studying my hobby


AVR, Raspberry Pi, VW Beta: VAG CDC Faker

(4 votes, average: 5.00 out of 5)

I was tired connecting my cellphone with an old cassette adapter to my VW Golf with an Beta 5 in it. I needed something new, something cool. And here it is, a fully functional interface between the Beta 5 and any device you want to play the music with.

This project raised out of an ebay search: I just wanted to know if there is a solution to get an AUX input on the car radio. Yes there is, even complete mp3 players are available. But that's not what I wanted - at first!

Then I started digging the web for more info about the protocol the radio talks to cd changers.
The idea was to build a tiny thingy that fakes a cd changer and simply enables the AUX input (as it is available in several online stores). But during the development my ambition became greater and I wanted to read the keys pressed on the radio to remote control my RPi.

1. Understanding the Protocol

First of all this is the pinout of the radio:
The interesting cell is no. 3, the blue one.
DATA IN simply is MOSI of an 8bit SPI interface with special timings between the bytes
CLOCK is SCK of the SPI
DATA OUT is the key code of the pressed key on the radio itself

The radio needs a sequence of bytes to enable the AUX input and display CD# and TR#. It looks likes this:

frame cd#   tr#   time  time  mode  frame frame
0x34, 0xBE, 0xFF, 0xFF, 0xFF, 0xFF, 0xCF, 0x3C

cd# and tr# are sent inverted. So this sequence will display: CD1 TR00
mode sets the playmode (PLAY|SHFFL|SCAN)


Raspberry Pi: Setup Debian with SanDisk Extreme

(2 votes, average: 3.50 out of 5)

Finally my RPi has been delivered! After unboxing it I really couldn't image that is was that tiny. First thing I did, was grabbing my 8GB SanDisk SD-Card and copying the rootfs debian6-19-04-2012 onto it.

After plugging the sd card in the RPi and connecting power supply the problems came up...

This article is not a detailed guide how to set up your RPi. It just describes my second afford to get the RPi booting flawlessly in a few words I can refer to in the future.

Problems I had

  • device didn't boot at all
  • no serial output on the GPIOs
  • login failures with definitely correct password
  • mouse/keyboard stopped working after startx
Filed under: Hardware, Raspberry Pi | 11,132 views Continue reading

Remote printing: Debian and Google Cloud Print

(8 votes, average: 4.75 out of 5)

Have you ever heard of google cloud print? It allows you to add your printers to the cloud and share them. You can print on them from any device supporting this service, even if you are on another network. This sounds pretty cool, I gave it a try and I am really amazed.

None of my printers doesn't support cloud print directly, so I need a google chrome installation to share the printer. But I don't want to have my computer to run when printing remotely. There is a project called Google CloudPrint on Linux which allows you to use this nice service from the command line. At this point the dockstar or the linkstation joines the game.


Shairport: Debian as Airtunes Server

(2 votes, average: 5.00 out of 5)

Recently some friends and me were talking about streaming music from iTunes to my dockstar with an usb sound device connected.
I knew there is a solution, so I started some research an found shairport at The project looks quite interesting and I tried to set everything up that I am able to play my music remotely.

First there are some dependencies you need to install:

Now all you need to do is download the sources, make and install them:
Get the sources at


miniDLNA: Dockstar as DLNA-Server v1.1.4

(20 votes, average: 4.80 out of 5)

Today I noticed there is a new version of miniDLNA available. When the build process was running I decided to make a deb-file that you guys don't have to compile the sources yourself.

Some people don't want to install the build-environment or sources of dependencies, that's two of the reasons why I put the files together into an installable deb-file, there you go: (Look at the updates below for feature versions!)

Now edit the config in /etc/minidlna.conf and start the service:

If everything works fine, the server should show up on your dlna-clients.

If your kernel supports inotify (my 3.1.10 does) and you want miniDLNA to use it, check if the device is present:

If it's not created automatically by udev, you have to do it manually:

After you restarted miniDLNA you should instantly see directorychanges on your clients.

Update 12.09.2011: v1.0.22

I just compiled the new version and packed it to a new deb file. To update just install it:

In the version tag I added a version number lower than sid to avoid problems during system upgrade, thanks to fear_factory84!

Update 28.01.2012: v1.0.23

Today I found some time to build the new version into a deb-file. There you go:

Update 21.02.2012: v1.0.24

Just build the new version into a deb-file. There you go:

Update 24.07.2012: v1.0.25

Just build the new version into a deb-file. There you go:

Update 18.06.2013: v1.0.26

Just build the new version into a deb-file.
Because of a dependency change, you need to update libavformat. It isn't part of the debian repo, so we need deb-multimedia. Follow the intructions on how to include it in your sources.list!
Then install my .deb and update the deps:

Update 09.03.2014: v1.1.2

Just build the new version into a deb-file.
Maybe you need to remove older versions of minidlna, because the developer changed its path from /usr/sbin to /usr/local/sbin.
Backup your current config and install my .deb:

Update 06.09.2014: v1.1.4

Just build the new version into a deb-file.
Backup your current config and install my .deb:

Filed under: Dockstar, Goflex, Hardware, Linkstation, Linux, Raspberry Pi | 125,123 views 114 Comments

Debian as Printserver and Scanserver with HPLIP, CUPS, SANE

(10 votes, average: 4.80 out of 5)

It's nice to have a little home-server like the Seagate Dockstar or the Buffalo Linkstation running debian quite smoothly. What do you do if you would like to use your printer and scanner with more than one device?

Yes, you connect it to your server and share it over the network!
Because I had to set this up in two locations for now I decided to write down those steps I took from powering on the printer through printing the first testpage I can scan later on.

This HowTo requires debian squeeze installed on your Dockstar/Linkstation. If you haven't done this yet, please refer to other articles in this blog.


Dockstar: HowTo setup OpenVPN on Debian

(8 votes, average: 5.00 out of 5)

Well, if you want to have a secure connection to your dockstar or even your home net, this post describes all steps you have to take to get this done. In my setup I have a dd-wrt router connected to the internet and forwarding all needed ports to the dockstar. You probably don't use a firewall on the debian machine, but you will have to, because we need package forwarding to reach the home net through the VPN tunnel. I assume you don't use your dockstar as the default gateway for your LAN, so you will need an additional route in the router:

Let me explain the path of the packages of a ping from a remote machine to a host in the LAN. For the different subnets refer to the exhibit (VPN:; LAN:


Debian as Download-Station: pyLoad (v0.4.7+)

(9 votes, average: 4.78 out of 5)

You want to turn your little home-server into a download agent you can control through a web-interface or a jabber account on your mobile phone? Then follow these few steps to get this done quickly.
What is pyLoad? Let's read the introduction from the developers' website:

pyLoad is a fast, lightweight and full featured download manager for many One-Click-Hoster, container formats like DLC, video sites or just plain http/ftp links. It aims for low hardware requirements and platform independence to be runnable on all kind of systems (desktop pc, netbook, NAS, router).
Despite its strict restriction it is packed full of features just like webinterface, captcha recognition, unrar and much more. []

Tagged as: , , , , | 41,539 views Continue reading

Dockstar-NAS: Automount, hd-idle, Samba, FTP

(4 votes, average: 5.00 out of 5)

Having debian installed on the dockstar is quite nice but how about access to the data in there? In this article I will explain how you easily set up a data-storage with autofs, hd-idle, samba and proftpd.
I assume you have debian squeeze running on a usb stick and your data you want to share on your network is stored on an external hard-drive.