I have been pretty busy with work lately so I haven't had much time to work on this. I work in IT but not in development so it's slow going making this thing. I'll try to get something uploaded to github soon
I have not been able to do much on this still. I have a repo on github which is a work in progress. The aim is to get a web interface on the rpi so it easy to upgrade the firmware, but that's a while away (really busy with work). There is info on how to make a cable so at least you can make one up and upgrade your firmware.
I already have a Wifi module, but I find it interesting to be able to communicate with the speidel also without Wifi.