KNX with Raspberry Pi – Install Raspbian Part 1

  • Download Raspbian Stretch from
  • Find required device name
    df -h
    /dev/mmcblk0p1 29G 32K 29G 1% /media/marc/1FAB-7

  • Umount device
    sudo umount /dev/mmcblk0p1

  • Copy image to SD card
    dd bs=4M if=2017-09-07-raspbian-stretch-lite.img of=/dev/mmcblk0p1

  • Mount image to activate ssh
    mount /dev/mmcblk0 /mnt
    touch /mnt/ssh

  • Connect raspberry to network and power up; Find IP address of Raspberry
    nmap -sP
    Nmap scan report for (

  • Enlarge filesystem by logging into pi with username pi and password raspbian
    ssh pi@
    sudo raspi-config

  • Select 7) advanced options
  • Select a1) expand filesystem
  • Bouldering in Tenerife


    We have been searching for good place for bouldering in autumn/winter and decided to travel to Tenerife. Tenerife has a couple of spots that are well suited for bouldering.


    • Car: Renting a car in Tenerife is very cheap.
    • Crashpad: It is possible to rent a crashpad at Tenerife Outdoor. More information is provided on their Roxtar page.

    Boulder Spots

    Arico Nuevo

    Provides a lot of boulder possibilites. A guidebook with detailed information about all boulders can be obtained from the Tenerife Outdoor shop. They provide you with a link to the pdf guide that can be viewed on your smartphone/tablet. Since the pdf file is of very high quality I would recommend you to visit the shop and buy something there to support them.

    We spent four days in the barranco of Arico Nuevo.


    Arico Viejo

    The famous climbing spot of Arico Viejo provides also many boulder problems. As far as I know, there is no guidebook available.

    Personally, I liked Arico Viejo very much. The baranco is very nice.




    The Teide national park provides also some bouldering possibilities. There is the so called Tortuga. This is a pretty high boulder, I would estimate it on 5 meters.




    Bouldering in Varazze

    After staying in Chiavari, we decided to go a bit bouldering in Varazze. The number of boulder problems is amazing. All of the problems are described in this guidebook. For each crag at least one picture is provided.

    Unfortunately, the weather was not that good. It did not rain, but the humidity was very high due to the clouds coming from the sea. Therefore, the rocks were very slippery in the Potala area. Might be that we have decided on the wrong season. This might be the reason for being alone on the craigs. The guidebooks describes parking spaces, which revealed to be more of being single parking lots.

    Being in Varazze and in Fontainebleau within the same year, I personally prefer Fontainebleau. Let me point out the differences:

    • Terrain: Varazze is in a very hilly terrain, whereas Fontainbleau is pretty plain.
    • Gound: Varazze is more in forest with a soil ground. Fontainbleau has more sand
    • Parcours: Fontainbleau has thie nice kind of parcours that I personally like very much.
    • Kids: For our 10 months old son, Fontainebleau was a bit less dangerous. In particular the chestnut trees in Varazze and the spiky shells of their fruits are not that good for crawling around.

    P1080172 (1024x768)Varazze Potala Sector

    Italian Riviera – Chiavari

    We recently stayed in the Olive Press Lodge in Chiavari. It was a very cozy place and allowed us to relax. We arrived during the harvesting of olives, which seems to be a very hard and labour-intensive business. The owners of the lodge sold freshly pressed home-made olive-oil to us. Very delicious.

    From the lodge it takes only 10 to 15 minutes to the city center of Chiavari, which is a small, but enjoyable town.

    We also visited Cinque Terre. Unfortunately, it was not possible to walk from city to city with strollers. We thought it must be possible to walk from Riomaggiore to Manarola. But the path is closed since 2013. I suppose it will not be opened again.

    Pictures can be found here.

    Code Evasion

    Gerard Holzmann recently published an article on “Code Evasion” in IEEE Software. He showed a couple of examples how error handling increases the complexity of reading and understand code, but also the increased potential for bugs. This does not mean to remove all error handling, but to give an extra thought.

    In my opinion he is perfectly right. Writing proper error handling code is a big challenge. Ignoring it at all and let program crash is not always an option.

    Using exceptions instead of return values can increase the readability. It does not mitigate the complexity of error handling and proper reactions. IMHO one of the advantages of exceptions – at least in programming languages like C++ and C# – is that they can bubble up and you can catch them some where very different. Probably at a place where you can react properly.

    Creating presentations with pictures

    Recently, I was wondering where to get pictures for a public presentation. In particular it was important to have pictures that are free and that do not cause any licensing issues.

    This page gives a pretty good overview of pages with free pictures: