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                <title>Petter Reinholdtsen - Entries tagged lego</title>
                <description>Entries tagged lego</description>
                <link>http://people.skolelinux.org/pere/blog/</link>

        
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                <title>My own self balancing Lego Segway</title>
                <link>http://people.skolelinux.org/pere/blog/My_own_self_balancing_Lego_Segway.html</link>
                <guid isPermaLink="true">http://people.skolelinux.org/pere/blog/My_own_self_balancing_Lego_Segway.html</guid>
                <pubDate>Fri, 4 Nov 2016 10:15:00 +0100</pubDate>
                <description>&lt;p&gt;A while back I received a Gyro sensor for the NXT
&lt;a href=&quot;mindstorms.lego.com&quot;&gt;Mindstorms&lt;/a&gt; controller as a birthday
present.  It had been on my wishlist for a while, because I wanted to
build a Segway like balancing lego robot.  I had already built
&lt;a href=&quot;http://www.nxtprograms.com/NXT2/segway/&quot;&gt;a simple balancing
robot&lt;/a&gt; with the kids, using the light/color sensor included in the
NXT kit as the balance sensor, but it was not working very well.  It
could balance for a while, but was very sensitive to the light
condition in the room and the reflective properties of the surface and
would fall over after a short while.  I wanted something more robust,
and had
&lt;a href=&quot;https://www.hitechnic.com/cgi-bin/commerce.cgi?preadd=action&amp;key=NGY1044&quot;&gt;the
gyro sensor from HiTechnic&lt;/a&gt; I believed would solve it on my
wishlist for some years before it suddenly showed up as a gift from my
loved ones. :)&lt;/p&gt;

&lt;p&gt;Unfortunately I have not had time to sit down and play with it
since then.  But that changed some days ago, when I was searching for
lego segway information and came across a recipe from HiTechnic for
building
&lt;a href=&quot;http://www.hitechnic.com/blog/gyro-sensor/htway/&quot;&gt;the
HTWay&lt;/a&gt;, a segway like balancing robot.  Build instructions and
&lt;a href=&quot;https://www.hitechnic.com/upload/786-HTWayC.nxc&quot;&gt;source
code&lt;/a&gt; was included, so it was just a question of putting it all
together.  And thanks to the great work of many Debian developers, the
compiler needed to build the source for the NXT is already included in
Debian, so I was read to go in less than an hour.  The resulting robot
do not look very impressive in its simplicity:&lt;/p&gt;

&lt;p align=&quot;center&quot;&gt;&lt;img width=&quot;70%&quot; src=&quot;http://people.skolelinux.org/pere/blog/images/2016-11-04-lego-htway-robot.jpeg&quot;&gt;&lt;/p&gt;

&lt;p&gt;Because I lack the infrared sensor used to control the robot in the
design from HiTechnic, I had to comment out the last task
(taskControl).  I simply placed /* and */ around it get the program
working without that sensor present.  Now it balances just fine until
the battery status run low:&lt;/p&gt;

&lt;p align=&quot;center&quot;&gt;&lt;video width=&quot;70%&quot; controls=&quot;true&quot;&gt;
   &lt;source src=&quot;http://people.skolelinux.org/pere/blog/images/2016-11-04-lego-htway-balancing.ogv&quot; type=&quot;video/ogg&quot;&gt;
&lt;/video&gt;&lt;/p&gt;

&lt;p&gt;Now we would like to teach it how to follow a line and take remote
control instructions using the included Bluetooth receiver in the NXT.&lt;/p&gt;

