Mega wifi R3 - KeirRice/PolarTable GitHub Wiki

atmega2560 esp8266

https://robotdyn.com/mega-wifi-r3-atmega2560-esp8266-flash-32mb-usb-ttl-ch340g-micro-usb.html

AT commands https://nurdspace.nl/ESP8266#AT_Commands

Tutorial http://fab.cba.mit.edu/classes/865.15/people/dan.chen/esp8266/

Firmware https://www.espressif.com/en/support/download/at?keys=&field_type_tid%5B%5D=14