Archive for category N3RD

How to weigh your cat! – the IoT version

This is Leela. She is a 7 year old lilac white British short hair cat that lives with us. Leela had a sister who used to live with us as well but she developed a heart condition and passed away last year. Witnessing how quickly such conditions develop and evaluate we thought that we can do something to monitor Leelas health a bit to just have some sort of pre-alert if something is changing.

Kid in a Candystore

As this Internet of Things is becoming a real thing these days I found myself in a candy store when I’ve encountered that there are a couple of really really cheap options to get a small PCB with input/output connectors into my house WiFi network.

One of the main actors of this story is the so called ESP8266. A very small and affordable system-on-a-chip that allows you to run small code portions and connect itself to a wireless network. Even better it comes with several inputs that can be used to do all sorts of wonderful things.

And so it happened that we needed to know the weight of our cat. She seemed to get a bit chubby over time and having a point of reference weight would help to get her back in shape. If you every tried to weigh a cat you know that it’s much easier said than done.

The alternative was quickly brought up: Build a WiFi-connected scale to weigh her litter box every time she is using it. And since I’ve recently bought an evaluation ESP8266 I just had to figure out how to build a scale. Looking around the house I’ve found a broken human scale (electronics fried). Maybe it could be salvaged as a part donor?

A day later I’ve done all the reading on that there is a thing called “load-cell”. Those load cells can be bought in different shapes and sizes and – when connected to a small ADC they deliver – well – a weight value.

I cracked the human scale open and tried to see what was broken. It luckily turned out to have completely fried electronics but the load-cells where good to go.

Look at this load cell:


That brought down the part list of this project to:

  • an ESP8266 – an Adafruit Huzzah in my case
  • a HX711 ADC board to amplify and prepare the signal from the load-cells
  • a human scale with just enough space in the original case to fit the new electronics into and connect everything.

The HX711 board was the only thing I had to order hardware wise – delivered the next day and it was a matter of soldering things together and throwing in a small Arduino IDE sketch.

My soldering and wiring skills are really sub-par. But it worked from the get-go. I was able to set-up a small Arduino sketch and get measurements from the load-cells that seemed reasonable.

Now the hardware was all done – almost too easy. The software would be the important part now. In order to create something flexible I needed to make an important decision: How would the scale tell the world about it’s findings?


Two basic options: PULL or PUSH?

Pull would mean that the ESP8266 would offer a webservice or at least web-server that exposes the measurements in one way or the other. It would mean that a client needs to poll for a new number in regular intervals.

Push would mean that the ESP8266 would connect to a server somewhere and whenever there’s a meaningful measurement done it would send that out to the server. With this option there would be another decision of which technology to use to push the data out.

Now a bit of history: At that time I was just about to re-implement the whole house home automation system I was using for the last 6 years with some more modern/interoperable technologies. For that project I’ve made the decision to have all events (actors and sensors) as well as some additional information being channeled into MQTT topics.

Let’s refer to Wikipedia on this:

“MQTT1 (formerly MQ Telemetry Transport) is an ISO standard (ISO/IEC PRF 20922) publish-subscribe-based “lightweight” messaging protocol for use on top of the TCP/IP protocol. It is designed for connections with remote locations where a “small code footprint” is required or the network bandwidth is limited. The publish-subscribe messaging pattern requires a message broker. Thebroker is responsible for distributing messages to interested clients based on the topic of a message. Andy Stanford-Clark and Arlen Nipper of Cirrus Link Solutions authored the first version of the protocol in 1999.”

Something build for oil-pipelines can’t be wrong for your house – can it?

So MQTT uses the notation of a “topic” to sub-address different entities within it’s network. Think of a topic as just a simple address like “house/litterbox/weight”. And with that topic MQTT allows you to set a value as well.

The alternative to MQTT would have been things like WebSockets to push events out to clients. The decision for the home-automation was done towards MQTT and so far it seems to have been the right call. More and more products and projects available are also focussing on using MQTT as their main message transport.

For the home automation I had already set-up a demo MQTT broker in the house – and so naturally the first call for the litterbox project was to utilize that.

The folks of Adafruit provide the MQTT library with their hardware and within minutes the scale started to send it’s measurements into the “house/litterbox/weight” topic of the house MQTT broker.

Some tweaking and hacking later the litterbox was put together and the actual litterbox set on-top.

Since Adafruit offers platform to also send MQTT messages towards and create neat little dashboards I have set-up a little demo dashboard that shows a selection of data being pushed from the house MQTT broker to the MQTT broker.

These are the raw values which are sent into the weight topic:

You can access it here:

So the implementation done and used now is very simple. On start-up the ESP8622 initialises and resets the weight to 0. It’ll then do frequent weight measurements at the rate it’s configured in the source code. Those weight measurements are being monitored for certain criteria: If there’s a sudden increase it is assumed that “the cat entered the litterbox”. The weight is then monitored and averaged over time. When there’s a sudden drop of weight below a threshold that last “high” measurement is taken as the actual cat weight and sent out to a /weight topic on MQTT. The regular measurements are sent separately to also a configurable MQTT topic.

You can grab the very ugly source code of the Arduino sketch here: litterbox_sourcecode

And off course with a bit of logic this would be the calculated weight topic:

Of course it is not enough to just send data into MQTT topics and be done with it. Of course you want things like logging and data storage. Eventually we also wanted to get some sort of notification when states change or a measurement was taken.

MQTT, the cloud and self-hosted

Since MQTT is enabling a lot of scenarios to implement such actions I am going to touch just the two we are using for our house.

  1. We wanted to get a push notification to our phones whenever a weight measurement was taken – essentially whenever the cat has done something in the litterbox. The easiest solution: Set-Up a recipe on If This Than That (IFTTT) and use PushOver to send out push notifications to whatever device we want.
  2. To log and monitor in some sort of a dashboard the easiest solution seemed to be Adafruits offer. Of course hosted inside our house a combination of InfluxDB to store, Telegraf to gather and insert into InfluxDB and Chronograf to render nice graphs was the best choice.

