ESP3D is firmware for ESP8266 and ESP32 to add wireless control your 3D printer. For me is important print progress and temperatures but you can upload files on SD card and start printing, move motors and send custom commands.
You can get ESP3D here https://github.com/luc-github/ESP3D. I use it with ESP12 and here is my wiring:
Of course ESP part are two pin headers. GPIO0 and GPIO2 are high but for programming I can switch them.
|UART Download Mode||0||1||0|