&lt;p&gt;If you, like me, love LEGO and want to make sure we find the tools
they need to work with LEGO in Debian and all our derivative
distributions like Ubuntu, check out
&lt;a href=&quot;http://wiki.debian.org/LegoDesigners&quot;&gt;the LEGO designers
project page&lt;/a&gt; and join the Debian LEGO team.  Personally I own a
RCX and NXT controller (no EV3), and would like to make sure the
Debian tools needed to program the systems I own work as they
should.&lt;/p&gt;
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                <title>Isenkram, Appstream and udev make life as a LEGO builder easier</title>
                <link>http://people.skolelinux.org/pere/blog/Isenkram__Appstream_and_udev_make_life_as_a_LEGO_builder_easier.html</link>
                <guid isPermaLink="true">http://people.skolelinux.org/pere/blog/Isenkram__Appstream_and_udev_make_life_as_a_LEGO_builder_easier.html</guid>
                <pubDate>Fri, 7 Oct 2016 09:50:00 +0200</pubDate>
                <description>&lt;p&gt;&lt;a href=&quot;http://packages.qa.debian.org/isenkram&quot;&gt;The Isenkram
system&lt;/a&gt; provide a practical and easy way to figure out which
packages support the hardware in a given machine.  The command line
tool &lt;tt&gt;isenkram-lookup&lt;/tt&gt; and the tasksel options provide a
convenient way to list and install packages relevant for the current
hardware during system installation, both user space packages and
firmware packages. The GUI background daemon on the other hand provide
a pop-up proposing to install packages when a new dongle is inserted
while using the computer.  For example, if you plug in a smart card
reader, the system will ask if you want to install &lt;tt&gt;pcscd&lt;/tt&gt; if
that package isn&#39;t already installed, and if you plug in a USB video
camera the system will ask if you want to install &lt;tt&gt;cheese&lt;/tt&gt; if
cheese is currently missing.  This already work just fine.&lt;/p&gt;

&lt;p&gt;But Isenkram depend on a database mapping from hardware IDs to
package names.  When I started no such database existed in Debian, so
I made my own data set and included it with the isenkram package and
made isenkram fetch the latest version of this database from git using
http.  This way the isenkram users would get updated package proposals
as soon as I learned more about hardware related packages.&lt;/p&gt;

&lt;p&gt;The hardware is identified using modalias strings.  The modalias
design is from the Linux kernel where most hardware descriptors are
made available as a strings that can be matched using filename style
globbing.  It handle USB, PCI, DMI and a lot of other hardware related
identifiers.&lt;/p&gt;

&lt;p&gt;The downside to the Isenkram specific database is that there is no
information about relevant distribution / Debian version, making
isenkram propose obsolete packages too.  But along came AppStream, a
cross distribution mechanism to store and collect metadata about
software packages.  When I heard about the proposal, I contacted the
people involved and suggested to add a hardware matching rule using
modalias strings in the specification, to be able to use AppStream for
mapping hardware to packages.  This idea was accepted and AppStream is
now a great way for a package to announce the hardware it support in a
distribution neutral way.  I wrote
&lt;a href=&quot;http://people.skolelinux.org/pere/blog/Using_appstream_with_isenkram_to_install_hardware_related_packages_in_Debian.html&quot;&gt;a
recipe on how to add such meta-information&lt;/a&gt; in a blog post last
December.  If you have a hardware related package in Debian, please
announce the relevant hardware IDs using AppStream.&lt;/p&gt;

&lt;p&gt;In Debian, almost all packages that can talk to a LEGO Mindestorms
RCX or NXT unit, announce this support using AppStream.  The effect is
that when you insert such LEGO robot controller into your Debian
machine, Isenkram will propose to install the packages needed to get
it working.  The intention is that this should allow the local user to
start programming his robot controller right away without having to
guess what packages to use or which permissions to fix.&lt;/p&gt;

&lt;p&gt;But when I sat down with my son the other day to program our NXT
unit using his Debian Stretch computer, I discovered something
annoying.  The local console user (ie my son) did not get access to
the USB device for programming the unit.  This used to work, but no
longer in Jessie and Stretch.  After some investigation and asking
around on #debian-devel, I discovered that this was because udev had
changed the mechanism used to grant access to local devices.  The
ConsoleKit mechanism from &lt;tt&gt;/lib/udev/rules.d/70-udev-acl.rules&lt;/tt&gt;
no longer applied, because LDAP users no longer was added to the
plugdev group during login.  Michael Biebl told me that this method
was obsolete and the new method used ACLs instead.  This was good
news, as the plugdev mechanism is a mess when using a remote user
directory like LDAP.  Using ACLs would make sure a user lost device
access when she logged out, even if the user left behind a background
process which would retain the plugdev membership with the ConsoleKit
setup.  Armed with this knowledge I moved on to fix the access problem
for the LEGO Mindstorms related packages.&lt;/p&gt;

&lt;p&gt;The new system uses a udev tag, &#39;uaccess&#39;.  It can either be
applied directly for a device, or is applied in
/lib/udev/rules.d/70-uaccess.rules for classes of devices.  As the
LEGO Mindstorms udev rules did not have a class, I decided to add the
tag directly in the udev rules files included in the packages.  Here
is one example.  For the nqc C compiler for the RCX, the
&lt;tt&gt;/lib/udev/rules.d/60-nqc.rules&lt;/tt&gt; file now look like this:

&lt;p&gt;&lt;pre&gt;
SUBSYSTEM==&quot;usb&quot;, ACTION==&quot;add&quot;, ATTR{idVendor}==&quot;0694&quot;, ATTR{idProduct}==&quot;0001&quot;, \
    SYMLINK+=&quot;rcx-%k&quot;, TAG+=&quot;uaccess&quot;
&lt;/pre&gt;&lt;/p&gt;

&lt;p&gt;The key part is the &#39;TAG+=&quot;uaccess&quot;&#39; at the end.  I suspect all
packages using plugdev in their /lib/udev/rules.d/ files should be
changed to use this tag (either directly or indirectly via
&lt;tt&gt;70-uaccess.rules&lt;/tt&gt;).  Perhaps a lintian check should be created
to detect this?&lt;/p&gt;

&lt;p&gt;I&#39;ve been unable to find good documentation on the uaccess feature.
It is unclear to me if the uaccess tag is an internal implementation
detail like the udev-acl tag used by
&lt;tt&gt;/lib/udev/rules.d/70-udev-acl.rules&lt;/tt&gt;.  If it is, I guess the
indirect method is the preferred way.  Michael
&lt;a href=&quot;https://github.com/systemd/systemd/issues/4288&quot;&gt;asked for more
documentation from the systemd project&lt;/a&gt; and I hope it will make
this clearer.  For now I use the generic classes when they exist and
is already handled by &lt;tt&gt;70-uaccess.rules&lt;/tt&gt;, and add the tag
directly if no such class exist.&lt;/p&gt;

&lt;p&gt;To learn more about the isenkram system, please check out
&lt;a href=&quot;http://people.skolelinux.org/pere/blog/tags/isenkram/&quot;&gt;my
blog posts tagged isenkram&lt;/a&gt;.&lt;/p&gt;

&lt;p&gt;To help out making life for LEGO constructors in Debian easier,
please join us on our IRC channel
&lt;a href=&quot;irc://irc.debian.org/%23debian-lego&quot;&gt;#debian-lego&lt;/a&gt; and join
the &lt;a href=&quot;https://alioth.debian.org/projects/debian-lego/&quot;&gt;Debian
LEGO team&lt;/a&gt; in the Alioth project we created yesterday.  A mailing
list is not yet created, but we are working on it. :)&lt;/p&gt;

&lt;p&gt;As usual, if you use Bitcoin and want to show your support of my
activities, please send Bitcoin donations to my address
&lt;b&gt;&lt;a href=&quot;bitcoin:15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b&amp;label=PetterReinholdtsenBlog&quot;&gt;15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b&lt;/a&gt;&lt;/b&gt;.&lt;/p&gt;
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                <title>Debian, the Linux distribution of choice for LEGO designers?</title>
                <link>http://people.skolelinux.org/pere/blog/Debian__the_Linux_distribution_of_choice_for_LEGO_designers_.html</link>
                <guid isPermaLink="true">http://people.skolelinux.org/pere/blog/Debian__the_Linux_distribution_of_choice_for_LEGO_designers_.html</guid>
                <pubDate>Sat, 11 May 2013 20:30:00 +0200</pubDate>
                <description>&lt;P&gt;In January,
&lt;a href=&quot;http://people.skolelinux.org/pere/blog/New_IRC_channel_for_LEGO_designers_using_Debian.html&quot;&gt;I
announced a&lt;/a&gt; new &lt;a href=&quot;irc://irc.debian.org/%23debian-lego&quot;&gt;IRC
channel #debian-lego&lt;/a&gt;, for those of us in the Debian and Linux
community interested in &lt;a href=&quot;http://www.lego.com/&quot;&gt;LEGO&lt;/a&gt;, the
marvellous construction system from Denmark.  We also created
&lt;a href=&quot;http://wiki.debian.org/LegoDesigners&quot;&gt;a wiki page&lt;/a&gt; to have
a place to take notes and write down our plans and hopes.  And several
people showed up to help.  I was very happy to see the effect of my
call.  Since the small start, we have a debtags tag
&lt;a href=&quot;http://debtags.debian.net/search/bytag?wl=hardware::hobby:lego&quot;&gt;hardware::hobby:lego&lt;/a&gt;
tag for LEGO related packages, and now count 10 packages related to
LEGO and &lt;a href=&quot;http://mindstorms.lego.com/&quot;&gt;Mindstorms&lt;/a&gt;:&lt;/p&gt;