Since most of the above can be done in the cloud (as of: outside the house with MQTT being the channel out) or inside the house with everything self-hosted. Some additional articles will cover these topics on this blog later.

There’s lots of opportunity to add more logic but as far as our experiments and requirements go we are happy with the results so far – we now regularly get a weight and the added information of how often the cat is using her litterbox. Especially for some medical conditions this is quite interesting and important information to have.

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the xenim streaming network SONOS integration now plays recent shows!




Since I am frequently using the xenim streaming network service but I was missing out on the functionality to replay recent shows. With the wonderful functionality of Re-Live made available through ReliveBot  I have now added this replay feature and I am using it a lot since.

Within the SONOS controller app it looks like this:

Screen Shot 2015-07-31 at 14.22.13


To set-up this service with your SONOS set-up just follow the instructions shown here: a new Music Service for SONOS

Source 1: xenim streaming network
Source 2: ReliveBot
Source 3: Download the Custom Service
Source 4: a new Music Service for SONOS

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Stitch Panoramic Views like a pro

I am using this for more several years now. Even though all my workflow happens on Macintosh computers these days I’ve kept this tool in my toolbox: Microsoft Image Composite Editor.

Screen Shot 2015-03-08 at 19.00.47


Now after along while with the 1.0 version Microsoft Research decided to release a new version of the free tool with even more features and a new streamlined user interface. This is so much better than before.

“Image Composite Editor (ICE) is an advanced panoramic image stitcher created by the Microsoft Research Computational Photography Group. Given a set of overlapping photographs of a scene shot from a single camera location, the app creates a high-resolution panorama that seamlessly combines the original images. ICE can also create a panorama from a panning video, including stop-motion action overlaid on the background. Finished panoramas can be shared with friends and viewed in 3D by uploading them to the Photosynth web site. Panoramas can also be saved in a wide variety of image formats, including JPEG, TIFF, and Photoshop’s PSD/PSB format, as well as the multiresolution tiled format used by HD View and Deep Zoom.”

Source 1:

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I wish there was: cheap network microphones with open source speech recognition

I was on a business trip the other day and the office space of that company was very very nice. So nice that they had all sorts of automation going on to help the people.

For example when you would run into a room where there’s no light the system would light up the room for you when it senses your presence. Very nice!

There was some lag between me entering the room, being detected and the light powering up. So while running into a dark room, knowing I would be detected and soon there would be light, I shouted “Computer! Light!” while running in.

That StarTrek reference brought an old idea back that it would be so nice to be able to control things through omnipresent speech recognition.

I am aware that there’s Siri, Cortana, Google Now. But those things are creepy because they involve external companies. If there are things listening to me all day every day, I want them to be within the premise of the house. I want to know exactly down to the data flow what is going on and sent where. I do not want to have this stuff leave the house at any times. Apart from that those services are working okayish but well…

Let alone the hardware. Usually the existing assistants are carried around in smart phones and such. Very nice if you want to touch things prior to talking to them. I don’t want to. And no, “Hey Siri!” or “OK Google” is not really what I mean. Those things are not sophisticated enough yet. I was using “Hey Siri!” for less than 24 hours. Because in the first night it seemed to have picked up something going on while I was sleeping which made it go full volume “How can I help!” on me. Yes, there’s no “don’t listen when I am sleeping” thing. Oh it does not know when I am sleeping. Well, you see: Why not?

Anyway. What I wish there was:

  • cheap hardware – a microphone(-array) possibly to put into every room. It either needs to have WiFi or LAN. Something that connects it to the network. A device that is carried around is not enough.
  • open source speech recognition – everything that is collected by the microphone is processed through an open source speech recognition tool. Full text dictation is a bonus, more importantly heavy-duty command recognition and simple interactions.
  • open source text to speech – to answer back, if wanted

And all that should be working on a basic level without internet access. Just like that.

So? Any volunteers?

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31st Chaos Communication Congress


Like every year the Chaos Communication Congress gathered thousands of people in one place between the Christmas-Holidays and NewYears.

Since I was out-of-order this year to attend I’ve opted for the Attending-by-Stream option. All Lectures are live-streamed by the awesome CCC Video Operations Center (C3VOC) and made available as recordings afterwards.

Since the choice of topics is enormous here are some I can recommend:

Source 1:
Source 2:
Source 3:
Source 4:


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Infinitely Bioshocking Panoramic Views pt. 2

Screen Shot 2014-12-20 at 15.46.07_stitch



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Infinitely Bioshocking Panoramic Views

Here are just two of the panoramic images I’ve made while playing through BioShock Infinite this year. Gorgeous art!



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in case of emergency: spoof your MAC address



There have been several occasions in the past years that I had to quickly change the MAC address of my computer in order to get proper network connectivity. May it be a corporate network that does not allow me to use my notebook in a guest wifi because the original MAC address is “known” or any other possible reasons you can come up with…

Now this is relatively easy on Mac OS X – you can do it with just one line on the shell. But now there’s an App for that. It’s called Spoof:


“I made this because changing your MAC address in OS X is harder than it should be. The Wi-Fi card needs to be manually disassociated from any connected networks in order for the change to apply correctly – super annoying! Doing this manually each time is tedious and lame.

Instead, just run spoof and change your MAC address in one command. Now for Linux, too!”


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Formula 1 is past – now it’s drone racing!

As racing cars with petrol engines gets more and more uninteresting for the masses and even Formula 1 faces competition by Formula E.

Now having humans inside cars racing a wide track is one thing, but using relatively cheap but extremely high-tech multi-copters with first-person-view cameras mounted on them and flown by crazy guys sitting next to the “racing track” is the next big thing!

As you can see it basically looks like the Endor-scenes from Star Wars. In fact it does look so interesting that I am tempted to try it myself…

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blast from the past: a Console Framework for .NET

“Console framework is cross-platform toolkit that allows to develop TUI applications using C# and based on WPF-like concepts.”


Source 1:
Source 2:
Source 3:

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when you’re working late: grant your eyes a rest

“Ever notice how people texting at night have that eerie blue glow?

Or wake up ready to write down the Next Great Idea, and get blinded by your computer screen?

