Compile it yourself

Install the Arduino IDE and the ESP32 board package

Download the Arduino IDE from arduino.cc/en/software and install it. Then add Espressif's ESP32 board package:

1. Open File → Preferences (Windows/Linux) or Arduino IDE → Settings (macOS).
2. In "Additional boards manager URLs", add:

   https://raw.githubusercontent.com/espressif/arduino-esp32/gh-pages/package_esp32_index.json

3. Open Tools → Board → Boards Manager, search for esp32 (by Espressif Systems), and install it.

Install the required libraries

Open Tools → Manage Libraries... and install each of these (search by name, exact match on the first result). This is the full list — the v2.0 board's physical button and speaker don't add anything here, both run on APIs already built into the core ESP32 toolchain.

Patch the WebSockets library (one line, required)

The WebSockets library always appends its own default User-Agent header when building the handshake — even when the caller (this firmware) already supplied one. That duplicate header corrupts the handshake chess.com expects, and the connection drops right after the first frame with no useful error.

Find WebSocketsClient.cpp inside your Arduino libraries folder (typically Documents/Arduino/libraries/WebSockets/src/) and locate the sendHeader() function. Skip appending the default User-Agent line when the caller already provided extra headers containing one. The exact patch and a full explanation of the bug are documented at the top of LiveGameClient.cpp in the firmware source — open that file for the precise before/after code.

Get the code

Clone or download the firmware from GitHub:

git clone https://github.com/ivolanski/IvoChess-Clock.git

Open IvoChess_Clock.ino in the Arduino IDE — it'll load the whole sketch (all the .h/.cpp files sit alongside it and load together).

Compile and upload

Click Upload (or Ctrl/Cmd+U). First compile takes a few minutes; the ESP32 core and libraries above need to build. Once it's done, the board resets and starts running automatically.

To confirm it's alive, open Tools → Serial Monitor at 115200 baud — you should see startup logs, including whether it found a saved Wi-Fi network or started its own setup hotspot.