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  13  <h1>
  14      <a href="https://people.skolelinux.org/pere/blog/">Petter Reinholdtsen</a>
  15
  16  </h1>
  17
  18 </div>
  19
  20
  21
  22     <div class="entry">
  23       <div class="title"><a href="https://people.skolelinux.org/pere/blog/Is_the_desktop_recommending_your_program_for_opening_its_files_.html">Is the desktop recommending your program for opening its files?</a></div>
  24       <div class="date">29th January 2023</div>
  25       <div class="body"><p>Linux desktop systems
  26 <a href="https://specifications.freedesktop.org/basedir-spec/basedir-spec-latest.html">have
  27 standardized</a> how programs present themselves to the desktop
  28 system.  If a package include a .desktop file in
  29 /usr/share/application, Gnome, KDE, LXDE, Xfce and the other desktop
  30 environments will pick up the file and use its content to generate the
  31 menu of available programs in the system.  A lesser known fact is that
  32 a package can also explain to the desktop system how to recognize the
  33 files created by the program in question, and use it to open these
  34 files on request, for example via a GUI file browser.</p>
  35
  36 <p>A while back I ran into a package that did not tell the desktop
  37 system how to recognize its files and was not used to open its files
  38 in the file browser and fixed it.  In the process I wrote a simple
  39 debian/tests/ script to ensure the setup keep working.  It might be
  40 useful for other packages too, to ensure any future version of the
  41 package keep handling its own files.</p>
  42
  43 <p>For this to work the file format need a useful MIME type that can
  44 be used to identify the format.  If the file format do not yet have a
  45 MIME type, it should define one and preferably also
  46 <a href="https://www.iana.org/assignments/media-types/media-types.xhtml">register
  47 it with IANA</a> to ensure the MIME type string is reserved.</p>
  48
  49 <p>The script uses the <tt>xdg-mime</tt> program from xdg-utils to
  50 query the database of standardized package information and ensure it
  51 return sensible values.  It also need the location of an example file
  52 for xdg-mime to guess the format of.</p>
  53
  54 <pre>
  55 #!/bin/sh
  56 #
  57 # Author: Petter Reinholdtsen
  58 # License: GPL v2 or later at your choice.
  59 #
  60 # Validate the MIME setup, making sure motor types have
  61 # application/vnd.openmotor+yaml associated with them and is connected
  62 # to the openmotor desktop file.
  63
  64 retval=0
  65
  66 mimetype="application/vnd.openmotor+yaml"
  67 testfile="test/data/real/o3100/motor.ric"
  68 mydesktopfile="openmotor.desktop"
  69
  70 filemime="$(xdg-mime query filetype "$testfile")"
  71
  72 if [ "$mimetype" != "$filemime" ] ; then
  73     retval=1
  74     echo "error: xdg-mime claim motor file MIME type is $filemine, not $mimetype"
  75 else
  76     echo "success: xdg-mime report correct mime type $mimetype for motor file"
  77 fi
  78
  79 desktop=$(xdg-mime query default "$mimetype")
  80
  81 if [ "$mydesktopfile" != "$desktop" ]; then
  82     retval=1
  83     echo "error: xdg-mime claim motor file should be handled by $desktop, not $mydesktopfile"
  84 else
  85     echo "success: xdg-mime agree motor file should be handled by $mydesktopfile"
  86 fi
  87
  88 exit $retval
  89 </pre>
  90
  91 <p>It is a simple way to ensure your users are not very surprised when
  92 they try to open one of your file formats in their file browser.</p>
  93
  94 <p>As usual, if you use Bitcoin and want to show your support of my
  95 activities, please send Bitcoin donations to my address
  96 <b><a href="bitcoin:15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b">15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b</a></b>.</p>
  97 </div>
  98       <div class="tags">
  99
 100
 101         Tags: <a href="https://people.skolelinux.org/pere/blog/tags/debian">debian</a>, <a href="https://people.skolelinux.org/pere/blog/tags/english">english</a>.
 102
 103
 104       </div>
 105     </div>
 106     <div class="padding"></div>
 107
 108     <div class="entry">
 109       <div class="title"><a href="https://people.skolelinux.org/pere/blog/Opensnitch__the_application_level_interactive_firewall__heading_into_the_Debian_archive.html">Opensnitch, the application level interactive firewall, heading into the Debian archive</a></div>
 110       <div class="date">22nd January 2023</div>
 111       <div class="body"><p>While reading a
 112 <a href="https://sneak.berlin/20230115/macos-scans-your-local-files-now/">blog
 113 post claiming MacOS X recently started scanning local files and
 114 reporting information about them to Apple</a>, even on a machine where
 115 all such callback features had been disabled, I came across a
 116 description of the Little Snitch application for MacOS X.  It seemed
 117 like a very nice tool to have in the tool box, and I decided to see if
 118 something similar was available for Linux.</p>
 119
 120 <p>It did not take long to find
 121 <a href="https://github.com/evilsocket/opensnitch">the OpenSnitch
 122 package</a>, which has been in development since 2017, and now is in
 123 version 1.5.0.  It has had a
 124 <a href="https://bugs.debian.org/909567">request for Debian
 125 packaging</a> since 2018, but no-one completed the job so far.  Just
 126 for fun, I decided to see if I could help, and I was very happy to
 127 discover that
 128 <a href="https://github.com/evilsocket/opensnitch/issues/304">upstream
 129 want a Debian package too</a>.</p>
 130
 131 <p>After struggling a bit with getting the program to run, figuring
 132 out building Go programs (and a little failed detour to look at eBPF
 133 builds too - help needed), I am very happy to report that I am
 134 sponsoring upstream to maintain the package in Debian, and it has
 135 since this morning been waiting in NEW for the ftpmasters to have a
 136 look.  Perhaps it can get into the archive in time for the Bookworm
 137 release?</p>
 138
 139 <p>As usual, if you use Bitcoin and want to show your support of my
 140 activities, please send Bitcoin donations to my address
 141 <b><a href="bitcoin:15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b">15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b</a></b>.</p>
 142 </div>
 143       <div class="tags">
 144
 145
 146         Tags: <a href="https://people.skolelinux.org/pere/blog/tags/debian">debian</a>, <a href="https://people.skolelinux.org/pere/blog/tags/english">english</a>.
 147
 148
 149       </div>
 150     </div>
 151     <div class="padding"></div>
 152
 153     <div class="entry">
 154       <div class="title"><a href="https://people.skolelinux.org/pere/blog/LinuxCNC_MQTT_publisher_component.html">LinuxCNC MQTT publisher component</a></div>
 155       <div class="date"> 8th January 2023</div>
 156       <div class="body"><p>I watched <a href="https://yewtu.be/watch?v=jmKUV3aNLjk">a 2015
 157 video from Andreas Schiffler</a> the other day, where he set up
 158 <a href="https://linuxcnc.org/">LinuxCNC</a> to send status
 159 information to the MQTT broker IBM Bluemix.  As I also use MQTT for
 160 graphing, it occured to me that a generic MQTT LinuxCNC component
 161 would be useful and I set out to implement it.  Today I got the first
 162 draft limping along and submitted as
 163 <a href="https://github.com/LinuxCNC/linuxcnc/pull/2253">a patch to the
 164 LinuxCNC project</a>.</p>
 165
 166 <p>The simple part was setting up the MQTT publishing code in Python.
 167 I already have set up other parts submitting data to my Mosquito MQTT
 168 broker, so I could reuse that code.  Writing a LinuxCNC component in
 169 Python as new to me, but using existing examples in the code
 170 repository and the extensive documentation, this was fairly straight
 171 forward.  The hardest part was creating a automated test for the
 172 component to ensure it was working.  Testing it in a simulated
 173 LinuxCNC machine proved very useful, as I discovered features I needed
 174 that I had not thought of yet, and adjusted the code quite a bit to
 175 make it easier to test without a operational MQTT broker
 176 available.</p>
 177
 178 <p>The draft is ready and working, but I am unsure which LinuxCNC HAL
 179 pins I should collect and publish by default (in other words, the
 180 default set of information pieces published), and how to get the
 181 machine name from the LinuxCNC INI file.  The latter is a minor
 182 detail, but I expect it would be useful in a setup with several
 183 machines available.  I am hoping for feedback from the experienced
 184 LinuxCNC developers and users, to make the component even better
 185 before it can go into the mainland LinuxCNC code base.</p>
 186
 187 <p>Since I started on the MQTT component, I came across
 188 <a href="https://yewtu.be/watch?v=Bqa2grG0XtA">another video from Kent
 189 VanderVelden</a> where he combine LinuxCNC with a set of screen glasses
 190 controlled by a Raspberry Pi, and it occured to me that it would
 191 be useful for such use cases if LinuxCNC also provided a REST API for
 192 querying its status.  I hope to start on such component once the MQTT
 193 component is working well.</p>
 194
 195 <p>As usual, if you use Bitcoin and want to show your support of my
 196 activities, please send Bitcoin donations to my address
 197 <b><a href="bitcoin:15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b">15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b</a></b>.</p>
 198 </div>
 199       <div class="tags">
 200
 201
 202         Tags: <a href="https://people.skolelinux.org/pere/blog/tags/debian">debian</a>, <a href="https://people.skolelinux.org/pere/blog/tags/english">english</a>, <a href="https://people.skolelinux.org/pere/blog/tags/linuxcnc">linuxcnc</a>, <a href="https://people.skolelinux.org/pere/blog/tags/robot">robot</a>.