During the day, computer screens look good—they’re designed to look like the sun. But, at 9PM, 10PM, or 3AM, you probably shouldn’t be looking at the sun.

f.lux fixes this: it makes the color of your computer’s display adapt to the time of day, warm at night and like sunlight during the day.

It’s even possible that you’re staying up too late because of your computer. You could use f.lux because it makes you sleep better, or you could just use it just because it makes your computer look better.”

Bildschirmfoto 2014-09-27 um 12.58.33


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Unlock PDF files

The next time you stumble across a PDF file with security and not allowing you to print or copy/paste.

Do this:

qpdf –decrypt

“QPDF is a command-line program that does structural, content-preserving transformations on PDF files. It could have been called something like pdf-to-pdf. It also provides many useful capabilities to developers of PDF-producing software or for people who just want to look at the innards of a PDF file to learn more about how they work.

QPDF is capable of creating linearized (also known as web-optimized) files and encrypted files. It is also capable of converting PDF files with object streams (also known as compressed objects) to files with no compressed objects or to generate object streams from files that don’t have them (or even those that already do). QPDF also supports a special mode designed to allow you to edit the content of PDF files in a text editor. For more details, please see the documentation links below.

QPDF includes support for merging and splitting PDFs through the ability to copy objects from one PDF file into another and to manipulate the list of pages in a PDF file. The QPDF library also makes it possible for you to create PDF files from scratch. In this mode, you are responsible for supplying all the contents of the file, while the QPDF library takes care off all the syntactical representation of the objects, creation of cross references tables and, if you use them, object streams, encryption, linearization, and other syntactic details.

QPDF is not a PDF content creation library, a PDF viewer, or a program capable of converting PDF into other formats. In particular, QPDF knows nothing about the semantics of PDF content streams. If you are looking for something that can do that, you should look elsewhere. However, once you have a valid PDF file, QPDF can be used to transform that file in ways perhaps your original PDF creation can’t handle. For example, programs generate simple PDF files but can’t password-protect them, web-optimize them, or perform other transformations of that type.”

Source 1:
Source 2:

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Shaders in your browser

“Shadertoy is the first application to allow developers all over the globe to push pixels from code to screen using WebGL since 2009.

This website is the natural evolution of that original idea. On one hand, it has been rebuilt in order to provide the computer graphics developers and hobbyists with a great platform to prototype, experiment, teach, learn, inspire and share their creations with the community. On the other, the expressiveness of the shaders has arisen by allowing different types of inputs such as video, webcam or sound.”

Bildschirmfoto 2014-09-27 um 12.29.04

Source 1:

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a new Music Service for SONOS: xenim streaming network

I am a frequent podcast live-stream listener. And being that I am enjoying the awesome service called xenim streaming network.

Bildschirmfoto 2014-08-19 um 21.03.21

Any Podcast producer can join the xsn and with that can live-stream his own Podcast while recording. It’s CDN is based on voluntarily provided resources and pretty rock-solid as far as my experience with it goes.

Since I am a frequent user of this – and I’ve got that gorgeous SONOS hardware scattered around my house – I thought I need to have that service integrated into my SONOS set.

The SONOS system knows the concept of “Music Services”. There are quite a lot of them but xsn is missing. But SONOS is awesome and they got an API!

Unfortunately the API documentation is hidden behind a NDA wall so that would be a no-go. What’s not hidden is what the SONOS controllers have to discuss with all the existing services. Most of the time these do not use HTTPS so we’re free to listen to the chatters. I did just that and was able, for the sake of interoperability, to reverse engineer the SONOS SMAPI as far as it is necessary to make my little xsn Music Service work.

As usual you can get the source-code distributed freely through Github. If you’re not into that sort of compiling and programming things, you are invited to use my free-of-charge provided service. To set it up on your home SONOS just follow these simple steps:

Step 1: Start your SONOS Controller Application and find out the IP address of your SONOS.

Click on “About My Sonos System” and check the IP address written next to the “Associated ZP”.

Screen Shot 2014-08-19 at 19.45.56

Step 2: Add the xsn Music Service.

By opening a browser window and browsing to: http://<your-associated-zp-ip>:1400/customsd.htm

When you’re there – fill out the fields as below. The SID is either 255, or if you used that previously, something between 240-253. The service name is “xenim streaming network”. The Endpoint URL and Secure Endpoint URL both are

Set the Polling interval to 30 seconds. Click on the Anonymous Authentication SOAP header policy and you’re good to go. Click on “send” to finish.

Bildschirmfoto 2014-08-19 um 21.16.27

Step 3: Add the new Music Service to your SONOS Controller.

Click on “Add Music Services” and click through until you see “xenim streaming network”. Add the service and you’re set!

p.s.: It’s normal that the service icon is a question mark.

Step 4: Enjoy Live Podcasts!

Source 1:
Source 2:

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How-To Set-Up your own Miataru server

Since a user of miataru asked about how to set-up your own miataru server I’ve decided to make a short screen recording of how you can do it with the help of Nitrous.IO:


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When your VU+ DUO just shows a red light and does not start up

So it happened to one of the VU+ Duos in the house. After a clean shutdown it did not boot up as expected but instead just showed the red light. It still blinked on remote keypresses and the harddisk spun up. Nothing else happened with it.

So it was bricked.

Reading the forums about that pointed to a capacitor on the board that quite regularly seems to fail. C807 is it’s name and it’s located near the Harddisk and the power-supply part of the VU+ Duo.

When I looked at the capacitor it did not seem to be faulty or anything. So without the right tools to measure I’ve decided to just give it a shot and replace the original 16V 220uF 85 degrees celsius capacitor with a 105 degrees celsius 16V 330uF one.

In my case I’ve taken out the board, to have a little bit of extra space, and cut of the old capacitor. Desoldering would be nicer looking but, well …

Replacing it on the left-over pins of the old capacitor was a matter of seconds.

After putting the board back in, the VU+ Duo powered up and booted as new. Brilliant!

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Debugging Linux: Latency heatmaps

“Odd patterns of I/O latency can be hidden by line graphs and summary statistics, and revealed by histograms and heat maps. In my previous post I showed my Linux iosnoop tool, which can trace block device I/O along with timestamps and latency. This information can be visualized, revealing any odd patterns.”

