About 8 years ago I created wall clock with bluetooth synced time. Ok, its enough. Lets go to modern world with universal wifi driven devices! Today I trashed old AVR microcontroller from wall clock and used esp8266. 8 MHz and 80MHz… feel difference! At first steps I used ESP-12 NodeMCU module to develop and debug firmware. You can do final device with this module if you absolutely novice in mcu programming, if not you can do it with ESP-01 module.
Do not forget turn on SPIFFS 1M option in Arduino IDE. At first run device will turn on own AP with configuring interface, connect it to your wifi network. With ESP-01 modules vendored by Puya problem, SPIFFS is not accessible! Saving parameters works only with ESP-12. This problem must be solved in future SDK versions.
Download source code
Wiring for NodeMCU ESP-12 development board
Wiring for ESP-01 board
Final device after moving to ESP-01
Checkout my another clock projects:
№ 8618 В разделе Electronics от March 25th, 2018,
Ноутбук Asus K96VB, квадратный блок питания. Разбор склеенного корпуса БП и замена конденсаторов.