 203
 204
 205       </div>
 206     </div>
 207     <div class="padding"></div>
 208
 209     <div class="entry">
 210       <div class="title"><a href="https://people.skolelinux.org/pere/blog/ONVIF_IP_camera_management_tool_finally_in_Debian.html">ONVIF IP camera management tool finally in Debian</a></div>
 211       <div class="date">24th December 2022</div>
 212       <div class="body"><p>Merry Christmas to you all.  Here is a small gift to all those with
 213 IP cameras following the <a href="https://www.onvif.org/">ONVIF
 214 specification</a>.  There is finally a nice command line and GUI tool
 215 in Debian to manage ONVIF IP cameras.  After working with upstream for
 216 a few months and sponsoring the upload, I am very happy to report that
 217 the <a href="https://tracker.debian.org/libonvif">libonvif package</a>
 218 entered Debian Sid last night.</p>
 219
 220 <p>The package provide a C library to communicate with such cameras, a
 221 command line tool to locate and update settings of (like password) the
 222 cameras and a GUI tool to configure and control the units as well as
 223 preview the video from the camera.  Libonvif is available on Both
 224 Linux and Windows and the GUI tool uses the Qt library.  The main
 225 competitors are non-free software, while libonvif is GNU GPL licensed.
 226 I am very glad Debian users in the future can control their cameras
 227 using a free software system provided by Debian.  But the ONVIF world
 228 is full of slightly broken firmware, where the cameras pretend to
 229 follow the ONVIF specification but fail to set some configuration
 230 values or refuse to provide video to more than one recipient at the
 231 time, and the onvif project is quite young and might take a while
 232 before it completely work with your camera.  Upstream seem eager to
 233 improve the library, so handling any broken camera might be just <a
 234 href="https://github.com/sr99622/libonvif/">a bug report away</a>.</p>
 235
 236 <p>The package just cleared NEW, and need a new source only upload
 237 before it can enter testing.  This will happen in the next few
 238 days.</p>
 239
 240 <p>As usual, if you use Bitcoin and want to show your support of my
 241 activities, please send Bitcoin donations to my address
 242 <b><a href="bitcoin:15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b">15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b</a></b>.</p>
 243 </div>
 244       <div class="tags">
 245
 246
 247         Tags: <a href="https://people.skolelinux.org/pere/blog/tags/debian">debian</a>, <a href="https://people.skolelinux.org/pere/blog/tags/english">english</a>, <a href="https://people.skolelinux.org/pere/blog/tags/multimedia">multimedia</a>, <a href="https://people.skolelinux.org/pere/blog/tags/standard">standard</a>, <a href="https://people.skolelinux.org/pere/blog/tags/surveillance">surveillance</a>.
 248
 249
 250       </div>
 251     </div>
 252     <div class="padding"></div>
 253
 254     <div class="entry">
 255       <div class="title"><a href="https://people.skolelinux.org/pere/blog/Managing_and_using_ONVIF_IP_cameras_with_Linux.html">Managing and using ONVIF IP cameras with Linux</a></div>
 256       <div class="date">19th October 2022</div>
 257       <div class="body"><p>Recently I have been looking at how to control and collect data
 258 from a handful IP cameras using Linux.  I both wanted to change their
 259 settings and to make their imagery available via a free software
 260 service under my control.  Here is a summary of the tools I found.</p>
 261
 262 <p>First I had to identify the cameras and their protocols.  As far as
 263 I could tell, they were using some SOAP looking protocol and their
 264 internal web server seem to only work with Microsoft Internet Explorer
 265 with some proprietary binary plugin, which in these days of course is
 266 a security disaster and also made it impossible for me to use the
 267 camera web interface.  Luckily I discovered that the SOAP looking
 268 protocol is actually following <a href="https://www.onvif.org/">the
 269 ONVIF specification</a>, which seem to be supported by a lot of IP
 270 cameras these days.</p>
 271
 272 <p>Once the protocol was identified, I was able to find what appear to
 273 be the most popular way to configure ONVIF cameras, the free software
 274 Windows tool named
 275 <a href="https://sourceforge.net/projects/onvifdm/">ONVIF Device
 276 Manager</a>.  Lacking any other options at the time, I tried
 277 unsuccessfully to get it running using Wine, but was missing a dotnet
 278 40 library and I found no way around it to run it on Linux.</p>
 279
 280 <p>The next tool I found to configure the cameras were a non-free Linux Qt
 281 client <a href="https://www.lingodigit.com/onvif_nvcdemo.html">ONVIF
 282 Device Tool</a>.  I did not like its terms of use, so did not spend
 283 much time on it.</p>
 284
 285 <p>To collect the video and make it available in a web interface, I
 286 found the Zoneminder tool in Debian.  A recent version was able to
 287 automatically detect and configure ONVIF devices, so I could use it to
 288 set up motion detection in and collection of the camera output.  I had
 289 initial problems getting the ONVIF autodetection to work, as both
 290 Firefox and Chromium <a href="https://bugs.debian.org/1001188">refused
 291 the inter-tab communication</a> being used by the Zoneminder web
 292 pages, but managed to get konqueror to work.  Apparently the "Enhanced
 293 Tracking Protection" in Firefox cause the problem.  I ended up
 294 upgrading to the Bookworm edition of Zoneminder in the process to try
 295 to fix the issue, and believe the problem might be solved now.</p>
 296
 297 <p>In the process I came across the nice Linux GUI tool
 298 <a href="https://gitlab.com/caspermeijn/onvifviewer/">ONVIF Viewer</a>
 299 allowing me to preview the camera output and validate the login
 300 passwords required.  Sadly its author has grown tired of maintaining
 301 the software, so it might not see any future updates.  Which is sad,
 302 as the viewer is sightly unstable and the picture tend to lock up.
 303 Note, this lockup might be due to limitations in the cameras and not
 304 the viewer implementation.  I suspect the camera is only able to
 305 provide pictures to one client at the time, and the Zoneminder feed
 306 might interfere with the GUI viewer.  I have
 307 <a href="https://bugs.debian.org/1000820">asked for the tool to be
 308 included in Debian</a>.</p>
 309
 310 <p>Finally, I found what appear to be very nice Linux free software
 311 replacement for the Windows tool, named
 312 <a href="https://github.com/sr99622/libonvif/">libonvif</a>.  It
 313 provide a C library to talk to ONVIF devices as well as a command line
 314 and GUI tool using the library.  Using the GUI tool I was able to change
 315 the admin passwords and update other settings of the cameras.  I have
 316 <a href="https://bugs.debian.org/1021980">asked for the package to be
 317 included in Debian</a>.</p>
 318
 319 <p>As usual, if you use Bitcoin and want to show your support of my
 320 activities, please send Bitcoin donations to my address
 321 <b><a href="bitcoin:15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b">15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b</a></b>.</p>
 322
 323 <p><strong>Update 2022-10-20</strong>: Since my initial publication of
 324 this text, I got several suggestions for more free software Linux
 325 tools.  There is <a href="https://github.com/quatanium/python-onvif">a
 326 ONVIF python library</a> (already
 327 <a href="https://bugs.debian.org/824240">requested into Debian</a>) and
 328 <a href="https://github.com/FalkTannhaeuser/python-onvif-zeep">a python 3
 329 fork</a> using a different SOAP dependency.  There is also
 330 <a href="https://www.home-assistant.io/integrations/onvif/">support for
 331 ONVIF in Home Assistant</a>, and there is an alternative to Zoneminder
 332 called <a href="https://www.shinobi.video/">Shinobi</a>.  The latter
 333 two are not included in Debian either.  I have not tested any of these
 334 so far.</p>
 335 </div>
 336       <div class="tags">
 337
 338
 339         Tags: <a href="https://people.skolelinux.org/pere/blog/tags/debian">debian</a>, <a href="https://people.skolelinux.org/pere/blog/tags/english">english</a>, <a href="https://people.skolelinux.org/pere/blog/tags/multimedia">multimedia</a>, <a href="https://people.skolelinux.org/pere/blog/tags/standard">standard</a>, <a href="https://people.skolelinux.org/pere/blog/tags/surveillance">surveillance</a>.