Bildschirmfoto 2014-07-27 um 12.55.50


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Do you need an alternative shell for your terminal?

“Commands have been a big part of computing ever since the 1970’s.  Their power comes from their simplicity.  Just type a word or two to do what you want.  The time has come to bring this power together with the usability and convenience of modern interfaces.”

“Xiki is open and flexible.  It’s open source, and brings together tools, languages, shells, and text editors, rather than competing with them.  Open formats and languages are the best thing for the tech ecosystem.  HTML and JSON made the web what it is today.  And the web arguably made everything else. 

Xiki strives to be the simplest possible way (and ways) to create interactive interfaces.  This means a text in and text out interface.  Since everything is text, almost nothing is against the rules when you’re creating an interface in Xiki.  Xiki stands for “expanding wiki”, and is inspired by the wiki philosophy of fully editable text, with simple syntaxes (like “>” for a heading, and “-” for a bullet).  Xiki extends wiki ideas to user interface in general.”


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Next step: Holodeck.

“The Infinadeck is the world’s first affordable omnidirectional treadmill that is designed to work both in augmented and virtual reality.  This revolutionary device provides the missing link making it now possible to have a true Holodeck experience. You might say, “Reality just got bigger”.”


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Nitrous – full IDE in your browser – with Collaboration!

“Nitrous is a backend development platform which helps software developers save time by cutting out the repetitive parts of creating development environments and automating them.

Once you create your first development environment, there are many features which will make development easier.”

Bildschirmfoto 2014-07-06 um 11.38.49

So what you’re getting is:

  • a virtual machine operated for you and set-up with a single click
  • A full-featured IDE in your browser
  • Code-Collaboration by inviting others to edit your project
  • a debugging environment in which you can test-run and work with your code

Here are some screenshots to get you a feel for it:


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Scaling Linux: Perfomance Tools and Measurements


If you ever experienced a missmatch between the performance you expected from a server or application running on Linux you probably started to debug your way into it why the applications performance is not on the expected levels.

With Linux being very mature you get an enormous amounts of helpers and interfaces to debug the performance aspects of the operating system and the applications.

Want to see proof? Here – a map of almost all the thingies and interfaces you got:linuxperftools

Thankfully Brendan Gregg put together a page with videos and further links to drill into those interfaces and methods above.


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How to get a list of all recent Podcasts on SONOS

I am using an external podcast download tool to stay updated on all podcasts I subscribed to. For this purpose SubSonic is a good choice – actually for a lot more also.

Screen Shot 2014-07-02 at 18.56.52

One of the quirks of the SONOS products is that Podcasts are not really well supported. In fact there is no support at all.

So I wrote a tool that extends the SONOS players with the functionality to “remember” play positions within audiobooks and podcasts. Now what’s left to properly have podcasts supported is a view of the most recently updated podcasts. Wouldn’t it be nice to have a “Folder View” in the SONOS controller of what’s new across all the different podcasts you are subscribed to?

Now here’s the trick:

Use a small script on any RaspberryPi in the house to dynamically create hardlinks to the podcasts files in a “Recently Updated Podcasts” folder.

The script is something like this:

find /where-your-podcasts-are/ -type f -printf ‘%TY-%Tm-%Td %TT %p\n’ | sort | tail -n 25 | cut -c 32- | sed -e “s/^/ln \”/” -e “s/$/\”/” -e “s/$/ \”\/recentPodcasts\/\”/” | sh

This short line will go through all folders and subfolders in /where-your-podcasts-are/ and then create Hardlinks in /recentPodcasts to the most recent 25 files.

That way, and when /recentPodcasts/ is made accessible to your SONOS controllers, you’ll have something like this:

Screen Shot 2014-07-02 at 19.17.24

Source 1:
Source 2: play position bookmarker

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Boblight Alternative: Hyperion

After setting up Boblight on two TVs in the house – one with 50 and one with 100 LEDs – I’ve used it for the last 5 months on a daily basis almost.

First of all now every screen that does not come with “added color-context” on the wall seems off. It feels like something is missing. Second of all it has made watching movies in a dark room much more enjoyable.

The only concerning factor of the past months was that the RaspberryPi does not come with a lot of computational horse-power and thus it has been operating at it’s limits all the time. With 95-99% CPU usage there’s not a lot of headroom for unexpected bitrate spikes and what-have-you.

So from time to time the Pis where struggling. With 10% CPU usage for the 50 LEDs and 19% CPU usage for the 100 LEDs set-up there was just not enough CPU power for some movies or TV streams in Full-HD.


So since even overclocking only slightly improved the problem of Boblight using up the precious CPU cycles for a fancy light-show I started looking around for alternatives.

“Hyperion is an opensource ‘AmbiLight’ implementation controlled using the RaspBerry Pi running Raspbmc. The main features of Hyperion are:

  • Low CPU load. For a led string of 50 leds the CPU usage will typically be below 1.5% on a non-overclocked Pi.
  • Json interface which allows easy integration into scripts.
  • A command line utility allows easy testing and configuration of the color transforms (Transformation settings are not preserved over a restart at the moment…).
  • Priority channels are not coupled to a specific led data provider which means that a provider can post led data and leave without the need to maintain a connection to Hyperion. This is ideal for a remote application (like our Android app).
  • HyperCon. A tool which helps generate a Hyperion configuration file.
  • XBMC-checker which checks the playing status of XBMC and decides whether or not to capture the screen.
  • Black border detector.
  • A scriptable effect engine.
  • Generic software architecture to support new devices and new algorithms easily.

More information can be found on the wiki or the Hyperion topic on the Raspbmc forum.”

Especially the Low CPU load did raise interest in my side.

Setting Hyperion up is easy if you just follow the very straight-forward Installation Guide. On Raspbmc the set-up took me 2 minutes at most.

If you got everything set-up on the Pi you need to generate a configuration file. It’s a nice JSON formatted config file that you do not need to create on your own – Hyperion has a nice configuration tool. Hypercon:

Screen Shot 2014-06-28 at 08.52.51

So after 2 more minutes the whole thing was set-up and running. Another 15 minutes of tweaking here and there and Hyperion replaced Boblight entirely.

