Desktop Clock

A desktop digital clock built using an ESP32 microcontroller, MAX7219 led matrix display, and Arduino lang.

• Syncs time from an Internet time server (NTP) on boot-up
• Syncs time once a day from Internet servers to prevent drift.
• Connects to WiFi just before Internet time sync and then disconnects when done to conserve power
• Automatically adjusts UK daylight saving

Design Principles

• Optimise for power consumption.
  • Minimise external service dependencies.
  • JIT connect to WiFi for external calls. Disconnect immediately after.
• Minimise third part library dependencies.

Dependencies

• SPI.h
• WiFi.h
• LedMatrix.h MAX7219 library. Forked from @nhatuan84 and modified to support the max7219 hardware variation I have.
• time.h ref, source - standard C library.
  • Not using TimeLib.h by Michael Margolis because we don't need all that functionality. Github, Docs

Contributions

Note: the following has only been tested on macOS.

Third-party libraries

• Open Arduino IDE > preferences, note the sketchbook location
• cd <sketchbook location>/libraries
• git clone https://github.com/janaka/esp32-led-matrix

Tool Dependencies

Just the Arduino IDE Arduino IDE

Board manager URLs - one off config

• http://arduino.esp8266.com/stable/package_esp8266com_index.json
• https://dl.espressif.com/dl/package_esp32_index.json

Using VS Code

Arduino VS Code extension Depends on the Arduino IDE

Configure WiFi

• Rename 1.wifi_config.tmp to 1.wifi_config.ino
  • NOTE: the 1.wifi_config.ino is in .gitignore. DO NOT check-in
• Add your wifi details.

Uploading a sketch in VS Code

• Serial port should show as /dev/tty.SLAB_USBtoUART.
  • this needs the SLAB driver to be install
• Upload from VS Code: option + command + u.

Debug

Look at the serial monitor output for information using the Arduino IDE

Hardware wiring diagram

TODO: diagram

• CS -> GPIO 15
• CLK -> GPIO 14
• DIN -> GPIO 12

ESP-WROM-32 devkit pinout schema

You may have a different variation of the ESP32 dev board. Check before connecting.