 340
 341
 342       </div>
 343     </div>
 344     <div class="padding"></div>
 345
 346     <div class="entry">
 347       <div class="title"><a href="https://people.skolelinux.org/pere/blog/Time_to_translate_the_Bullseye_edition_of_the_Debian_Administrator_s_Handbook.html">Time to translate the Bullseye edition of the Debian Administrator's Handbook</a></div>
 348       <div class="date">12th September 2022</div>
 349       <div class="body"><p align="center"><img align="center" src="http://people.skolelinux.org/pere/blog/images/2020-10-20-debian-handbook-nb-testprint.jpeg" width="60%"/></p>
 350
 351 <p>(The picture is of the previous edition.)</p>
 352
 353 <p>Almost two years after the previous Norwegian Bokmål translation of
 354 the "<a href="https://debian-handbook.info/">The Debian Administrator's
 355 Handbook</a>" was published, a new edition is finally being prepared.  The
 356 english text is updated, and it is time to start working on the
 357 translations.  Around 37 percent of the strings have been updated, one
 358 way or another, and the translations starting from a complete Debian Buster
 359 edition now need to bring their translation up from 63% to 100%.  The
 360 complete book is licensed using a Creative Commons license, and has
 361 been published in several languages over the years.  The translations
 362 are done by volunteers to bring Linux in their native tongue.  The
 363 last time I checked, it complete text was available in English,
 364 Norwegian Bokmål, German, Indonesian, Brazil Portuguese and Spanish.
 365 In addition, work has been started for Arabic (Morocco), Catalan,
 366 Chinese (Simplified), Chinese (Traditional), Croatian, Czech, Danish,
 367 Dutch, French, Greek, Italian, Japanese, Korean, Persian, Polish,
 368 Romanian, Russian, Swedish, Turkish and Vietnamese.</p>
 369
 370 <p>The translation is conducted on
 371 <a href="https://hosted.weblate.org/projects/debian-handbook/">the
 372 hosted weblate project page</a>.  Prospective translators are
 373 recommeded to subscribe to
 374 <a href="http://lists.alioth.debian.org/mailman/listinfo/debian-handbook-translators">the
 375 translators mailing list</a> and should also check out
 376 <a href="https://debian-handbook.info/contribute/">the instructions for
 377 contributors</a>.</p>
 378
 379 <p>I am one of the Norwegian Bokmål translators of this book, and we
 380 have just started.  Your contribution is most welcome.</p>
 381
 382 <p>As usual, if you use Bitcoin and want to show your support of my
 383 activities, please send Bitcoin donations to my address
 384 <b><a href="bitcoin:15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b">15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b</a></b>.</p>
 385 </div>
 386       <div class="tags">
 387
 388
 389         Tags: <a href="https://people.skolelinux.org/pere/blog/tags/debian">debian</a>, <a href="https://people.skolelinux.org/pere/blog/tags/debian-handbook">debian-handbook</a>, <a href="https://people.skolelinux.org/pere/blog/tags/english">english</a>.
 390
 391
 392       </div>
 393     </div>
 394     <div class="padding"></div>
 395
 396     <div class="entry">
 397       <div class="title"><a href="https://people.skolelinux.org/pere/blog/Automatic_LinuxCNC_servo_PID_tuning_.html">Automatic LinuxCNC servo PID tuning?</a></div>
 398       <div class="date">16th July 2022</div>
 399       <div class="body"><p>While working on a CNC with servo motors controlled by the
 400 <a href="https://en.wikipedia.org/wiki/LinuxCNC">LinuxCNC</a>
 401 <a href="https://en.wikipedia.org/wiki/PID_controller">PID
 402 controller</a>, I recently had to learn how to tune the collection of values
 403 that control such mathematical machinery that a PID controller is.  It
 404 proved to be a lot harder than I hoped, and I still have not succeeded
 405 in getting the Z PID controller to successfully defy gravity, nor X
 406 and Y to move accurately and reliably.  But while climbing up this
 407 rather steep learning curve, I discovered that some motor control
 408 systems are able to tune their PID controllers.  I got the impression
 409 from the documentation that LinuxCNC were not.  This proved to be not
 410 true.</p>
 411
 412 <p>The LinuxCNC
 413 <a href="http://linuxcnc.org/docs/html/man/man9/pid.9.html">pid
 414 component</a> is the recommended PID controller to use.  It uses eight
 415 constants <tt>Pgain</tt>, <tt>Igain</tt>, <tt>Dgain</tt>,
 416 <tt>bias</tt>, <tt>FF0</tt>, <tt>FF1</tt>, <tt>FF2</tt> and
 417 <tt>FF3</tt> to calculate the output value based on current and wanted
 418 state, and all of these need to have a sensible value for the
 419 controller to behave properly.  Note, there are even more values
 420 involved, theser are just the most important ones.  In my case I need
 421 the X, Y and Z axes to follow the requested path with little error.
 422 This has proved quite a challenge for someone who have never tuned a
 423 PID controller before, but there is at least some help to be found.
 424
 425 <p>I discovered that included in LinuxCNC was this old PID component
 426 at_pid claiming to have auto tuning capabilities.  Sadly it had been
 427 neglected since 2011, and could not be used as a plug in replacement
 428 for the default pid component.  One would have to rewriting the
 429 LinuxCNC HAL setup to test at_pid.  This was rather sad, when I wanted
 430 to quickly test auto tuning to see if it did a better job than me at
 431 figuring out good P, I and D values to use.</p>
 432
 433 <p>I decided to have a look if the situation could be improved.  This
 434 involved trying to understand the code and history of the pid and
 435 at_pid components.  Apparently they had a common ancestor, as code
 436 structure, comments and variable names were quite close to each other.
 437 Sadly this was not reflected in the git history, making it hard to
 438 figure out what really happened.  My guess is that the author of
 439 <a href="https://github.com/LinuxCNC/linuxcnc/blob/master/src/hal/components/at_pid.c">at_pid.c</a>
 440 took a version of
 441 <a href="https://github.com/LinuxCNC/linuxcnc/blob/master/src/hal/components/pid.c">pid.c</a>,
 442 rewrote it to follow the structure he wished pid.c to have, then added
 443 support for auto tuning and finally got it included into the LinuxCNC
 444 repository.  The restructuring and lack of early history made it
 445 harder to figure out which part of the code were relevant to the auto
 446 tuning, and which part of the code needed to be updated to work the
 447 same way as the current pid.c implementation.  I started by trying to
 448 isolate relevant changes in pid.c, and applying them to at_pid.c.  My
 449 aim was to make sure the at_pid component could replace the pid
 450 component with a simple change in the HAL setup loadrt line, without
 451 having to "rewire" the rest of the HAL configuration.  After a few
 452 hours following this approach, I had learned quite a lot about the
 453 code structure of both components, while concluding I was heading down
 454 the wrong rabbit hole, and should get back to the surface and find a
 455 different path.</p>
 456
 457 <p>For the second attempt, I decided to throw away all the PID control
 458 related part of the original at_pid.c, and instead isolate and lift
 459 the auto tuning part of the code and inject it into a copy of pid.c.
 460 This ensured compatibility with the current pid component, while
 461 adding auto tuning as a run time option.  To make it easier to identify
 462 the relevant parts in the future, I wrapped all the auto tuning code
 463 with '#ifdef AUTO_TUNER'.  The end result behave just like the current
 464 pid component by default, as that part of the code is identical.  The
 465 <a href="https://github.com/LinuxCNC/linuxcnc/pull/1820">end result
 466 entered the LinuxCNC master branch</a> a few days ago.</p>
 467
 468 <p>To enable auto tuning, one need to set a few HAL pins in the PID
 469 component.  The most important ones are <tt>tune-effort</tt>,
 470 <tt>tune-mode</tt> and <tt>tune-start</tt>.  But lets take a step
 471 back, and see what the auto tuning code will do.  I do not know the
 472 mathematical foundation of the at_pid algorithm, but from observation
 473 I can tell that the algorithm will, when enabled, produce a square
 474 wave pattern centered around the <tt>bias</tt> value on the output pin
 475 of the PID controller.  This can be seen using the HAL Scope provided
 476 by LinuxCNC.  In my case, this is translated into voltage (+-10V) sent
 477 to the motor controller, which in turn is translated into motor speed.
 478 So at_pid will ask the motor to move the axis back and forth.  The
 479 number of cycles in the pattern is controlled by the
 480 <tt>tune-cycles</tt> pin, and the extremes of the wave pattern is
 481 controlled by the <tt>tune-effort</tt> pin.  Of course, trying to
 482 change the direction of a physical object instantly (as in going
 483 directly from a positive voltage to the equivalent negative voltage)
 484 do not change velocity instantly, and it take some time for the object
 485 to slow down and move in the opposite direction.  This result in a
 486 more smooth movement wave form, as the axis in question were vibrating
 487 back and forth.  When the axis reached the target speed in the
 488 opposing direction, the auto tuner change direction again.  After
 489 several of these changes, the average time delay between the 'peaks'
 490 and 'valleys' of this movement graph is then used to calculate
 491 proposed values for Pgain, Igain and Dgain, and insert them into the
 492 HAL model to use by the pid controller.  The auto tuned settings are
 493 not great, but htye work a lot better than the values I had been able
 494 to cook up on my own, at least for the horizontal X and Y axis.  But I
 495 had to use very small <tt>tune-effort<tt> values, as my motor
 496 controllers error out if the voltage change too quickly.  I've been
 497 less lucky with the Z axis, which is moving a heavy object up and
 498 down, and seem to confuse the algorithm.  The Z axis movement became a
 499 lot better when I introduced a <tt>bias</tt> value to counter the
 500 gravitational drag, but I will have to work a lot more on the Z axis
 501 PID values.</p>
 502
 503 <p>Armed with this knowledge, it is time to look at how to do the
 504 tuning.  Lets say the HAL configuration in question load the PID
 505 component for X, Y and Z like this:</p>
 506
 507 <blockquote><pre>
 508 loadrt pid names=pid.x,pid.y,pid.z
 509 </pre></blockquote>
 510
 511 <p>Armed with the new and improved at_pid component, the new line will
 512 look like this:</p>
 513
 514 <blockquote><pre>
 515 loadrt at_pid names=pid.x,pid.y,pid.z
 516 </pre></blockquote>
 517
 518 <p>The rest of the HAL setup can stay the same.  This work because the
 519 components are referenced by name.  If the component had used count=3
 520 instead, all use of pid.# had to be changed to at_pid.#.</p>
 521
 522 <p>To start tuning the X axis, move the axis to the middle of its
 523 range, to make sure it do not hit anything when it start moving back
 524 and forth.  Next, set the <tt>tune-effort</tt> to a low number in the
 525 output range.  I used 0.1 as my initial value.  Next, assign 1 to the
 526 <tt>tune-mode</tt> value. Note, this will disable the pid controlling
 527 part and feed 0 to the output pin, which in my case initially caused a
 528 lot of drift.  In my case it proved to be a good idea with X and Y to
 529 tune the motor driver to make sure 0 voltage stopped the motor
 530 rotation.  On the other hand, for the Z axis this proved to be a bad
 531 idea, so it will depend on your setup.  It might help to set the
 532 <tt>bias</tt> value to a output value that reduce or eliminate the
 533 axis drift.  Finally, after setting <tt>tune-mode</tt>, set
 534 <tt>tune-start</tt> to 1 to activate the auto tuning.  If all go well,
 535 your axis will vibrate for a few seconds and when it is done, new
 536 values for Pgain, Igain and Dgain will be active.  To test them,
 537 change <tt>tune-mode</tt> back to 0.  Note that this might cause the
 538 machine to suddenly jerk as it bring the axis back to its commanded
 539 position, which it might have drifted away from during tuning.  To
 540 summarize with some halcmd lines:</p>
 541
 542 <blockquote><pre>
 543 setp pid.x.tune-effort 0.1
 544 setp pid.x.tune-mode 1
 545 setp pid.x.tune-start 1
 546 # wait for the tuning to complete
 547 setp pid.x.tune-mode 0
 548 </pre></blockquote>
 549
 550 <p>After doing this task quite a few times while trying to figure out
 551 how to properly tune the PID controllers on the machine in, I decided
 552 to figure out if this process could be automated, and wrote a script
 553 to do the entire tuning process from power on.  The end result will
 554 ensure the machine is powered on and ready to run, home all axis if it
 555 is not already done, check that the extra tuning pins are available,
 556 move the axis to its mid point, run the auto tuning and re-enable the
 557 pid controller when it is done.  It can be run several times.  Check
 558 out the
 559 <a href="https://github.com/SebKuzminsky/MazakVQC1540/blob/bon-dev/scripts/run-auto-pid-tuner">run-auto-pid-tuner</a>
 560 script on github if you want to learn how it is done.</p>
 561
 562 <p>My hope is that this little adventure can inspire someone who know
 563 more about motor PID controller tuning can implement even better
 564 algorithms for automatic PID tuning in LinuxCNC, making life easier
 565 for both me and all the others that want to use LinuxCNC but lack the
 566 in depth knowledge needed to tune PID controllers well.</p>
 567
 568 <p>As usual, if you use Bitcoin and want to show your support of my
 569 activities, please send Bitcoin donations to my address
 570 <b><a href="bitcoin:15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b">15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b</a></b>.</p>
 571 </div>
 572       <div class="tags">
 573
 574
 575         Tags: <a href="https://people.skolelinux.org/pere/blog/tags/3d-printer">3d-printer</a>, <a href="https://people.skolelinux.org/pere/blog/tags/debian">debian</a>, <a href="https://people.skolelinux.org/pere/blog/tags/english">english</a>, <a href="https://people.skolelinux.org/pere/blog/tags/linuxcnc">linuxcnc</a>, <a href="https://people.skolelinux.org/pere/blog/tags/robot">robot</a>.
 576
 577
 578       </div>
 579     </div>
 580     <div class="padding"></div>
 581
 582     <div class="entry">
 583       <div class="title"><a href="https://people.skolelinux.org/pere/blog/My_free_software_activity_of_late__2022_.html">My free software activity of late (2022)</a></div>
 584       <div class="date">20th June 2022</div>
 585       <div class="body"><p>I guess it is time to bring some light on the various free software
 586 and open culture activities and projects I have worked on or been
 587 involved in the last year and a half.</p>
 588
 589 <p>First, lets mention the book
 590 <a href="http://www.hungry.com/~pere/publisher/">releases I managed to
 591 publish</a>.  The Cory Doctorow book "Hvordan knuse
 592 overvåkningskapitalismen" argue that it is not the magic machine
 593 learning of the big technology companies that causes the surveillance
 594 capitalism to thrive, it is the lack of trust busting to enforce
 595 existing anti-monopoly laws.  I also published a family of
 596 dictionaries for machinists, one sorted on the English words, one
 597 sorted on the Norwegian and the last sorted on the North Sámi words.
 598 A bit on the back burner but not forgotten is the Debian
 599 Administrators Handbook, where a new edition is being worked on.  I
 600 have not spent as much time as I want to help bring it to completion,
 601 but hope I will get more spare time to look at it before the end of
 602 the year.</p>
 603
 604 <p>With my Debian had I have spent time on several projects, both
 605 updating existing packages, helping to bring in new packages and
 606 working with upstream projects to try to get them ready to go into
 607 Debian.  The list is rather long, and I will only mention my own
 608 isenkram, openmotor, vlc bittorrent plugin, xprintidle, norwegian
 609 letter style for latex, bs1770gain, and recordmydesktop.  In addition
 610 to these I have sponsored several packages into Debian, like audmes.</p>
 611
 612 <p>The last year I have looked at several infrastructure projects for
 613 collecting meter data and video surveillance recordings.  This include
 614 several ONVIF related tools like onvifviewer and zoneminder as well as
 615 rtl-433, wmbusmeters and rtl-wmbus.</p>
 616
 617 <p>In parallel with this I have looked at fabrication related free
 618 software solutions like pycam and LinuxCNC.  The latter recently
 619 gained improved translation support using po4a and weblate, which was
 620 a harder nut to crack that I had anticipated when I started.</p>
 621
 622 <p>Several hours have been spent translating free software to
 623 Norwegian Bokmål on the Weblate hosted service.  Do not have a
 624 complete list, but you will find my contributions in at least gnucash,
 625 minetest and po4a.</p>
 626
 627 <p>I also spent quite some time on the Norwegian archiving specification
 628 Noark 5, and its companion project Nikita implementing the API
 629 specification for Noark 5.</p>
 630
 631 <p>Recently I have been looking into free software tools to do company
 632 accounting here in Norway., which present an interesting mix between
 633 law, rules, regulations, format specifications and API interfaces.</p>
 634
 635 <p>I guess I should also mention the Norwegian community driven
 636 government interfacing projects Mimes Brønn and Fiksgatami, which have
 637 ended up in a kind of limbo while the future of the projects is being
 638 worked out.</p>
 639
 640 <p>These are just a few of the projects I have been involved it, and
 641 would like to give more visibility.  I'll stop here to avoid delaying
 642 this post.</p>
 643
 644 <p>As usual, if you use Bitcoin and want to show your support of my
 645 activities, please send Bitcoin donations to my address
 646 <b><a href="bitcoin:15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b">15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b</a></b>.</p>