What have I found so far?

  1. Hyperions network interfaces are much more controllable than those from Boblight. You can use remote clients like on iPhone / Android to set colors and/or patterns.
  2. It’s got effects for screen-saving / mood-lighting!
  3. It really just uses a lot less CPU resources. Instead of 19% CPU usage for 100 LEDs it’s down to 3-4%. That’s what I call a major improvement
  4. The processing filters that you can add really add value. Smoothing everything so that you do not get bright flashed when content flashes on-screen is easy to do and really helps with the experience.

All in all Hyperion is a recommended replacement for boblight. I would not want to switch back.

Source 1: Setting up Boblight
Source 2:

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APN Changer for iOS – when you’re abroad and in need of different mobile provider settings

When traveling you might find yourself in the situation that you get a new SIM card into your iPhone and it’ll start and do it’s automatic magic for you. And eventually you well end up with the right provider settings by default.

But there are some cases when it picks the wrong provider settings. Like in my case. It picked NTT docomo in Japan with the default NTT docomo settings. In my case I was using a reseller for NTT (as described here) and that demanded different provider settings to work.

Unfortunately in all it’s wisdom the iPhone did not allow me to set the carrier settings. It just displayed the “Automatic” choice. So I went to the APN Changer website, entered the settings and installed a custom provider setting to my device. This works without any Jailbreak with iPhones without SIM Lock.


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using the RaspberryPi to make all SONOS speakers support Apple Airplay

Airplay allows you to conveniently play music and videos over the air from your iOS or Mac OS X devices on remote speakers.

Since we just recently “migrated” almost all audio equipment in the house to SONOS multi-room audio we were missing a bit the convenience of just pushing a button on the iPad or iPhones to stream audio from those devices inside the household.

To retrofit the Airplay functionality there are two options I know of:

1: Get Airplay compatible hardware and connect it to a SONOS Input.

airportexpress_2012_back-285111You have to get Airplay hardware (like the Airport Express/Extreme,…) and attach it physically to one of the inputs of your SONOS Set-Up.  Typically you will need a SONOS Play:5 which has an analog input jack.


2: Set-Up a RaspberryPi with NodeJS + AirSonos as a software-only solution

You will need a stock RaspberryPi online in your home network. Of course this can run on virtually any other device or hardware that can run NodeJS. For the Pi setting it up is a fairly straight-forward process:

You start with a vanilla Raspbian Image. Update everything with:

sudo apt-get update

sudo apt-get upgrade

Then install NodeJS according to this short tutorial. To set-up the AirSonos software you will need to install additional avahi software. Especially this was needed for my install:

sudo apt-get install git-all libavahi-compat-libdnssd-dev

You then need to get the AirSonos software:

sudo npm install airsonos -g

After some minutes of wait time and hard work by the Pi you will be able to start AirSonos.

sudo airsonos

And it’ll come up with an enumeration of all active rooms.

Screen Shot 2014-06-25 at 11.38.47

And on all your devices it’ll show up like this:



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How to use the Tokyo public transportation system as a visitor

Being in Tokyo as a visitor brings a lot of challenges. Since you gotta use the public transport offers to get from A to B. Now we had the same challenge this May and this is how we tried to solve it.

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Problem: How do you know which train lines you take and where they are?

Solution: Use Google Maps (you need mobile internet access!) to find your route

The public transportation feature of Google Maps works like a charm. It’s accurate as it can be and offers even walking instructions to get to the right platform or train station.

Notice the colored lines next to the different stations. That’s the color you’re looking for on the train. They are color coded! To find your right platform just take the information that Google gives you and look out for it. It will be written on signs “Rinkai towards Tokyo Teleport”.


Problem: Okay I know which train I have to use. But before I enter the platform I have to pass the ticket gate. How do I buy a ticket? How do I know which one?

Solution: Get a Suica card and charge it! If you’re a group travelling: Look out for cheap group ticket offerings.

A Suica card (aka “Super Urban Intelligent Card”) can be used instead of buying a ticket. You can buy it where you can buy the tickets – most of the time it’s 500 Yen + charge. Charging it with some Yen is crucical since the gates will not let you in when your card is not at least charged with 210 Yen.

You may ask: If I buy a ticket from A to B I have to pay the price upfront. When I use the Suica how does it work then? Easy answer: When you enter the train station through the ticket gate you pass it with your Suica card. It will start a journey for you. When you exit it will end the journey. The card and system is intelligent enough to calculate all steps in between, add them up and substract the fare price from your Suica balance. It always takes the cheapest price for single travellers.

If you’re on your way as a group you might want to use the ticket machines before going through the ticket gates. The Suica is a personal card and only suited for one person to be used. So you cannot pass it through the ticket gate back and enter the ticket gate again without causing panic with the service personell.

To buy tickets for groups I suggest to switch the terminals to english – most of them will offer that option. You then have to specifically know where you want to go. Sometimes it’s the easiest way to just go to the counter and buy them there.

Sometimes when you bought tickets you find out that you made a mistake. Fear not! You can give them back and by doing so get your money back. Service personell is awesome and will help you at any time! DO NOT PANIC!

Another awesome feature you get ‘for free’ by having a Suica card is that you can use it with all the vending machines available everywhere in the train stations. Just pick the beverage you want and swipe the card. Done!

Beware: fill the card up before going out of the ticket gate when you used it all up!

If you happen to have a NFC enabled device (like most Android phones) you can install the Suica Reader app from the Google Store and get information about what happened to your card so far.

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how to get mobile Internet (3G / LTE) in Japan

If you visit Japan the next time and you want to get perfectly good Internet access while there on your mobile phone I can recommend the b-mobile offer. On my last stay in Japan (May 2014) I tried their service for the first time and I was not let down.

They give you two options: The 1 GB prepaid option gives you 1 GB as fast as possible. The 14days prepaid gives you 14 days of limited speed coverage (300kbps).

