Hello,
i would like to use this board:
i already use this board before with code on the Mega and AT Firmware on the esp.
now i flashed esphome to the ESP and i set the switches back
what would i need to get the communication going?
Well you can program the ESP part with ESPHome but it’ll give you only access at peripherals connected straight at ESP ! For rest you’ll still need to put a program in the Mega chipset and get it to communicate with the ESP 
Unhappy there are no schematics of board on your link all in german 
Hi, thanks for your answer. I found some more documents: