ESPTimeCast: Build a WiFi LED Matrix Clock and Weather Display

Oct 11, 2026 · 6 min read

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The ESPTimeCast web installer flashes firmware directly from your browser over USB — no IDE or drivers needed.

What You Will Build

ESPTimeCast is a compact desk display that shows the current time, date, and live weather data on an 8×32 MAX7219 LED matrix. It syncs time automatically over NTP, pulls temperature, humidity, and conditions from OpenWeatherMap, and gives you a browser-based interface to control every setting — brightness, timezone, 12/24-hour format, metric or imperial units, custom scroll messages, alarms, countdowns, and more.

Beyond being a clock, the device exposes an HTTP API that works with Home Assistant and other automation tools. An optional browser extension can detect what you are watching on YouTube, Spotify, Twitch, and other platforms and scroll the title across the display in real time. This project is well-suited for a desk, workbench, kitchen counter, or any spot where a glanceable info display would be useful.

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What You Need

Hardware

• One of the officially tested boards:
  • ESP8266: Wemos D1 Mini (USB-C or Micro-USB) or ESP12-F
  • ESP32: ESP32 Dev Module
  • ESP32-C3: SuperMini
  • ESP32-S2: Wemos S2 Mini or Adafruit ESP32-S2 Feather
  • ESP32-S3: WROOM-1 (Camera/SD board), SuperMini, or Zero
• MAX7219 8×32 LED matrix module
• USB cable for initial flashing
• A 5 V power supply (the MAX7219 module runs on 5 V)
• Optional: passive piezo buzzer for audible alarms
• Optional: 3D-printed enclosure (community MAX7219 cases work; an official paid STL is available on Printables and Cults3D)

Software and services

• A Web Serial-compatible browser: Chrome, Edge, Firefox, or Brave
• A free OpenWeatherMap API key (for weather data)
• Your WiFi credentials
• No Arduino IDE, no drivers to install manually

Typical use cases

How It Works

The firmware runs on the Arduino framework and uses the MAX7219 to drive the LED matrix over SPI. On first boot the device starts in Access Point (AP) mode so you can connect to it directly and enter your WiFi details. Once connected to your network it syncs time from NTP servers (with automatic retries and DST handled via the IANA timezone database), then begins polling OpenWeatherMap for weather data.

All configuration is stored in LittleFS flash storage on the board, so settings survive reboots and power cuts. The built-in web server hosts the configuration UI and the /action HTTP API that external tools — Home Assistant, scripts, or the companion browser extension — use to push messages, trigger timers, or change display modes. OTA firmware updates are supported for devices flashed via the web installer, so you can update over WiFi without reaching for a cable.

Wiring the MAX7219 to Your Board

Connect the MAX7219 module to your board using the SPI pins listed below. The module runs on 5 V but accepts 3.3 V logic on DIN, CLK, and CS, so no level shifter is needed for any of the listed boards.

All pin numbers are raw GPIO numbers. ESP8266 D1 Mini boards often label pins D5, D7, D8 — those correspond to GPIO 14, 13, and 15 respectively. Double-check the pin order on your specific MAX7219 module, as labeling and orientation vary between manufacturers.

Flashing and First-Time Setup

Step 1 — Flash the firmware

The recommended method requires no IDE. Open the web installer in Chrome, Edge, Firefox, or Brave:

https://esptimecast.com

Plug your board in via USB, select it in the installer, choose your board model, and click Flash. The whole process takes under a minute.

Step 2 — Connect to the device's access point

After flashing, the board starts in AP mode. On your phone or computer, join the WiFi network named ESPTimeCast using the password 12345678. A captive portal should open automatically. If it does not, navigate to http://192.168.4.1 or http://setup.esp.

Step 3 — Configure WiFi and settings

In the captive portal enter your home WiFi credentials and configure:

• Your OpenWeatherMap API key and location (you can use the "Get My Location" button once connected to WiFi)
• Timezone (IANA format; DST is handled automatically)
• Temperature units (°C or °F), 12/24-hour format, and display preferences

Click Save Settings. The device saves your config to flash, reboots, and connects to your WiFi. It will scroll its local IP address on the display after boot.

Step 4 — Access the web UI

Open http://esptimecast.local or the IP address shown on the display in any browser on your network. From here you can adjust brightness, set alarms, create countdown timers, send custom scroll messages, and trigger OTA firmware updates — all without touching a cable again.

Extending the Build and Known Limitations

Ideas to take it further

• Home Assistant integration: use the /action HTTP API to push sensor readings, automation status, or custom alerts directly to the display.
• Companion browser extension: install the ESPTimeCast Companion extension from the Chrome Web Store (firmware v1.5.0 or later required) to automatically scroll now-playing titles from YouTube, Spotify, Twitch, Prime Video, Vimeo, Dailymotion, and SoundCloud. The extension also lets you send messages and control brightness from a browser popup without opening the web UI.
• Nightscout glucose display: the firmware supports displaying blood glucose readings in mg/dL or mmol/L, alternating with weather data — useful for diabetic makers.
• Buzzer alerts: wire a passive piezo buzzer to your board to get audible alarm and timer notifications.
• 3D-printed case: search for "MAX7219 case" on Printables or Cults3D for free community-designed enclosures that fit the standard 8×32 module, or purchase the official ESPTimeCast STL files from either platform.
• Cast to multiple devices: the companion extension can broadcast to more than one ESPTimeCast unit on the same network simultaneously.

Limitations to keep in mind

• Weather data requires a free OpenWeatherMap API key; without one, only time and date are displayed.
• OTA updates are fully supported only for devices flashed via the web installer; manually compiled builds may have limited OTA support.
• The "Get My Location" button and external links in the setup portal do not work while the device is in AP mode — connect to your WiFi first.
• Boards other than those in the tested list may work if they use the same chip families, but SPI pin mapping and USB behavior can differ and will need manual verification.

Facts in this article come from the project's public README and GitHub metadata at the time of writing. Images belong to their respective owners and link back to the original source.