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I went for the 14 days prepaid option knowing that I might get some usage depending on where I go. The 300kbps where faster than I thought – at no given time I experienced any speed problems. The coverage was awesome since it just dialed into NTT Docoms 3G/LTE network.

For just under € 30 this is an awesome option for any traveller. Even better: You can pick it up at the Airport or you can have it delivered to your hotel! We tried both and it worked both as expected. Fast delivery, perfect service!


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Need to do Load Tests? Try Tsung!

Tsung is an open-source multi-protocol distributed load testing tool

It can be used to stress HTTP, WebDAV, SOAP, PostgreSQL, MySQL, LDAP and Jabber/XMPP servers. Tsung is a free software released under the GPLv2 license.

The purpose of Tsung is to simulate users in order to test the scalability and performance of IP based client/server applications. You can use it to do load and stress testing of your servers. Many protocols have been implemented and tested, and it can be easily extended.

It can be distributed on several client machines and is able to simulate hundreds of thousands of virtual users concurrently (or even millions if you have enough hardware …).

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did you know that the marriage rate in Ohio correlates with legal executions? Spurious Correlations!

I took notice of a website called “Spurious Correlations“. It seems that it collects all sorts of correlating statistics to proof the point of how important context is to statistics. Enjoy!

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new Webcams of Bamberg – even a panoramic one!

We’re living near a very nice city called Bamberg. And after a long time there are new Webcams availabel for anyone to look at. Even a 360 degree panoramic view!

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MOSH (Mobile Shell) – fixing SSH for everyone

How many times did you experience a connection loss on your terminal window in the last week? Yeah I know – like everytime you close the lid of your notebook and move to a different place. So like a dozen times every day.

And everytime you reconnect to your servers and you use things like screen to keep your terminals open and your programs running while you’re disconnected.

On the other hand – did you ever curse the internet gods while you tried to do a very important check or bugfix to a machine whilst on a train or mobile roaming network? It’s not what I would call fun-times. When there are no constant disconnects the lag is just infuriating. MOSH also solves this since it’s predicting and responding way faster then vanilla SSH. Your terminal becomes useable again!

So there’s now MOSH to the rescue:

Remote terminal application that allows roaming, supports intermittent connectivity, and provides intelligent local echo and line editing of user keystrokes.
Mosh is a replacement for SSH. It’s more robust and responsive, especially over Wi-Fi, cellular, and long-distance links.
Mosh is free software, available for GNU/Linux, FreeBSD, Solaris, Mac OS X, and Android.

Install it on your servers and your clients and never lose a connection again.

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TIME_WAIT – how does it work?

The Problem Addressed by the TIME-WAIT State

The Problem Addressed by the TIME-WAIT State

The purpose of TIME-WAIT is to prevent delayed packets from one connection being accepted by a later connection. Concurrent connections are isolated by other mechanisms, primarily by addresses, ports, and sequence numbers


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when javascript equality checks, always use ===

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IPv6 native root server has problems with OpenFire Jabber / XMPP Server to Server

I was setting up a new root-server machine and went for the Debian 7 minimal set-up. Thankfully the root-server provider I am using (hetzner) is connected with IPv4 and IPv6 natively. Awesome stuff!

If you’re using an IPv6 native set-up these days you STILL have to be cautious about possible side-effects with software having bugs and not knowing how to deal with these ginormous ip adresses.

So there’s a well known Jabber / XMPP server that I am using for some years now without any issues. I was even using it on native IPv6 connected machines earlier.

But with the fresh and clean set-up of Debian 7 and IPv6 by the hoster several problems started bubbling up.

1: the ‘there can only be one ipv*’ problem

Turns out that the debian team decided to set a system setting by default that lets IPv6 aware applications bind to IPv6 only. Good thing, you can disable it by adding this to your sysctl.conf:


2: the ‘who resolves first is right’ problem

When you get a IPv6 native machine it might have a resolv.conf consisting of IPv4 and IPv6 name servers. And don’t worry: Everything is going to be all-right as long as the software you’re planning to use is perfectly capably dealing with the answers of both types of servers. The IPv4 ones will default to the A records, the IPv6 ones to the AAAA record.

Now there’s OpenFire. A stable and easy to use XMPP / Jabber server implementation. It’s based upon Java and I am running it with Java 7 on my Debian machine.

Unfortunately in the current 3.9.1 version of OpenFire there’s a bug that leads to Server-to-Server XMPP connections not working when they resolv to IPv6. So for example your Google-Talk contacts won’t work at all.

The bug itself is rather stupid: Seems that OpenFire expects an IPv4 adress from the DNS lookup and crashes on an IPv6 adress.

The solution is as easy as the bug is stupid: Remove the IPv6 defaulting nameservers from your resolv.conf.

# nameserver config
#nameserver 2axx:yyy:0:zzzz::add:9898
#nameserver 2axx:yyy:0:zzzz::add:9999
#nameserver 2axx:yyy:0:zzzz::add:1010

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Brackets: a multi-platform editor written in javascript – including NodeJS

“Brackets is an open source code editor for web designers and front-end developers.”


On the first tries it’s an awesome thing to have all that JavaScript debugging, Live HTML editing and what-not in one place. Give it a spin.

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weave your net of things that have internet…ehm – internet of things


The internet of things” is a buzzword used more and more. It means that things around you are connected to the (inter)network and therefore can talk to each other and, when combined, offer fantastic new opportunities.

Yeah right.

So NodeRed is a NodeJS based toolset that allows you to create so called “flows” (see picture above). Those flows determine what reacts and happens when things happen. Fantastic, told you!

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How to fix a mono CS0589 Internal compiler error during parsingSystem.FormatException error on the RaspberryPi

When you want to compile some C# code using MONO on Linux on your RaspberryPi and you encounter this strange error message:

error CS0589: Internal compiler error during parsingSystem.FormatException

You need to do:

  1. Update your Debian by running:

    sudo apt-get upgrade
    sudo apt-get update

  2. Upgrade your RaspberryPi firmware:

    sudo rpi-update

  3. Reboot your RaspberryPi
  4. Retry compiling – should work now.

The reason for Mono to crap out like above: Previous Mono versions and RaspberryPi firmwares where not compatible due to one side using HardFP and the other not.

