Two cornhole boards,
built from nothing.

The short version

Fifty-seven seconds, start to finish.

The build

Nothing here was bought pre-cut. The whole board was modelled first, which meant the cut list came out of the CAD rather than out of a guess.

How it went

The look came first

The face isn't paint or vinyl — it's alternating hardwood. That meant the design decision had to be made before the glue-up, on paper.

Cut list

Per board. All 3/4" stock unless noted. Item numbers match the Fusion drawing above.

Electronics

One ESP32 per board, one USB power bank, no level shifter, no separate controller. Every part below is duplicated across the two boards.

Pin assignments

Half the ESP32 header is unusable, so this map is less obvious than it looks — see what went wrong.

Wiring

One power bank per board feeds a single junction. Everything hangs off that junction in parallel — nothing daisy-chains through the ESP32.

The IR receiver is the exception: it runs off the ESP32's 3.3 V pin rather than the 5 V rail, so its output can never exceed the 3.3 V GPIO limit. The emitter runs on 5 V.

LED chain

One continuous data chain, three power injection points. The controller sees a single long strip.

GPIO 16 ──[330 Ω]──> ring DIN  (pixels 0–59)
                         │
                    ring DOUT
                         │
                         └──> perimeter DIN  (pixels 60–268)

power injected in parallel at 3 points, all from the junction:
   • ring
   • perimeter start
   • perimeter end
1000 µF cap across 5 V / GND at the injection point

The first physical LED is a sacrificial pixel — never used for display. It absorbs any weakness in the 3.3 V data level so a level shifter isn't needed. On this hardware the ring drove cleanly straight off the ESP32 with no shifter at all; if a longer run ever flickers, a 74AHCT125 is the fallback.

Colour order is GRB. Brightness is capped in firmware to stay inside the power bank's shared 3 A budget — 269 LEDs at full white would ask for far more than that.

Firmware

Arduino IDE, FastLED and TFT_eSPI. One sketch, flashed to both boards.

What it does

• Stars vs Stripes scoreboard, 0–21, clamped.
• Five arcade buttons, active low on internal pull-ups, ~250 ms debounce. Cancellation scoring stays a human call.
• IR break-beam fires a celebration when a bag drops through — display flash plus a full LED sweep. Detection is a celebration, not a score.
• Power-up animation: gold colour wipe, two rainbow spins, settle to a dim blue idle.
• Wireless score sync between boards over ESP-NOW.
• Over-the-air firmware updates, behind a deliberate toggle.

How the sync works

ESP-NOW, on a broadcast peer — no MAC addresses hardcoded anywhere. That means an ESP32 can be swapped out without touching a line of firmware. Each packet carries the sender ID, both scores, a sequence byte and an event type.

Crucially, every packet is full state, not a delta. If one goes missing, the next event silently repairs it — there's no drift to accumulate and no resync handshake to write. The receive callback only sets flags and copies data; it never touches the LEDs or the display directly.

Flashing over the air

toggle OTA mode:  hold Team1 + and Team1 − together
                  (boots OFF every time — never persisted)

Mac and board on the same 2.4 GHz SSID and the same subnet
discovery/handshake on UDP 3232

  dns-sd -B _arduino._tcp              # is the board advertising?
  dns-sd -G v4 cornhole-board-B.local  # resolve to an IP
  ping cornhole-board-B.local

Arduino IDE → Tools → Port → Network Ports → cornhole-board-A
Partition scheme: Minimal SPIFFS (1.9 MB APP with OTA)

Only ever put one board in OTA mode at a time — not because it breaks, but because it's too easy to flash the wrong one. And anything that touches the radio init goes over USB: OTA can't fix a failed OTA.

What went wrong

The parts worth knowing before you start, rather than after.

Gallery

Daylight and dark.