seife's assorted rants

Using IRMP with Arduino

seife — Sat, 28 Jan 2012 12:10:24 +0000

I needed to implement an infrared remote control decoder, so certainly I took out my Arduino and hooked up an IR sensor chip to pin 2. Then the interesting thing started. Looking around, I found ladyada’s tutorial on IR sensors. However, the method used there is pretty limited (you basically record a sample of each key signal and then compare the received signal to your samples) and unreliable for many protocols.
Then I found IRMP (german only link, sorry) which is a very versatile IR decoder for many protocols. However, IRMP is made to be used with plain avr-gcc, not from within Arduino’s IDE.
But fixing that was really not very hard.
The results are available on gitorious, project arduino-addons/irmp-arduino, including a simple example sketch to test the decoder.

Note that I’ll probably rebase the git tree whenever something happens in the IRMP SVN repository, so be aware of that in case you make local changes to the code and want to update from my tree.

Have fun!

Decrappify GNOME3 Powermanagement

seife — Thu, 29 Dec 2011 11:01:27 +0000

GNOME3 has actually become quite usable, but I was really annoiyed by the inability to disable actions on “critical low battery” (Additionally, there is no way to define what “critical low battery” is and with a big battery I assume this might well mean that you cannot use the machine anymore even though there is half an hour of juice left). Add to that bnc#738782 which leaves my screen unlocked after suspend and I decided it was time to use someting sane — like xfce4-power-manager — instead.

However, it’s not that easy, as everything power related is hard-coded into the gnome-settings-daemon — and even in different places.

So here is a package with a patch that simply disables the handling of all the power-related keys in the media-keys (!) plugin and additionally prevents the build of the power plugin completely.

Now just start xfce4-power-manager (and maybe use the Evil Status Icon Forever shell extension to make it show up in a visible place).

The patch is here, it is clearly not upstreamable but I’d rather have an ugly hack than an unusable “good solution”

If you don’t want to fight package maintainers…

seife — Fri, 23 Dec 2011 08:51:06 +0000

…then work around the bug.

One example is bug 699400: hwclock is never set correctly when NTP is used (unless it was almost correct before…).

I reported the bug, I argued with the maintainer, it did lead to nothing, the bug was “RESOLVED INVALID” (interesting notion: either it is resolved or it is invalid, then there is nothing to resolve…)

What’s my workaround? I exploit the fact that old SysV init uses bash scripts. The init script which sets the clock does source /etc/sysconfig/clock. Internally, it uses a variable ELEVENMIN_MODE.
So what did I do? Simply add

readonly ELEVENMIN_MODE=no

at the end of /etc/sysconfig/clock.
The script will throw some errors on boot and shutdown due to its inability to change a readonly shell variable, but I can live much better with a harmless warning than with a totally wrong system time at each reboot

Update: Werner has pointed out in the bug that this is totally wrong and will make a mess of your time settings, so use this at your own risk. OTOH I have more than 2000 productive systems here running with this. We had lots of problems before and have no problems anymore after doing it like described here. So at least for me the wrong solution works good.

A trivial systemd unit script: vboxservice.service

seife — Tue, 22 Nov 2011 08:25:42 +0000

In a VirtualBox guest, VBoxService (which is for example responsible for setting the time after a host suspend/resume) is not started on boot. I thought about writing a simple init script to doit (editing the vboxadd init script seemed like a bad idea, since it might get overwritten on updates).
Then I decided to try the “native systemd” way.
Executive summary: it is much easier than with old style SysV init:

# cat /etc/systemd/system/vboxservice.service
[Unit]
Description=VirtualBox guest services

[Service]
ExecStart=/usr/bin/VBoxService -f

[Install]
WantedBy=default.target

Activate with systemctl enable vboxservice.service.

12.1 update - no problems and systemd rocks

seife — Fri, 18 Nov 2011 18:44:32 +0000

Two days ago I updated my home server to 12.1, basically by doing

# cd /etc/zypp/repos.d
# sed -i 's/11.4/12.1/' *
# zypper ref
# zypper -v dup --no-recommends

The only small glitch I had was systemd apparently taking a nap during boot, which made the machine take very long to boot (about 2 minutes).
After filing bug 730776, I found out (with the helpful hint from Frederic), that I still had an invalid swap partition in my fstab. After fixing that, the bootup now really is blazingly fast:
server:~ # systemd-analyze Startup finished in 4116ms (kernel) + 33827ms (userspace) = 37944ms

new avr-gcc packages

seife — Wed, 16 Nov 2011 18:24:18 +0000

Thanks to Volker Kuhlmann, there are now 3 brand new avr-gcc packages in the CrossToolchain:avr repository: avr-gcc-436, avr-gcc-462 and avr-gcc-47-20111105.
The “original” cross-avr-gcc package is still at 4.3.3, as that’s the most tested revision and also it has additional patches that are dropped from the new versions. Those patches add, amongst others, XMEGA support which is not present in the avr-gcc packages. That’s something to improve in the future.

The packages contain a run-avr-gcc-XXX wrapper script (substitute XXX with the 436, 462,…) to make testing the respective compiler very easy.

Have fun testing!

Cool. Censored Mailinglists.

seife — Thu, 10 Nov 2011 15:56:55 +0000

Funny. As soon as someone brings up an unwanted topic, the openSUSE Factory Mailinglist Dictator^WModerator shows up and the rest of the discussion never reaches the list. Without a notice of course.

So that’s what I had to say on the topic, and the Factory list will now probably do without me. This post is just that people have a chance to know why their bugreports will be handled the way they are.