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ZFS Tutorial

“ZFS is really the final word in filesystems. With a feature set longer than this tutorial, it can take a while to master. You can set many more options per dataset, enable disk usage quotes and much more. Once you’ve used it and seen the benefits, you’ll probably never want to use anything else. Hopefully this has been helpful to get you on your way to becoming a FreeBSD ZFS master.”


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I give you: the SONOS Audiobook / Podcast Auto Bookmarker – never lose your Listening Progress again…

Since the SONOS system I’ve bought turned out to be highly hackable I’ve spent some quality-time this weekend fixing the worst downside I’ve found so far that the SONOS system had for me

I am listening to a lot of Podcasts and Audiobooks. And it turns out that those two Genre are not particularly good supported by SONOS. When you’re listening to a 4 hour podcast and you stop it to play a song in between (since you stretch the listening of that podcast to several days) the next time you start that 4 hour podcast the SONOS system did not remember the position that you stopped at the last time and restarts the podcast from the beginning.

If you did not remember where you left of the last time, you’re lost. The same goes for Audiobooks.

Now this is the first feature I am teaching my SONOS system. And I am opensourcing it so you can do it as well.

SONOS Auto Bookmark Tool

Everything you need can be run on a RaspberryPi:

  1. You need NodeJS and node-sonos-http-api installed and running.
  2. You need MONO and sonos-auto-bookmarker (change the configuration.json file in bin/Debug after you xbuilded the .sln file)

Now the Auto Bookmarker Tool will, with the help of the sonos-http-api, monitor your household and whenever something longer than 10 minutes is played and stopped it bookmarks the last played position. Whenever you restart that track it will then seek to the last known position automatically.

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Let the SONOS hacking begin!

I always wanted a networked multi-room audio solution as you can easily see here and here and here and here. Now it seems I’ve finally found something that integrates very well into our music listening habits and our infrastructure. And on top of that it turned out to be highly hackable.

I’ve went with SONOS for that multi-room solution. After trying two speakers for two rooms I’ve invested the budget into the full-house solution (not all speakers on below picture). And finally everything is as I always wanted.

Be warned: If you buy one speaker, you will definitly buy more.


So what’s in those boxes? Besides beautiful and high-quality speakers there’s a 250 Mhz linux powered computer inside each speaker. It got 64Mbytes of memory and wireless adapters to span it’s own wireless mesh network (hidden by default).

Each speaker on it’s own can be controlled and accessed through the SONOS controller applications (Windows/Mac/iOS/Android) or through several tools that open up new possibilities.

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There will be more articles coming on the topic of hacking SONOS, adding functionality and using it for things not officially planned for by the manufacturer. Joy!


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How to install NodeJS and NPM on the RaspberryPi without getting “Illegal Instruction” error messages

I tried a couple of times to compile NodeJS on the RaspberryPi and failed miserably. It not only takes ages to compile NodeJS on the Pi. After the successful compile and install run most of the time running it just results in an error message “Illegal Instruction” or “Ungültiger Maschinencode”.

Now there’s a pretty easy way to do that on your own. Run these commands:


After the download is finished successfully you can install it by running this as root:

sudo dpkg -i node_latest_armhf.deb

This will have installed a relatively new NodeJS built as well as NPM on your RaspberryPi. Don’t panic when NPM is slower than you would expect… just be patient.


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On-Screen OCR – helps you when all you get is an image…

“You want to extract one paragraph of text from a pdf your coworker sent you? One quote from your professor’s presentation? A couple of code lines from this tutorial clip on your favourite movie platform? It’s just one hotkeypress away. OCR everything on the fly.

Condense is the product of many frustating years of using overly complicated OCR software. “Take a screenshot, boot up your OCR suite, select the area you want to extract, select an output file…” Oftentimes typing out is faster than walking through this procedure.”

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document your REST interfaces with style: Swagger

Swagger is a specification and complete framework implementation for describing, producing, consuming, and visualizing RESTful web services. The overarching goal of Swagger is to enable client and documentation systems to update at the same pace as the server. The documentation of methods, parameters, and models are tightly integrated into the server code, allowing APIs to always stay in sync. With Swagger, deploying managing, and using powerful APIs has never been easier.”

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miataru can embed your location into any website now!

An exciting new feature has been added to the Miataru service! It’s now possible to embed the location of a device into any website. Here’s an example:

It’s a pretty easy process. When your device is available on the standard public miataru service you only have to embed an iFrame into the website. Just like this:

<iframe width=”320″ scrolling=”no” height=”240″ frameborder=”0″ src=”;Demo Device”></iframe>

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GraphHopper: blazingly fast routes with OpenStreetMap

Playing with OpenStreetMap resources lately I came to the point where I wanted to calculate routes between points based on the OSM data. Now there is GraphHopper to the rescue! It’s opensource and awesome!

“GraphHopper offers memory efficient algorithms in Java for routing on graphs. E.g. Dijkstra and A* but also optimized road routing algorithms like Contraction Hierarchies. It stands under the Apache License and is build on a large test suite.”

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setting up boblight with a Raspberry Pi and RaspBMC

Some might know AmbiLight – a great invention by Philips that projects colored light around a TV screen based upon the contents shown. It’s a great addition to a TV but naturally only available with Philips TV sets.

Not anymore. There are several open-source projects that allow you to build your very own AmbiLight clone. I’ve built one using a 50-LEDs WS2801 stripe, a 5V/10A power supply, a RaspberryPi, and the BobLight integration in RaspBMC (this is a nice XBMC distribution for the Pi).

Boblight is a collection of tools for driving lights connected to an external controller.

Its main purpose is to create light effects from an external input, such as a video stream (desktop capture, video player, tv card), an audio stream (jack, alsa), or user input (lirc, http). Boblight uses a client/server model, where clients are responsible for translating an external input to light data, and boblightd is responsible for translating the light data into commands for external light controllers.”

The hardware to start with looks like this:


I’ve fitted some heat-sinks to the Pi since the additional load of controlling 50 LEDs will add a little bit of additional CPU usage which is desperately needed when playing Full HD High-Bitrate content.