 647 </div>
 648       <div class="tags">
 649
 650
 651         Tags: <a href="https://people.skolelinux.org/pere/blog/tags/english">english</a>.
 652
 653
 654       </div>
 655     </div>
 656     <div class="padding"></div>
 657
 658     <div class="entry">
 659       <div class="title"><a href="https://people.skolelinux.org/pere/blog/LinuxCNC_translators_life_just_got_a_bit_easier.html">LinuxCNC translators life just got a bit easier</a></div>
 660       <div class="date"> 3rd June 2022</div>
 661       <div class="body"><p>Back in oktober last year, when I started looking at the
 662 <a href="https://en.wikipedia.org/wiki/LinuxCNC">LinuxCNC</a> system, I
 663 proposed to change the documentation build system make life easier for
 664 translators.  The original system consisted of independently written
 665 documentation files for each language, with no automated way to track
 666 changes done in other translations and no help for the translators to
 667 know how much was left to translated.  By using
 668 <a href="https://po4a.org/">the po4a system</a> to generate POT and PO
 669 files from the English documentation, this can be improved.  A small
 670 team of LinuxCNC contributors got together and today our labour
 671 finally payed off.  Since a few hours ago, it is now possible to
 672 translate <a href="https://hosted.weblate.org/projects/linuxcnc/">the
 673 LinuxCNC documentation on Weblate</a>, alongside the program itself.</p>
 674
 675 <p>The effort to migrate the documentation to use po4a has been both
 676 slow and frustrating.  I am very happy we finally made it.</p>
 677
 678 <p>As usual, if you use Bitcoin and want to show your support of my
 679 activities, please send Bitcoin donations to my address
 680 <b><a href="bitcoin:15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b">15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b</a></b>.</p>
 681 </div>
 682       <div class="tags">
 683
 684
 685         Tags: <a href="https://people.skolelinux.org/pere/blog/tags/3d-printer">3d-printer</a>, <a href="https://people.skolelinux.org/pere/blog/tags/debian">debian</a>, <a href="https://people.skolelinux.org/pere/blog/tags/english">english</a>, <a href="https://people.skolelinux.org/pere/blog/tags/linuxcnc">linuxcnc</a>, <a href="https://people.skolelinux.org/pere/blog/tags/robot">robot</a>.
 686
 687
 688       </div>
 689     </div>
 690     <div class="padding"></div>
 691
 692     <div class="entry">
 693       <div class="title"><a href="https://people.skolelinux.org/pere/blog/geteltorito_make_CD_firmware_upgrades_a_breeze.html">geteltorito make CD firmware upgrades a breeze</a></div>
 694       <div class="date">20th April 2022</div>
 695       <div class="body"><p>Recently I wanted to upgrade the firmware of my thinkpad, and
 696 located the firmware download page from Lenovo (which annoyingly do
 697 not allow access via Tor, forcing me to hand them more personal
 698 information that I would like).  The
 699 <a href="https://support.lenovo.com/no/en/search?query=thinkpad firmware bios upgrade iso&SearchType=Customer search&searchLocation=Masthead">download
 700 from Lenovo</a> is a bootable ISO image, which is a bit of a problem
 701 when all I got available is a USB memory stick.  I tried booting the
 702 ISO as a USB stick, but this did not work.  But genisoimage came to
 703 the rescue.</p>
 704
 705 <P>The geteltorito program in
 706 <a href="http://tracker.debian.org/cdrkit">the genisoimage binary
 707 package</a> is able to convert the bootable ISO image to a bootable
 708 USB stick using a simple command line recipe, which I then can write
 709 to the most recently inserted USB stick:</p>
 710
 711 <blockquote><pre>
 712 geteltorito -o usbstick.img lenovo-firmware.iso
 713 sudo dd bs=10M if=usbstick.img of=$(ls -tr /dev/sd?|tail -1)
 714 </pre></blockquote>
 715
 716 <p>This USB stick booted the firmware upgrader just fine, and in a few
 717 minutes my machine had the latest and greatest BIOS firmware in place.</p>
 718 </div>
 719       <div class="tags">
 720
 721
 722         Tags: <a href="https://people.skolelinux.org/pere/blog/tags/debian">debian</a>, <a href="https://people.skolelinux.org/pere/blog/tags/english">english</a>.
 723
 724
 725       </div>
 726     </div>
 727     <div class="padding"></div>
 728
 729     <p style="text-align: right;"><a href="index.rss"><img src="https://people.skolelinux.org/pere/blog/xml.gif" alt="RSS feed" width="36" height="14" /></a></p>
 730     <div id="sidebar">
 731
 732
 733
 734 <h2>Archive</h2>
 735 <ul>
 736
 737 <li>2023
 738 <ul>
 739
 740 <li><a href="https://people.skolelinux.org/pere/blog/archive/2023/01/">January (3)</a></li>
 741
 742 </ul></li>
 743
 744 <li>2022
 745 <ul>
 746
 747 <li><a href="https://people.skolelinux.org/pere/blog/archive/2022/02/">February (1)</a></li>
 748
 749 <li><a href="https://people.skolelinux.org/pere/blog/archive/2022/03/">March (3)</a></li>
 750
 751 <li><a href="https://people.skolelinux.org/pere/blog/archive/2022/04/">April (2)</a></li>
 752
 753 <li><a href="https://people.skolelinux.org/pere/blog/archive/2022/06/">June (2)</a></li>
 754
 755 <li><a href="https://people.skolelinux.org/pere/blog/archive/2022/07/">July (1)</a></li>
 756
 757 <li><a href="https://people.skolelinux.org/pere/blog/archive/2022/09/">September (1)</a></li>
 758
 759 <li><a href="https://people.skolelinux.org/pere/blog/archive/2022/10/">October (1)</a></li>
 760
 761 <li><a href="https://people.skolelinux.org/pere/blog/archive/2022/12/">December (1)</a></li>
 762
 763 </ul></li>
 764
 765 <li>2021
 766 <ul>
 767
 768 <li><a href="https://people.skolelinux.org/pere/blog/archive/2021/01/">January (2)</a></li>
 769
 770 <li><a href="https://people.skolelinux.org/pere/blog/archive/2021/02/">February (1)</a></li>
 771
 772 <li><a href="https://people.skolelinux.org/pere/blog/archive/2021/05/">May (1)</a></li>
 773
 774 <li><a href="https://people.skolelinux.org/pere/blog/archive/2021/06/">June (1)</a></li>
 775
 776 <li><a href="https://people.skolelinux.org/pere/blog/archive/2021/07/">July (3)</a></li>
 777
 778 <li><a href="https://people.skolelinux.org/pere/blog/archive/2021/08/">August (1)</a></li>
 779
 780 <li><a href="https://people.skolelinux.org/pere/blog/archive/2021/09/">September (1)</a></li>
 781
 782 <li><a href="https://people.skolelinux.org/pere/blog/archive/2021/10/">October (1)</a></li>
 783
 784 <li><a href="https://people.skolelinux.org/pere/blog/archive/2021/12/">December (1)</a></li>
 785
 786 </ul></li>
 787
 788 <li>2020
 789 <ul>
 790
 791 <li><a href="https://people.skolelinux.org/pere/blog/archive/2020/02/">February (2)</a></li>
 792
 793 <li><a href="https://people.skolelinux.org/pere/blog/archive/2020/03/">March (2)</a></li>
 794
 795 <li><a href="https://people.skolelinux.org/pere/blog/archive/2020/04/">April (2)</a></li>
 796
 797 <li><a href="https://people.skolelinux.org/pere/blog/archive/2020/05/">May (3)</a></li>
 798
 799 <li><a href="https://people.skolelinux.org/pere/blog/archive/2020/06/">June (2)</a></li>
