Tag: linux

MEMEX @ Das Netz

Interactive exhibit at “Das Netz” in the “Deutsches Technikmuseum Berlin” – cooperation with Felix Scharstein

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The MEMEX is a historical vision of an american scientist, published in 1945, but never realized. It is a „device for individual use, which is a sort of mechanized private file and library“ based on microfilm technology. The most important idea is the creation of “trails”: links between pages – the first hyperlinks.

This interpretation of the MEMEX vision is based on digital components. The user can search the library, browse documents and create trails in a way that is very close to the original idea. The user interface is very simple but powerful.

My talk on the basic MEMEX idea and this exhibit at the Vintage Computing Festival Berlin 2015 can be watched here (in german language).

Hardware 4x Raspberry Pi, Arduino with 64-button-shield, TFT
PC as database server
Software distributed python-based sofware, communicating over XMLRPC

 

(All images by Bruno Torres Suñén – click image for a larger version)

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Displays

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Camera

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Keyboard

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Keyboard detail

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Display detail

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Keyboard – bottom side


Reading Arexx TL-500 with Python on Linux – Part II

My first script was changed a little bit to get nicer output. It can now log the raw data received from the Arexx unit (in hexadecimal form) and uses separate log files for the sensors. Sensor numbers can be mapped to other names using a dictionary.

I use two TL-3TSN, one TSN-50E (long range) and one TSN-EXT44 (external), all values seem to be correct with this script.

http://download.j-raedler.de/Python/pyArexx/tl500_v0.3.zip


Using KDE’s kwallet with Firefox/Iceweasel

Konqueror is a good browser, but sometimes you need to use Firefox (called Iceweasel on Debian). I discovered a plugin to let FF store its passwords in kwallet, but after installation of the plugin all passwords were gone.

Fortunately you can disable the plugin and the old passwords are still there. So if you want to switch to this plugin you should use the following procedure:

  1. install the Password Exporter plugin
  2. export your passwords to a text file using the plugin
  3. install the kwallet plugin
  4. import your password file using the Password Exporter plugin
  5. check the entries in the section Firefox of your kwallet using the kwalletmanager
  6. don’t forget to delete the exported file

This worked for me.


Reading data from the Arexx TL-500 on Linux

Some days ago I was looking for a temperature monitoring solution for some rooms and 19″-racks at the university. The Arexx TL-500 looked promising and I bought it. Unfortunately there are only Windows drivers available. But some people already analyzed the communication protocol and hacked a simple version of a linux driver:

http://www.algorithm-forge.com/techblog/2010/01/linux-usb-driver-for-the-arexx-tl-500-part-ii/

There’s even a small logger hardware (ARM-based) using this device:

http://rndhax.blogspot.com/2010/03/friendlyarm-mini2440-arexx-tl-500.html

As a python fan I couldn’t resist porting this to python to get a small and flexible script. It can be easily extended to save the data, create charts (maybe using matplotlib) or present a web interface.

By looking at the raw data I noticed that bytes 6 and 7 (maybe more?) contain a time value. Maybe it counts the seconds since the initialization of the device?

The first version of my script is mainly a port of the C program. The script uses pyusb 1.0, a python wrapper for libusb 1.0. You may have to install it manually, most linux distributions come with older versions.

http://download.j-raedler.de/Python/pyArexx/tl500_v0.2.zip

I plan to extend this to a python package using OO, cleaner interfaces, better error handling and more.