The puzzle pieces need to be put together as described by the very good AdaFruit diagram:

diagramAs you can see the Pi is powered directly through the GPIO pins. You’re not going to use the MicroUSB or the USB ports to power the Pi. It’s important that you keep the cables between the Pi and the LEDs as short as possible. When I added longer / unshielded cables everything went flickering. You do not want that – so short cables it is 🙂


When you look at aboves picture closely you will find a CO and DO on the PCB of the LED. on the other side of the PCB there’s a CI and DI. Guess what: That means Clock IN and Clock OUT and Data IN and Data OUT. Don’t be mistaken by the adapter cables the LED stripes comes with. My Output socket looked damn close to something I thought was an Input socket. If nothing seems to work on the first trials – you’re holding it wrong! Don’t let the adapters fitted by the manufacturer mislead you.

Depending on the manufacturer of your particular LED stripe there are layouts different from the above image possible. Since RaspBMC is bundled with Boblight already you want to use something that is compatible with Boblight. Something that allows Boblight to control each LED in color and brightness separately.

I opted for WS2801 equipped LEDs. This pretty much means that each LED sits on it’s own WS2801 chip and that chip takes commands for color and brightness. There are other options as well – I hear that LDP8806 chips also work with Boblight.

My power supply got a little big to beefy – 10 Amps is plenty. I originally planned to have 100 LEDs on that single TV. Each LED at full white brightness would consume 60mA  – which brings us to 6Amps for a 100 – add to that the 2 Amps for the PI and you’re at 8A. So 10A was the choice.

To connect to the Pi GPIO Pins I used simple jumper wires. After a little bit of boblightd compilation on a vanilla Raspbian SD card (how-to here). Please note that with current RaspBMC versions you do not need to compile Boblight yourself – I’ve just taken for debugging purposes as clean Raspbian Image and compiled it myself to do some boblight-constant tests. Boblight-constant is a tool that comes with Boblight which allows you to set all LEDs to one color.

If everything is right, it should look like this:

working_first_timeNow everything depends on how your LED stripes look like and how your TVs backside looks like. I wanted to fit my setup to a 42″ Samsung TV. This one already is fitted with a Ultra-Slim Wall mount which makes it pretty much sitting flat on the wall like a picture. I wanted the LEDs to sit right on the TVs back and I figured that cable channels when cut would do the job pretty nicely.

To get RaspBMC working with your setup the only things you need to do are:

  1. Enable Boblight support in the Applications / RaspBMC tool
  2. Login to your RaspBMC Pi through SSH with the user pi password raspberry and copy your boblight.conf file to /etc/boblight.conf.

The configuration file can be obtained from the various tutorials that deal with the boblight configuration. You can choose the hard way to create a configuration or a rather easy one by using the boblight configuration tool.

I’ve used the tool 🙂

Boblight Config ToolNow if everything went right you don’t have flickering, the TV is on the wall and you can watch movies and what-not with beautiful light effects around your TV screen. If you need to test your set-up to tweak it a bit more, go with this or this.


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Source 6: How-To-Compile-Boblight
Source 7: Boblight Config Generator
Source 8: Boblight Windows Config Creation Tool
Source 9: Test-Video 1
Source 10: Test-Video 2

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“Compressing” JSON to JSON



The internet and all those browsers and javascript applications brought data structures that are pretty straight-forward. One of them is JSON.

The wikipedia tells about JSON:

“JSON (/ˈdʒeɪsɒn/ JAY-soun, /ˈdʒeɪsən/ JAY-son), or JavaScript Object Notation, is an open standard format that uses human-readable text to transmit data objects consisting of attribute–value pairs. It is used primarily to transmit data between a server and web application, as an alternative to XML.”

Unfortunately complex JSON can get a bit heavy on the structure itself with over and over repetitions of data-schemes and ids.

There’s RJSON to the rescue on this. It’s backwards compatible and makes your JSON more compressible:

“RJSON converts any JSON data collection into more compact recursive form. Compressed data is still JSON and can be parsed with JSON.parse. RJSON can compress not only homogeneous collections, but also any data sets with free structure.

RJSON is single-pass stream compressor, it extracts data schemes from document, assign each schema unique number and use this number instead of repeating same property names again and again.”

Of course this is all open-source and you can get your hands dirty here.

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Xcode Cheat Sheet

While I am using Xcode a lot lately I quickly got used to one or two keyboard shortcuts that come in handy once every while. This cheat sheet aims at bringing you a lot of shortcuts that are pretty hard to remember if you’re not using them all the time (at least for me).


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the Miataru Browser Client Application is here!

After getting the server and the iOS client application to the people I’ve sat down and started doing something I have not done yet – writing a web application with no server side except a standard HTTP server.

Here’s a little demonstration which I will explain in more detail below:

The default Miataru service can be accessed through the client application with this URL: – This will open a new browser window with a completely fresh session of the application. Since Miataru is all about control of your own data this webapplication does not store anything on any servers – every access to the internet is read-only and only to the Miataru service (just “GetLocation”). Oh – and by default it uses SSL to encrypt all traffic from and to the Miataru service.

You can start by entering DeviceIDs you know or you can – for test purposes – use a DeviceID I am providing for test purposes: BF0160F5-4138-402C-A5F0-DEB1AA1F4216

Of course, the easiest way is to just embedd the DeviceID into the URL, just like this:

Oh and if you want to see the device moving on your iPhone just use the miataru iOS client and scan this QR code here:


So that was easy – but if the application does not store anything on any server, how does it maintain the Known Devices list between browser sessions (open/closes of the browser) you ask? – It’s using HTML5 WebStorage to store these information locally in your browser. This has the advantage of being completely local, but also the disadvantage that it is not shared between browsers or machines.

Like usual this whole application is also available completely free of charge and open-sourced to be used, edited and installed on-premise if you like.

Let me know how you like it!

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the dark side of user interface design



“A Dark Pattern is a type of user interface that appears to have been carefully crafted to trick users into doing things, such as buying insurance with their purchase or signing up for recurring bills.”

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