This repository contains firmware for the ESP8266 (Wemos D1 Mini dev board) for a simple LED matrix clock that uses GPS as the time source. See this blogpost for more info.
To flash this firmware open GPS_clock.ino in the Arduino IDE, install ESP8266 Core, then install the required libraries, then compile and flash.
Before flashing the firmware, set the timezone for your location by setting the StandardTimeRule and DaylightTimeRule variables in GPS_clock.ino. Follow the instructions provided by the Timezone library to do this.
If you see errors in the Serial console that EEPROM commit failed, this is due to an issue in the ESP_EEPROM library. See this GitHub issue and implement the fix, then try again. If this is unsuccessful, replace #include <ESP_EEPROM.h> with #include <EEPROM.h>.