor on the right.
• U1 74AHCT125: GPIO4 (D4) drives all four buffers, and each has its own series resistor:
  • MAIN: solder pads with strain relief for a JST SM pigtail (+, D, −)
  • SCREW: separate blocks on the right edge: 3× +, 3× −, and a D + − pair
  • SOLDER: D, 3× −, 3× +
  • PINS: 7-pin header + + + D − − −
• Back silkscreen: "panto" (optional pixel-art outline with --gear path.png).
• GND pours on both layers and a copper keepout under the ESP32 antenna.

Bill of materials

Regenerating

gen_board.py builds the unrouted board with KiCad's bundled Python:

"C:/Program Files/KiCad/10.0/bin/python.exe" gen_board.py --gear path/to/gear.png

It overwrites wled-controller.kicad_pcb, so do not run it after routing has started. Set KICAD10_FOOTPRINT_DIR if KiCad is installed somewhere else.

3D model

The 3D view shows the chip in its socket, a 3 A fuse and a stand-in ESP32 DevKit (KiCad's WROOM-32 model on simple boxes from ../3d/make_boxes.py). The stand-in is the ESP1 footprint: board-only, no pads, excluded from BOM and position files. gen_board.py --mask Purple changes the solder mask colour used by the 3D view.

Routing

route.py is a small grid A* router (numpy, KiCad's bundled Python). It routes every net except GND, which the pours on both layers pick up, then adds GND stitching vias:

cp wled-controller.unrouted.kicad_pcb wled-controller.kicad_pcb
"C:/Program Files/KiCad/10.0/bin/python.exe" route.py
kicad-cli pcb drc --refill-zones --save-board wled-controller.kicad_pcb

Power nets are 1.5 mm (VIN_RAW, +5V) and 1.0 mm (+3V3), signals 0.4 mm. wled-controller-gerbers.zip holds the Gerbers and drill file for the fab.

Before ordering

• Measure your ESP32's row spacing and compare the pin labels on the silkscreen with your board. ESP_ROW_SPACING in the script sets the spacing.
• Import wled-controller.step into your CAD tool to design an enclosure around it.
• Check the polarity of the DC plug with a multimeter. The board expects centre positive.
• In WLED, set the LED output to GPIO4 and cap the current limit at about 2500 mA for a 3 A supply.

Rev 1.0 build notes (2026-10-14)

Board #1 was hand-soldered and drives a strip without flicker. Problems found on the way, as input for v2:

• Fuse holder under the ESP32. The KEYS3568 holder sits under the overhanging end of the DevKit, so the ESP32 needs a second layer of female headers to clear it. The extra contact made VIN unreliable (the board only worked while the ESP32 was pushed sideways); bending the extra header's VIN leg slightly fixed it. v2: every tall part outside the ESP32 outline, one contact between module and board.
• Cold joints on the power pins. The first pads of both header rows (3V3, VIN, GND) sit on wide power traces and pour; at normal iron temperature the solder did not wet. v2: thermal reliefs on those pads, or solder them at 360-370 °C.
• White solder mask shows flux residue and turns yellow around joints. Pick black or green.
• Lead time. A month of waiting for one board order; order at least 2-3 sets of every part, and more than one board revision in the same order when possible.
• Strip cable. The board should not hang behind the desk: add a 0.5 m JST SM 3-pin extension.

v2 ideas

• at least 4 independent outputs (separate GPIOs, not copies of one signal), possibly room for two ESP32 boards;
• fuse moved away from the module, ideally a main fuse plus protection per output;
• connectors that do not need hand-made pigtails.