 800
 801 <li><a href="https://people.skolelinux.org/pere/blog/archive/2020/07/">July (1)</a></li>
 802
 803 <li><a href="https://people.skolelinux.org/pere/blog/archive/2020/09/">September (1)</a></li>
 804
 805 <li><a href="https://people.skolelinux.org/pere/blog/archive/2020/10/">October (1)</a></li>
 806
 807 <li><a href="https://people.skolelinux.org/pere/blog/archive/2020/11/">November (1)</a></li>
 808
 809 </ul></li>
 810
 811 <li>2019
 812 <ul>
 813
 814 <li><a href="https://people.skolelinux.org/pere/blog/archive/2019/01/">January (4)</a></li>
 815
 816 <li><a href="https://people.skolelinux.org/pere/blog/archive/2019/02/">February (3)</a></li>
 817
 818 <li><a href="https://people.skolelinux.org/pere/blog/archive/2019/03/">March (3)</a></li>
 819
 820 <li><a href="https://people.skolelinux.org/pere/blog/archive/2019/05/">May (2)</a></li>
 821
 822 <li><a href="https://people.skolelinux.org/pere/blog/archive/2019/06/">June (5)</a></li>
 823
 824 <li><a href="https://people.skolelinux.org/pere/blog/archive/2019/07/">July (2)</a></li>
 825
 826 <li><a href="https://people.skolelinux.org/pere/blog/archive/2019/08/">August (1)</a></li>
 827
 828 <li><a href="https://people.skolelinux.org/pere/blog/archive/2019/09/">September (1)</a></li>
 829
 830 <li><a href="https://people.skolelinux.org/pere/blog/archive/2019/11/">November (1)</a></li>
 831
 832 <li><a href="https://people.skolelinux.org/pere/blog/archive/2019/12/">December (4)</a></li>
 833
 834 </ul></li>
 835
 836 <li>2018
 837 <ul>
 838
 839 <li><a href="https://people.skolelinux.org/pere/blog/archive/2018/01/">January (1)</a></li>
 840
 841 <li><a href="https://people.skolelinux.org/pere/blog/archive/2018/02/">February (5)</a></li>
 842
 843 <li><a href="https://people.skolelinux.org/pere/blog/archive/2018/03/">March (5)</a></li>
 844
 845 <li><a href="https://people.skolelinux.org/pere/blog/archive/2018/04/">April (3)</a></li>
 846
 847 <li><a href="https://people.skolelinux.org/pere/blog/archive/2018/06/">June (2)</a></li>
 848
 849 <li><a href="https://people.skolelinux.org/pere/blog/archive/2018/07/">July (5)</a></li>
 850
 851 <li><a href="https://people.skolelinux.org/pere/blog/archive/2018/08/">August (3)</a></li>
 852
 853 <li><a href="https://people.skolelinux.org/pere/blog/archive/2018/09/">September (3)</a></li>
 854
 855 <li><a href="https://people.skolelinux.org/pere/blog/archive/2018/10/">October (5)</a></li>
 856
 857 <li><a href="https://people.skolelinux.org/pere/blog/archive/2018/11/">November (2)</a></li>
 858
 859 <li><a href="https://people.skolelinux.org/pere/blog/archive/2018/12/">December (4)</a></li>
 860
 861 </ul></li>
 862
 863 <li>2017
 864 <ul>
 865
 866 <li><a href="https://people.skolelinux.org/pere/blog/archive/2017/01/">January (4)</a></li>
 867
 868 <li><a href="https://people.skolelinux.org/pere/blog/archive/2017/02/">February (3)</a></li>
 869
 870 <li><a href="https://people.skolelinux.org/pere/blog/archive/2017/03/">March (5)</a></li>
 871
 872 <li><a href="https://people.skolelinux.org/pere/blog/archive/2017/04/">April (2)</a></li>
 873
 874 <li><a href="https://people.skolelinux.org/pere/blog/archive/2017/06/">June (5)</a></li>
 875
 876 <li><a href="https://people.skolelinux.org/pere/blog/archive/2017/07/">July (1)</a></li>
 877
 878 <li><a href="https://people.skolelinux.org/pere/blog/archive/2017/08/">August (1)</a></li>
 879
 880 <li><a href="https://people.skolelinux.org/pere/blog/archive/2017/09/">September (3)</a></li>
 881
 882 <li><a href="https://people.skolelinux.org/pere/blog/archive/2017/10/">October (5)</a></li>
 883
 884 <li><a href="https://people.skolelinux.org/pere/blog/archive/2017/11/">November (3)</a></li>
 885
 886 <li><a href="https://people.skolelinux.org/pere/blog/archive/2017/12/">December (4)</a></li>
 887
 888 </ul></li>
 889
 890 <li>2016
 891 <ul>
 892
 893 <li><a href="https://people.skolelinux.org/pere/blog/archive/2016/01/">January (3)</a></li>
 894
 895 <li><a href="https://people.skolelinux.org/pere/blog/archive/2016/02/">February (2)</a></li>
 896
 897 <li><a href="https://people.skolelinux.org/pere/blog/archive/2016/03/">March (3)</a></li>
 898
 899 <li><a href="https://people.skolelinux.org/pere/blog/archive/2016/04/">April (8)</a></li>
 900
 901 <li><a href="https://people.skolelinux.org/pere/blog/archive/2016/05/">May (8)</a></li>
 902
 903 <li><a href="https://people.skolelinux.org/pere/blog/archive/2016/06/">June (2)</a></li>
 904
 905 <li><a href="https://people.skolelinux.org/pere/blog/archive/2016/07/">July (2)</a></li>
 906
 907 <li><a href="https://people.skolelinux.org/pere/blog/archive/2016/08/">August (5)</a></li>
 908
 909 <li><a href="https://people.skolelinux.org/pere/blog/archive/2016/09/">September (2)</a></li>
 910
 911 <li><a href="https://people.skolelinux.org/pere/blog/archive/2016/10/">October (3)</a></li>
 912
 913 <li><a href="https://people.skolelinux.org/pere/blog/archive/2016/11/">November (8)</a></li>
 914
 915 <li><a href="https://people.skolelinux.org/pere/blog/archive/2016/12/">December (5)</a></li>
 916
 917 </ul></li>
 918
 919 <li>2015
 920 <ul>
 921
 922 <li><a href="https://people.skolelinux.org/pere/blog/archive/2015/01/">January (7)</a></li>
 923
 924 <li><a href="https://people.skolelinux.org/pere/blog/archive/2015/02/">February (6)</a></li>
 925
 926 <li><a href="https://people.skolelinux.org/pere/blog/archive/2015/03/">March (1)</a></li>
 927
 928 <li><a href="https://people.skolelinux.org/pere/blog/archive/2015/04/">April (4)</a></li>
 929
 930 <li><a href="https://people.skolelinux.org/pere/blog/archive/2015/05/">May (3)</a></li>
 931
 932 <li><a href="https://people.skolelinux.org/pere/blog/archive/2015/06/">June (4)</a></li>
 933
 934 <li><a href="https://people.skolelinux.org/pere/blog/archive/2015/07/">July (6)</a></li>
 935
 936 <li><a href="https://people.skolelinux.org/pere/blog/archive/2015/08/">August (2)</a></li>
 937
 938 <li><a href="https://people.skolelinux.org/pere/blog/archive/2015/09/">September (2)</a></li>
 939
 940 <li><a href="https://people.skolelinux.org/pere/blog/archive/2015/10/">October (9)</a></li>
 941
 942 <li><a href="https://people.skolelinux.org/pere/blog/archive/2015/11/">November (6)</a></li>
 943
 944 <li><a href="https://people.skolelinux.org/pere/blog/archive/2015/12/">December (3)</a></li>
 945
 946 </ul></li>
 947
 948 <li>2014
 949 <ul>
 950
 951 <li><a href="https://people.skolelinux.org/pere/blog/archive/2014/01/">January (2)</a></li>
 952
 953 <li><a href="https://people.skolelinux.org/pere/blog/archive/2014/02/">February (3)</a></li>
 954
 955 <li><a href="https://people.skolelinux.org/pere/blog/archive/2014/03/">March (8)</a></li>
 956
 957 <li><a href="https://people.skolelinux.org/pere/blog/archive/2014/04/">April (7)</a></li>
 958
 959 <li><a href="https://people.skolelinux.org/pere/blog/archive/2014/05/">May (1)</a></li>
 960
 961 <li><a href="https://people.skolelinux.org/pere/blog/archive/2014/06/">June (2)</a></li>
 962
 963 <li><a href="https://people.skolelinux.org/pere/blog/archive/2014/07/">July (2)</a></li>
