Gerne, ich habe mich dabei hauptsächlich einen einen Beitrag von space4u gehalten:
(https://community.openhab.org/t/openhabian-hassle-free-rpi-image/13379/490)
(mini)Howto install the eq3 “HM-MOD-RPI-PCB” module on Raspberry 2 with openHABian,
All steps was run after a clean OpenHABian installation…
01 | update the system
sudo apt-get update
sudi apt-get upgrade
sudo rpi-update
02 | edit file and add the line
sudo vim /boot/config.txt
enable_uart=1
03 | edit file and remove the following entrys
sudo vim /boot/cmdline.txt
console=ttyAMA0,115200 kgdboc=ttyAMA0,115200 console=tty1
04 | edit file and remove the following line
sudo vim /etc/inittab
T0:23:respawn:/sbin/getty -L ttyAMA0 115200 vt100
05 | disable getty service
sudo systemctl disable getty@.service
06 | reboot the system
sudo reboot
07 | check whether service is really no longer running, it is important that we do not receive any output
ps -A | grep getty
output: nothing
08 | check the ttyAMA0 rights
ls -l /dev/ttyAMA0
output: crw-rw---- 1 root dialout 204, 64 Jan 15 00:02 /dev/ttyAMA0
09 | run openhabian-config and execute entrys:
sudo openhabian-config
01 | Update
02 | Basic Setup
03 | Java 8
04 | openHAB 2
11 | Optional: Homegear
20 | Serial Port
- uncheck [ ] 1 Disable serial console
10 | reboot the system
sudo reboot
11 | edit file and remove the # symbole in the following lines
sudo vim /etc/homegear/families/homematicbidcos.conf
[HomeMatic Wireless Module for Raspberry Pi]
id = My-HM-MOD-RPI-PCB
deviceType = hm-mod-rpi-pcb
device = /dev/ttyAMA0
responseDelay = 95
gpio1 = 18
12 | restart homegear service
sudo /etc/init.d/homegear restart
13 | now you can pair homematic devices with homegear
14 |now you can install the homematic binding in openHAB
Noch eine weitere - fast (es gibt einen kleinen Unterschied in der cmdline.txt) identische - Anleitung, die mir sehr geholfen hat:
https://doc.homegear.eu/data/homegear-homematicbidcos/configuration.html#communication-modules
HM-MOD-RPI-PCB scheint übrigens etwas sensibel zu sein; ich wollte meinen Pi3 über WLAN verbinden - und schon hatte ich wieder den alten Fehler - also seid vorsichtig was ihr macht. 
cu