Date: Thu, 10 Nov 2011 07:50:03 +0100
From: Stefan Seyfried
To: opensuse-factory@opensuse.org
Subject: Re: Decision making (Was Re: [opensuse-factory] Kmail 4.7 is not
 shippable in 12.1)
In-Reply-To: <201111091248.27668.markus.s@kdemail.net>

On 09.11.2011 12:48, Markus Slopianka wrote:

> On Mittwoch 09 November 2011 11:45:27 Stefan Seyfried wrote:
>
>> We should simply revert the mistake of making KDE the default desktop.
>
> https://features.opensuse.org/306967
> https://features.opensuse.org/307495
>
> Live with it, vocal minority!

Well, some time ago it was said that openSUSE is a meritrocracy. Those
who do the work get to decide.

It is very easy for people to first vote "make $BROKEN_DESKTOP default"
and later complain that it does not work.

Obviously, all the people wanting to have a certain desktop as a default
need to make it work. If it doesn't, it does not deserve to be the default.

There is even FATE for that: https://features.opensuse.org/312959
Right now, people vote for not having a working desktop.

That's fine with me. Makes bugfixing much easier: either "RESOLVED -
WORKSFORME", or "Component: KDE4-Workspace", "[x] reassign to default
component owner".
I doubt it improves the user experience, but hey, the users voted for
it, so who am I to complain.

My first remotely useful Arduino sketch

seife — Mon, 26 Sep 2011 09:22:15 +0000

I want to use the arduino to interface a small graphic LCD to my satellite set-top-boxes.
The problem with most of the boxes you can buy today is, that they only have a one-line, 12-16 character text-only VFD display and no longer the nice credit-card sized graphic LCDs the old dbox2 or dreamboxes had.
Most new boxes have an USB port,though, so interfacing the LCD via USB is pretty easy.
The code (both arduino and a small test program for the box) is here on gitorious. The protocol is primitive but pretty efficient on RAM and it does recover from errors surprisingly well. The update rate of maybe 10 FPS is enough for this kind of usage.
Now I need to implement some “display driving daemon” which can be interfaced easily with the set-top-box software.

Android Update brings PAN/NAP to Motorola defy

seife — Fri, 09 Sep 2011 05:36:42 +0000

After my summer vacation, I finally did the official update on my defy, which brought the thing to Android 2.2.2.
Since Motorola had obviously done quite some customizing to the original 2.1, not too many obvious differences were there: “Mobile Hotspot” was present before. The design theme (which is something I could not care less about…) was already like 2.2 before and the horrible “MotoBlur” interface is still there, so I thougt “well, it’s mostly some bugfixing under the hood”.

Today, I wanted to finally look into the bluetooth dialup problems I had with the device: NetworkManager was somehow not happy with the responses to some AT commands it got before, resulting in non-working Bluetooth “tethering”. Back then, I did not care too much and chose to just use WiFi instead, but today I decided to look into it.

What can I say? The software update upgraded the Bluetooth tethering from dialup (rfcomm/serial/ppp) to PAN/NAP. Which I like much better as it is more “natural” anyway.

Yet another bug I don’t need to tackle anymore

Update: The same is possible using the “Wireless Tether for Root Users” app from the android market. Just make sure that you start tethering before pairing the device using bluetooth applet, I’m not sure if there is a way to add the PAN interface to an aready paired device, at least I did not find one, so just checking the “Do you want to use the device for internet access” box during pairing is easiest.

Of course I don’t expect this to work with KDE, but it works very well with nm-applet and bluetooth-applet from GNOME.

New toy: Arduino (packages fixed)

seife — Sat, 27 Aug 2011 10:02:10 +0000

So I finally got an arduino or more precisely, a nice starter kit from fritzing.org.

Unboxing pictures are here.

I followed the instructions on installing the software from OBS, but checked the repositories first and found that there were some problems with FACTORY builds in Klaus’ repo.
Additionally, the packages are, even if made to build, not working with the arduino uno thats in the starterkit.

The reasons are

arduino uno has a different USB controller and appears as ACM device, not usbserial
apparently, the avrdude included in CrossToolchain:avr is newer than what the arduino software expects and thus does need another protocol specification
the arduino package sports its own avrdude.conf which does not work with the uno

Of course I fixed all those problems (and submitrequested the fixes back to the “upstream” projects) in the temporary project home:seife:arduino
So now all you should need to do to get the first program uploaded to the uno is:

add the home:seife:arduino repository
add the CrossToolchain:avr repository
zypper install arduino
add your user to the dialout group (we could create some special udev rule case that discovers the arduino and makes the device accessible for group “users”, but that would not help for the other arduinos that come with FT232 usb-serial interfaces)
relogin to activate your dialout group membership
start “arduino” from a terminal (the package is missing a desktop file, I will try to fix that later)

You can also install the fritzing package, but probably better use the package from the Education project than that from Contrib since Education seems to contain a much more recent package.
But for now, everything I did was done using arduino.

Now looking at what is needed to get this to work, I’m wondering if the arduino related packages should just be put into CrossToolchain:avr, or if we should create some project for this Arduino stuff, containing the arduino and fritzing packages and everything needed to support them.
An argument against the “stand alone Arduino project” would be that it duplicates significant build efforts (the cross-avr packages are probably pretty expensive to build).
The pro agument is, that interested users need to add only one repository. If even fritzing is there, they need not add the “Education” repo. This would be good, because adding such big repos which also contain lots of updated “standard” packages (there’s SDL etc. in Education) is certainly not recommended for novice users because of the unpredictable side effects. Note that the CrossToolchain:avr repo is pretty small and does not contain anything that updates system tools or similar, so adding this one should be “mostly harmless”.

I’ll need to think about this and maybe talk with other involved parties at the openSUSE conference in two weeks…