Table Digital Clock Design by little experienced me.

[JustVic]

I want to make cheap wifi digital clock. I plan to use MAX7219 led matrix(it is cheap, big enough and bright), atmega328 and esp8266. I don't like esp8266 because it requires firmware blobs or esp-open-sdk that is very hard to build and setup it requires legacy libraries, I want it to be maximum open source friendly. I wrote firmware draft for atmega328 that recieves text by UART and scroll it on LED matrix. Atmega328 also reads time from RTC clock chip and show it. I would like to have the function of sending any text message to this clock. Curently I use modified marqee scroller clock firmware(https://github.com/Qrome/marquee-scroller) for ESP8266(ESP sends text by UART to Atmega328) it is under MIT license as I understand It is possible to use even in commercial purposes, but I plan rewrite it. I plan to power it from maybe usb-c port connector. All my firmwares will be open source. Is this a good plan or a crazy one?

Tell me how would you make such a device? Which chips would you use?
Basic requirements:
--The most open SDK as in avr-gcc. And preferably the same ease of use.
--Cheap components.
--Preferably Wi-fi.
--It is undesirable to use the Arduino IDE, it is better to use pure C/C++ with Makefiles.

Which interfaces should I output separately on the circuit for debugging or in-circuit firmware flashing of microcontrollers?

Main function is show time and recieve any text from wifi and scroll it.
Sorry for the large amount of text and a bunch of questions.

 

[netrunner_sw]

You are stumbling close to making a cheap and very cool project here.

With WLED https://kno.wled.ge/ you can control an array of WS2812 RGB diodes from an ESP32. Programming the ESP32 is done directly from their website (no software needed) and you can make it a clock (and 1000-times more things). Configured from the ESP32's built-in configuration website. Plugins for RTC and mic are available.

(warning WLED is very addictive project)

https://www.aliexpress.us/item/3256803715519232.html You want the 8x32
https://www.aliexpress.us/item/3256805517875317.html micro-USB or USB-C
https://www.aliexpress.us/item/3256805372202568.html You want DS3231 MINI (battery included)
https://www.aliexpress.us/item/3256805747093872.html I2S mic, from "cool project" to "OMG!"

And a normal USB-charger to get 5V power.