I have just published my version of the EMS interface. This galvanically separates the EMS bus side from the microcontroller side. The EMS bus side is powered from the bus, while the other side is powered from the microcontroller. Optocouplers are used for the separation.
The operation so far (several days) is completely problem-free and the data communication is 100% reliable.
Hopefully someone will be interested.
Heya, I just built one of your boards and got everything connected up to homeassistant. So far so good! Thanks for sharing the design. I was wondering if you had an stl for the case that you show in the pictures on github?