thank you very much. this directly killed my strategy using occu on hass.io. I will stay on this gpio device and build a raspberrymatic to control my homematic ip or even stay with my homematic ip accesspoint as it is already there and functioning.
Go for raspberrymatic. The access point only works with the Homematic IP cloud which means it depends on internet connection. With raspberrymatic it’ll work offline, too.
Just try to do all automation in home assistant to reduce complexity of your set-up. I’m still trying to figure out how to move my thermostat automation from raspberrymatic to hass.io.
yeah, I am currently searching for a solution to run home assistant and raspberrymatic on the same raspberry… that would be awesome… 
Edit: I think I found a way: I will install hassbian (as far as I found it is based on raspbian stretch) and then go with piVCCU for HomematicIP control. If that works I am happy!
Edit2: got it running: installed hassbian and then installed piVCCU with ccu3. waiting for my gpio module now and then everything should be done and running with one raspberry… 
@rotbarsch not sure if you get notifications if I edit my post, so if you are interested - re-read it…
Didn’t know piVCCU was a thing. Quite interesting.
Is there any useful tutorial for the OCCU addon available?