http://www.fhemwiki.de/wiki/Raspberry_Pi

sudo apt-get install perl libdevice-serialport-perl
sudo apt-get install libio-socket-ssl-perl libwww-perl
wget http://fhem.de/fhem-5.5.deb
dpkg -i fhem-5.5.deb
apt-get install -f

go to interface:
http://pidor:8083/fhem

how to make a button:
https://groups.google.com/forum/#!topic/fhem-users/1eQJ_Q4Evo4
define MyBtn FS20 9999 99
attr MyBtn dummy
define MyNotify notify MyBtn "/local/bin/mypgm %"