 964
 965 <li><a href="https://people.skolelinux.org/pere/blog/archive/2014/08/">August (2)</a></li>
 966
 967 <li><a href="https://people.skolelinux.org/pere/blog/archive/2014/09/">September (5)</a></li>
 968
 969 <li><a href="https://people.skolelinux.org/pere/blog/archive/2014/10/">October (6)</a></li>
 970
 971 <li><a href="https://people.skolelinux.org/pere/blog/archive/2014/11/">November (3)</a></li>
 972
 973 <li><a href="https://people.skolelinux.org/pere/blog/archive/2014/12/">December (5)</a></li>
 974
 975 </ul></li>
 976
 977 <li>2013
 978 <ul>
 979
 980 <li><a href="https://people.skolelinux.org/pere/blog/archive/2013/01/">January (11)</a></li>
 981
 982 <li><a href="https://people.skolelinux.org/pere/blog/archive/2013/02/">February (9)</a></li>
 983
 984 <li><a href="https://people.skolelinux.org/pere/blog/archive/2013/03/">March (9)</a></li>
 985
 986 <li><a href="https://people.skolelinux.org/pere/blog/archive/2013/04/">April (6)</a></li>
 987
 988 <li><a href="https://people.skolelinux.org/pere/blog/archive/2013/05/">May (9)</a></li>
 989
 990 <li><a href="https://people.skolelinux.org/pere/blog/archive/2013/06/">June (10)</a></li>
 991
 992 <li><a href="https://people.skolelinux.org/pere/blog/archive/2013/07/">July (7)</a></li>
 993
 994 <li><a href="https://people.skolelinux.org/pere/blog/archive/2013/08/">August (3)</a></li>
 995
 996 <li><a href="https://people.skolelinux.org/pere/blog/archive/2013/09/">September (5)</a></li>
 997
 998 <li><a href="https://people.skolelinux.org/pere/blog/archive/2013/10/">October (7)</a></li>
 999
1000 <li><a href="https://people.skolelinux.org/pere/blog/archive/2013/11/">November (9)</a></li>
1001
1002 <li><a href="https://people.skolelinux.org/pere/blog/archive/2013/12/">December (3)</a></li>
1003
1004 </ul></li>
1005
1006 <li>2012
1007 <ul>
1008
1009 <li><a href="https://people.skolelinux.org/pere/blog/archive/2012/01/">January (7)</a></li>
1010
1011 <li><a href="https://people.skolelinux.org/pere/blog/archive/2012/02/">February (10)</a></li>
1012
1013 <li><a href="https://people.skolelinux.org/pere/blog/archive/2012/03/">March (17)</a></li>
1014
1015 <li><a href="https://people.skolelinux.org/pere/blog/archive/2012/04/">April (12)</a></li>
1016
1017 <li><a href="https://people.skolelinux.org/pere/blog/archive/2012/05/">May (12)</a></li>
1018
1019 <li><a href="https://people.skolelinux.org/pere/blog/archive/2012/06/">June (20)</a></li>
1020
1021 <li><a href="https://people.skolelinux.org/pere/blog/archive/2012/07/">July (17)</a></li>
1022
1023 <li><a href="https://people.skolelinux.org/pere/blog/archive/2012/08/">August (6)</a></li>
1024
1025 <li><a href="https://people.skolelinux.org/pere/blog/archive/2012/09/">September (9)</a></li>
1026
1027 <li><a href="https://people.skolelinux.org/pere/blog/archive/2012/10/">October (17)</a></li>
1028
1029 <li><a href="https://people.skolelinux.org/pere/blog/archive/2012/11/">November (10)</a></li>
1030
1031 <li><a href="https://people.skolelinux.org/pere/blog/archive/2012/12/">December (7)</a></li>
1032
1033 </ul></li>
1034
1035 <li>2011
1036 <ul>
1037
1038 <li><a href="https://people.skolelinux.org/pere/blog/archive/2011/01/">January (16)</a></li>
1039
1040 <li><a href="https://people.skolelinux.org/pere/blog/archive/2011/02/">February (6)</a></li>
1041
1042 <li><a href="https://people.skolelinux.org/pere/blog/archive/2011/03/">March (6)</a></li>
1043
1044 <li><a href="https://people.skolelinux.org/pere/blog/archive/2011/04/">April (7)</a></li>
1045
1046 <li><a href="https://people.skolelinux.org/pere/blog/archive/2011/05/">May (3)</a></li>
1047
1048 <li><a href="https://people.skolelinux.org/pere/blog/archive/2011/06/">June (2)</a></li>
1049
1050 <li><a href="https://people.skolelinux.org/pere/blog/archive/2011/07/">July (7)</a></li>
1051
1052 <li><a href="https://people.skolelinux.org/pere/blog/archive/2011/08/">August (6)</a></li>
1053
1054 <li><a href="https://people.skolelinux.org/pere/blog/archive/2011/09/">September (4)</a></li>
1055
1056 <li><a href="https://people.skolelinux.org/pere/blog/archive/2011/10/">October (2)</a></li>
1057
1058 <li><a href="https://people.skolelinux.org/pere/blog/archive/2011/11/">November (3)</a></li>
1059
1060 <li><a href="https://people.skolelinux.org/pere/blog/archive/2011/12/">December (1)</a></li>
1061
1062 </ul></li>
1063
1064 <li>2010
1065 <ul>
1066
1067 <li><a href="https://people.skolelinux.org/pere/blog/archive/2010/01/">January (2)</a></li>
1068
1069 <li><a href="https://people.skolelinux.org/pere/blog/archive/2010/02/">February (1)</a></li>
1070
1071 <li><a href="https://people.skolelinux.org/pere/blog/archive/2010/03/">March (3)</a></li>
1072
1073 <li><a href="https://people.skolelinux.org/pere/blog/archive/2010/04/">April (3)</a></li>
1074
1075 <li><a href="https://people.skolelinux.org/pere/blog/archive/2010/05/">May (9)</a></li>
1076
1077 <li><a href="https://people.skolelinux.org/pere/blog/archive/2010/06/">June (14)</a></li>
1078
1079 <li><a href="https://people.skolelinux.org/pere/blog/archive/2010/07/">July (12)</a></li>
1080
1081 <li><a href="https://people.skolelinux.org/pere/blog/archive/2010/08/">August (13)</a></li>
1082
1083 <li><a href="https://people.skolelinux.org/pere/blog/archive/2010/09/">September (7)</a></li>
1084
1085 <li><a href="https://people.skolelinux.org/pere/blog/archive/2010/10/">October (9)</a></li>
1086
1087 <li><a href="https://people.skolelinux.org/pere/blog/archive/2010/11/">November (13)</a></li>
1088
1089 <li><a href="https://people.skolelinux.org/pere/blog/archive/2010/12/">December (12)</a></li>
1090
1091 </ul></li>
1092
1093 <li>2009
1094 <ul>
1095
1096 <li><a href="https://people.skolelinux.org/pere/blog/archive/2009/01/">January (8)</a></li>
1097
1098 <li><a href="https://people.skolelinux.org/pere/blog/archive/2009/02/">February (8)</a></li>
1099
1100 <li><a href="https://people.skolelinux.org/pere/blog/archive/2009/03/">March (12)</a></li>
1101
1102 <li><a href="https://people.skolelinux.org/pere/blog/archive/2009/04/">April (10)</a></li>
1103
1104 <li><a href="https://people.skolelinux.org/pere/blog/archive/2009/05/">May (9)</a></li>
1105
1106 <li><a href="https://people.skolelinux.org/pere/blog/archive/2009/06/">June (3)</a></li>
1107
1108 <li><a href="https://people.skolelinux.org/pere/blog/archive/2009/07/">July (4)</a></li>
1109
1110 <li><a href="https://people.skolelinux.org/pere/blog/archive/2009/08/">August (3)</a></li>
1111
1112 <li><a href="https://people.skolelinux.org/pere/blog/archive/2009/09/">September (1)</a></li>
1113
1114 <li><a href="https://people.skolelinux.org/pere/blog/archive/2009/10/">October (2)</a></li>
1115
1116 <li><a href="https://people.skolelinux.org/pere/blog/archive/2009/11/">November (3)</a></li>
1117
1118 <li><a href="https://people.skolelinux.org/pere/blog/archive/2009/12/">December (3)</a></li>
1119
1120 </ul></li>
1121
1122 <li>2008
1123 <ul>
1124
1125 <li><a href="https://people.skolelinux.org/pere/blog/archive/2008/11/">November (5)</a></li>
1126
