Ubuntu/Debian Installer: Overriding preseed values using boot kernel parameters

When using a pressed file there’s a vicious circle if you also want to pass boot parameters: Because you pass the preseed path using boot parameters (e.g. url=http://path/to/preseed.cfg) the installer has to interpret the boot parameters first and can then read/use those vales found in the loaded preseed file.

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Equip an old IDE computer with a big HDD

One of my computers I run is an old IBM which has no SATA connectors. At least there are three possibilities to add an uptodate HDD with sufficient space:

  • Buy an IDE HDD: Nowdays there a few IDE HDDs available and they are much more expensive than their SATA mates
  • Buy an SATA-PCI controller: Perhaps this is the best option but I did not have any free PCI slot
  • Buy an SATA-IDE-adapter This is what I did: Of course throughput is limited to the IDE interface ad not to the PCI bus like the possibility above. Since this does not matter in my case I decided to use this solution. The adapter is just 1,50€ when purchasing in china, e.g. at ebay. Because the BIOS was not able to work with an IDE of that size properly I had to create a separate boot partition otherwise grub failed with “Attempt to access block outside partition

 

 

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Tracking aircrafts using a software defined radio

While reading Raspberry Pi in the sky: How to build this awesome $115 airplane tracker my <10$ SDR (software defined radio) came to my mind. It’s a RTL2832U based DVB-T USB stick I did purchase a year ago.

So after a minute of searching the net I found dump1090 which works out of the box and has also a builtin webserver for showing the data using google maps. However here is an example output using the interactive mode.

Hex    Flight   Altitude  Speed   Lat       Lon       Track  Messages Seen  . 
--------------------------------------------------------------------------------
3c66ad          17775     397     0.000     0.000     196   8         1 sec
4ca9c3 RYR4045  37000     485     49.246    8.019     135   78        13 sec
4ca555 BCY354   31000     439     48.882    8.207     126   300       0 sec
3d349c          0         0       0.000     0.000     0     253       0 sec
471f50 WZZ4646  37000     486     48.853    8.260     126   341       0 sec
40666b EZY23FE  37975     412     48.688    8.619     312   574       1 sec
4ca5dd IBK524   36000     457     48.526    8.895     228   1055      17 sec
a6eb54          34025     0       0.000     0.000     0     807       0 sec
40078a          37000     0       0.000     0.000     0     1592      0 sec
4b18f3 SWR126P  22425     438     48.636    8.696     190   1744      7 sec

The next thing to do is to build a 1090 MHz antenna for better reception. Two very low cost solutions can be found here and here an overview and some more ideas can be found here.

Update 09/09/2016

Range of the not-optimized DVB-T antenna (left) compared to the 1090 MHz antenna (middle) and selfmade (right)

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Connect HD44780 LCD via USB

I wanted to use one of these cheap hd44780 1602 LCDs (16×2 characters) to display some stats of my headless server. Lcdproc is suitable best for doing this. But how to connect the LCD to to the server? Continue reading

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Serial console on Raspberry Pi

When operating the Pi headless in unknown environments often the only way to access it is to connect via ssh. But what to do if the Pi does not work in that environment better said is not accessible via ssh because it did not get an IP address for example. You don’t want to carry a HDMI-capable monitor and a USB keyboard to avoid that situation! Continue reading

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How to turn an old laptop into an ethernet sniffer

I had to investigate the network traffic of an ethernet-bound device. My plan was to visualize the data sent and received on my laptop using wireshark or similar tools.

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Soil moisture to graph

I did some extensions to my Ardulink MQTT project. My plan was to have a graph of the values of the two analog sensors connected to the Arduino. So this is what I did in general:

  • Deploy the Ardulink sketch to the Arduino
  • Connect your analog sensors to the Arduino
  • Connect the Arduino to a PC
  • On the PC run the Ardulink’s MQTT module. I did by calling “java -jar Mqtt-0.5.1-SNAPSHOT.jar -athms 2000 -ato 0 -a 0 -a 1” to watch analog port 0 and 1
  • Install graphite on a machine
  • Because graphite cannot read mqtt messages you need to install and run mqtt2graphite as well. It subscribes to MQTT and pushes the payload to graphite/carbon. You have to enable UDP in carbon/graphite which is disabled by default!

After that you can open graphite in your browser and configure a view to show the data.

graphite8

This is my example with the two analog sensors, sensor a0 is the soil moisture, a1 is a LDR (measuring the sunlight). As you can see that there were two watering actions (raising a0 values)

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