&lt;p&gt;&lt;table&gt;
&lt;tr&gt;&lt;td&gt;&lt;a href=&quot;http://packages.qa.debian.org/brickos&quot;&gt;brickos&lt;/a&gt;&lt;/td&gt;&lt;td&gt;alternative OS for LEGO Mindstorms RCX. Supports development in C/C++&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td&gt;&lt;a href=&quot;http://packages.qa.debian.org/leocad&quot;&gt;leocad&lt;/a&gt;&lt;/td&gt;&lt;td&gt;virtual brick CAD software&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td&gt;&lt;a href=&quot;http://packages.qa.debian.org/libnxt&quot;&gt;libnxt&lt;/a&gt;&lt;/td&gt;&lt;td&gt;utility library for talking to the LEGO Mindstorms NX&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td&gt;&lt;a href=&quot;http://packages.qa.debian.org/lnpd&quot;&gt;lnpd&lt;/a&gt;&lt;/td&gt;&lt;td&gt;daemon for LNP communication with BrickOS&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td&gt;&lt;a href=&quot;http://packages.qa.debian.org/nbc&quot;&gt;nbc&lt;/a&gt;&lt;/td&gt;&lt;td&gt;compiler for LEGO Mindstorms NXT bricks&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td&gt;&lt;a href=&quot;http://packages.qa.debian.org/nqc&quot;&gt;nqc&lt;/a&gt;&lt;/td&gt;&lt;td&gt;Not Quite C compiler for LEGO Mindstorms RCX&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td&gt;&lt;a href=&quot;http://packages.qa.debian.org/python-nxt&quot;&gt;python-nxt&lt;/a&gt;&lt;/td&gt;&lt;td&gt;python driver/interface/wrapper for the Lego Mindstorms NXT robot&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td&gt;&lt;a href=&quot;http://packages.qa.debian.org/python-nxt-filer&quot;&gt;python-nxt-filer&lt;/a&gt;&lt;/td&gt;&lt;td&gt;simple GUI to manage files on a LEGO Mindstorms NXT&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td&gt;&lt;a href=&quot;http://packages.qa.debian.org/scratch&quot;&gt;scratch&lt;/a&gt;&lt;/td&gt;&lt;td&gt;easy to use programming environment for ages 8 and up&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td&gt;&lt;a href=&quot;http://packages.qa.debian.org/t2n&quot;&gt;t2n&lt;/a&gt;&lt;/td&gt;&lt;td&gt;simple command-line tool for Lego NXT&lt;/td&gt;&lt;/tr&gt;
&lt;/table&gt;&lt;/p&gt;

&lt;p&gt;Some of these are available in Wheezy, and all but one are
currently available in Jessie/testing.  leocad is so far only
available in experimental.&lt;/p&gt;

&lt;p&gt;If you care about LEGO in Debian, please join us on IRC and help
adding the rest of the great free software tools available on Linux
for LEGO designers.&lt;/p&gt;
</description>
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                <title>New IRC channel for LEGO designers using Debian</title>
                <link>http://people.skolelinux.org/pere/blog/New_IRC_channel_for_LEGO_designers_using_Debian.html</link>
                <guid isPermaLink="true">http://people.skolelinux.org/pere/blog/New_IRC_channel_for_LEGO_designers_using_Debian.html</guid>
                <pubDate>Wed, 2 Jan 2013 15:40:00 +0100</pubDate>
                <description>&lt;p&gt;During Christmas, I have worked a bit on the Debian support for
&lt;a href=&quot;http://mindstorms.lego.com/en-us/Default.aspx&quot;&gt;LEGO Mindstorm
NXT&lt;/a&gt;.  My son and I have played a bit with my NXT set, and I
discovered I had to build all the tools myself because none were
already in Debian Squeeze.  If Debian support for LEGO is something
you care about, please join me on the IRC channel
&lt;a href=&quot;irc://irc.debian.org/%23debian-lego&quot;&gt;#debian-lego&lt;/a&gt; (server
irc.debian.org).  There is a lot that could be done to improve the
Debian support for LEGO designers.  For example both CAD software
and Mindstorm compilers are missing. :)&lt;/p&gt;

&lt;p&gt;Update 2012-01-03: A
&lt;a href=&quot;http://wiki.debian.org/LegoDesigners&quot;&gt;project page&lt;/a&gt;
including links to Lego related packages is now available.&lt;/p&gt;
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