1127 <li><a href="https://people.skolelinux.org/pere/blog/archive/2008/12/">December (7)</a></li>
1128
1129 </ul></li>
1130
1131 </ul>
1132
1133
1134
1135 <h2>Tags</h2>
1136 <ul>
1137
1138  <li><a href="https://people.skolelinux.org/pere/blog/tags/3d-printer">3d-printer (19)</a></li>
1139
1140  <li><a href="https://people.skolelinux.org/pere/blog/tags/amiga">amiga (1)</a></li>
1141
1142  <li><a href="https://people.skolelinux.org/pere/blog/tags/aros">aros (1)</a></li>
1143
1144  <li><a href="https://people.skolelinux.org/pere/blog/tags/bankid">bankid (4)</a></li>
1145
1146  <li><a href="https://people.skolelinux.org/pere/blog/tags/betalkontant">betalkontant (9)</a></li>
1147
1148  <li><a href="https://people.skolelinux.org/pere/blog/tags/bitcoin">bitcoin (12)</a></li>
1149
1150  <li><a href="https://people.skolelinux.org/pere/blog/tags/bootsystem">bootsystem (17)</a></li>
1151
1152  <li><a href="https://people.skolelinux.org/pere/blog/tags/bsa">bsa (2)</a></li>
1153
1154  <li><a href="https://people.skolelinux.org/pere/blog/tags/chrpath">chrpath (2)</a></li>
1155
1156  <li><a href="https://people.skolelinux.org/pere/blog/tags/debian">debian (187)</a></li>
1157
1158  <li><a href="https://people.skolelinux.org/pere/blog/tags/debian edu">debian edu (159)</a></li>
1159
1160  <li><a href="https://people.skolelinux.org/pere/blog/tags/debian-handbook">debian-handbook (9)</a></li>
1161
1162  <li><a href="https://people.skolelinux.org/pere/blog/tags/digistan">digistan (11)</a></li>
1163
1164  <li><a href="https://people.skolelinux.org/pere/blog/tags/dld">dld (18)</a></li>
1165
1166  <li><a href="https://people.skolelinux.org/pere/blog/tags/docbook">docbook (30)</a></li>
1167
1168  <li><a href="https://people.skolelinux.org/pere/blog/tags/drivstoffpriser">drivstoffpriser (4)</a></li>
1169
1170  <li><a href="https://people.skolelinux.org/pere/blog/tags/english">english (443)</a></li>
1171
1172  <li><a href="https://people.skolelinux.org/pere/blog/tags/fiksgatami">fiksgatami (23)</a></li>
1173
1174  <li><a href="https://people.skolelinux.org/pere/blog/tags/fildeling">fildeling (14)</a></li>
1175
1176  <li><a href="https://people.skolelinux.org/pere/blog/tags/freeculture">freeculture (34)</a></li>
1177
1178  <li><a href="https://people.skolelinux.org/pere/blog/tags/freedombox">freedombox (9)</a></li>
1179
1180  <li><a href="https://people.skolelinux.org/pere/blog/tags/frikanalen">frikanalen (20)</a></li>
1181
1182  <li><a href="https://people.skolelinux.org/pere/blog/tags/h264">h264 (20)</a></li>
1183
1184  <li><a href="https://people.skolelinux.org/pere/blog/tags/intervju">intervju (43)</a></li>
1185
1186  <li><a href="https://people.skolelinux.org/pere/blog/tags/isenkram">isenkram (16)</a></li>
1187
1188  <li><a href="https://people.skolelinux.org/pere/blog/tags/kart">kart (23)</a></li>
1189
1190  <li><a href="https://people.skolelinux.org/pere/blog/tags/kodi">kodi (4)</a></li>
1191
1192  <li><a href="https://people.skolelinux.org/pere/blog/tags/ldap">ldap (9)</a></li>
1193
1194  <li><a href="https://people.skolelinux.org/pere/blog/tags/lego">lego (5)</a></li>
1195
1196  <li><a href="https://people.skolelinux.org/pere/blog/tags/lenker">lenker (8)</a></li>
1197
1198  <li><a href="https://people.skolelinux.org/pere/blog/tags/linuxcnc">linuxcnc (4)</a></li>
1199
1200  <li><a href="https://people.skolelinux.org/pere/blog/tags/lsdvd">lsdvd (2)</a></li>
1201
1202  <li><a href="https://people.skolelinux.org/pere/blog/tags/ltsp">ltsp (1)</a></li>
1203
1204  <li><a href="https://people.skolelinux.org/pere/blog/tags/madewithcc">madewithcc (3)</a></li>
1205
1206  <li><a href="https://people.skolelinux.org/pere/blog/tags/mesh network">mesh network (8)</a></li>
1207
1208  <li><a href="https://people.skolelinux.org/pere/blog/tags/multimedia">multimedia (44)</a></li>
1209
1210  <li><a href="https://people.skolelinux.org/pere/blog/tags/nice free software">nice free software (13)</a></li>
1211
1212  <li><a href="https://people.skolelinux.org/pere/blog/tags/noark5">noark5 (23)</a></li>
1213
1214  <li><a href="https://people.skolelinux.org/pere/blog/tags/norsk">norsk (320)</a></li>
1215
1216  <li><a href="https://people.skolelinux.org/pere/blog/tags/nuug">nuug (198)</a></li>
1217
1218  <li><a href="https://people.skolelinux.org/pere/blog/tags/offentlig innsyn">offentlig innsyn (40)</a></li>
1219
1220  <li><a href="https://people.skolelinux.org/pere/blog/tags/open311">open311 (2)</a></li>
1221
1222  <li><a href="https://people.skolelinux.org/pere/blog/tags/opphavsrett">opphavsrett (75)</a></li>
1223
1224  <li><a href="https://people.skolelinux.org/pere/blog/tags/personvern">personvern (114)</a></li>
1225
1226  <li><a href="https://people.skolelinux.org/pere/blog/tags/raid">raid (2)</a></li>
1227
1228  <li><a href="https://people.skolelinux.org/pere/blog/tags/reactos">reactos (1)</a></li>
1229
1230  <li><a href="https://people.skolelinux.org/pere/blog/tags/reprap">reprap (11)</a></li>
1231
1232  <li><a href="https://people.skolelinux.org/pere/blog/tags/rfid">rfid (3)</a></li>
1233
1234  <li><a href="https://people.skolelinux.org/pere/blog/tags/robot">robot (17)</a></li>
1235
1236  <li><a href="https://people.skolelinux.org/pere/blog/tags/rss">rss (1)</a></li>
1237
1238  <li><a href="https://people.skolelinux.org/pere/blog/tags/ruter">ruter (7)</a></li>
1239
1240  <li><a href="https://people.skolelinux.org/pere/blog/tags/scraperwiki">scraperwiki (2)</a></li>
1241
1242  <li><a href="https://people.skolelinux.org/pere/blog/tags/sikkerhet">sikkerhet (59)</a></li>
1243
1244  <li><a href="https://people.skolelinux.org/pere/blog/tags/sitesummary">sitesummary (4)</a></li>
1245
1246  <li><a href="https://people.skolelinux.org/pere/blog/tags/skepsis">skepsis (5)</a></li>
1247
1248  <li><a href="https://people.skolelinux.org/pere/blog/tags/standard">standard (74)</a></li>
1249
1250  <li><a href="https://people.skolelinux.org/pere/blog/tags/stavekontroll">stavekontroll (7)</a></li>
1251
1252  <li><a href="https://people.skolelinux.org/pere/blog/tags/stortinget">stortinget (14)</a></li>
1253
1254  <li><a href="https://people.skolelinux.org/pere/blog/tags/surveillance">surveillance (64)</a></li>
1255
1256  <li><a href="https://people.skolelinux.org/pere/blog/tags/sysadmin">sysadmin (5)</a></li>
1257
1258  <li><a href="https://people.skolelinux.org/pere/blog/tags/usenix">usenix (2)</a></li>
1259
1260  <li><a href="https://people.skolelinux.org/pere/blog/tags/valg">valg (9)</a></li>
1261
1262  <li><a href="https://people.skolelinux.org/pere/blog/tags/verkidetfri">verkidetfri (20)</a></li>
1263
1264  <li><a href="https://people.skolelinux.org/pere/blog/tags/video">video (77)</a></li>
1265
1266  <li><a href="https://people.skolelinux.org/pere/blog/tags/vitenskap">vitenskap (4)</a></li>
1267
1268  <li><a href="https://people.skolelinux.org/pere/blog/tags/web">web (42)</a></li>
1269
1270 </ul>
1271
1272
1273     </div>
1274     <p style="text-align: right">
1275  Created by <a href="http://steve.org.uk/Software/chronicle">Chronicle v4.6</a>
1276 </p>
1277
1278   </body>
1279 </html>