Filed under: freelancer | My place to share some bits and bytes

Angular rate driver work finished

2010-04-26T12:30:18+02:00

Last week I finished the contract work for the angular rate drivers I mentioned in my last post.

During the final meeting we also verified that the output of the sensors are what we expect them to be. While coding them I was able to check that I'm using the right registers, values are changing when I turn the device, but I had no test equipment to see if the measurement is really correct.

At the DLR we could use an angular rate table for this. The device itself was mounted on the rotating table with power and data connection on sliding contacts. Some pictures of the setup can be found here.

From the measurement point the MLX90609 and the SAR100 variant we used are quite different. The MLX is capable of 300 degree per second while the SAR100 was able to measure 1500. In our test we even had good results with 1800. During this testing we found a bit different offsets as described in the data sheets but still pretty close to what we expected.

I'm really looking forward to the launch of the rocket to hear about the results the sensors produced and how it compares to the big money equipment that it used for the flight control of the rocket. Once the rocket is back and the data is analyzed I also should be able to get a board back and do my part on getting the drivers into mainline. For now I have posted them as demo to the openmoko kernel list.

Freerunner preparing for his second outer space trip

2010-02-28T15:40:36+02:00

In May last year the Freerunner had its debut in outer space. The Mobile Rocket Base department of the German Aerospace Center launched a research rocket into the aerospace (140Km height). On board was the pictured Freerunner. Although the metal case you can see on the picture is new and was not used.

The mission of the rocket was to experiment with materials physics under conditions of weightlessness. The Freerunner had nothing to do with this experiments and was only on board to verify that it survives the launch, travel and landing. Battery, GSM and GPS antenna has been removed before launch. Everything survived. During the flight the accelerometers have been used to collect measurements.

In May this year it will enjoy its second trip into space. The case was designed and build to offer space for the Freerunner as well as an extension board connected to it. The board is connected to the debug board connector of the Freerunner which offers a SPI and an I2C bus. It was designed to hold different sensors the Freerunner does not offer and is equipped with a BMP085 pressure sensor and two gyroscopes. The Melexis MLX90609 and the Sensonor SAR100.

Over the next month I'll working on drivers for these two gyroscopes and after the flight we will see if the chips survived and if the data they had produced will show that they are good enough for further testing.

All in all this shows pretty nicely how an open device with available schematics, CAD files and hardware interfaces can serve together with an open software stack for vertical markets. Be it for research purpose like in this case or a crazy business idea on the other side. The fact that you have all resources to understand the electrical design as well as being able to make changes over the complete software stack brings you into the position to easily adapt it for your needs.

Some more picture with a higher resolution can be found here.

UPDATE: Fix typos and rewrite some parts so people have a chance to understand it.

Leaving Openmoko aka Free Your Self

2008-04-17T22:11:17+02:00

It's over 13 months now since I started to work for OpenMoko. Wednesday was my last day.

I'm not leaving with bad feelings. Still over the last months I disagreed with decisions and directions, got frustrated with the work I had to do. Not the best conditions for a productive work environment.

However I still like to see OpenMoko success. As open as possible mobile phone hardware on which I can flash all kind of software I like. Not fighting against vendor policies but having almost all options I like. Still sounds great to me.

Over the last 13 months I learned a lot. For both, coding and business. Working with some great people from the FOSS community from all over the world and with great taiwanese engineers. (Watch out for these guys, they are awesome but shy) Made new friends and had to deal with an interesting different culture.

It was an awesome but exhausting trip. It's over for now.

I plan to do no paid work for the next 1-2 months, perhaps even longer. In this time-frame I need to come back to the study life I had before and take some rest. Read some good books, hang out with friends and don't worry about deadlines.

After that we will see what kind of work will come in. At least it must be not as much time consuming as OpenMoko was. Need to focus on my studies.

Mobile Developer Days 2007 are over

2007-09-03T13:53:16+02:00

Currently I'm with Mickey in a train back to Germany from Denmark. The last days I participated the Mobile Developer Days 2007. In contrast to the most other conferences I attend this one was not only about FOSS but more about developing software for mobile devices. Write applications in Python, Java, Open C, examples for location enabled applications, VoIP and rapid prototyping for artist are just a small extract of the program.

Mickey and me gave our talks about Open{Moko,EZX} and presented the community view in discussions.

Besides the different focus the event was also a lot smaller then the ones I usually attend. Around 40 people. So most of the attendees were speaker as well. Mixed up with the fact that many of the people are doing research in this area gave the conference a academic touch.

In the last weeks Mickey and me pondered if we really should attend as our travel and working schedules are pretty full, we did not got plane tickets and had to go two 10 hours train rides, etc.

In the end I'm happy we decided to go. Besides the talks especially the small group of people was a good place for interesting and informative discussions. Coming from the FOSS world and doing not much business besides OpenMoko it was quite interesting for me what people with a more commercial background are doing with mobile devices and what benefits and drawbacks they see in using FOSS for example.

During the days and nights we had some working session with normal OpenMoko stuff but also some hours on catching up with OpenEZX stuff. But that's another blogpost.

Conferences ahead. Going to RMLL and GUADEC.

2007-07-07T19:02:08+02:00

After having a busy time with university, OpenMoko and getting my partime freelance going I now are getting more relaxed and looking forward to the next two weeks which I will spend mostly on two conferences.

Next week starts with my flight to France. I'm giving a talk about free software on mobile phones. It covers mostly OpenEZX and OpenMoko, but also tries to give an overview about other projects in this area. As my talk is at the first day I'm looking forward for the other talks, visit Amiens and doing having some time for OpenMoko related work.

Coming back from France means having a half day and a night at home and jumping over to England again. GUADEC will be full of meeting people, having fun and making plans for the upcoming month. I'll fly together with Daniel and his girlfriend and meet up Mickey in Birmingham. But besides OpenMoko related discussions I really looking forward to meet people behind Gnome.

Cheap and powerfull copy and printer laser combination.

2007-03-24T03:50:43+02:00

For my small home office I searched for a cheap duplex laser printer which can also make copies.

After some research I found the Brother DCP-8065DN. The price on the website is too high. I got mine for 490 Euro.

That is really cheap if you look at the features the beast offers me:

Duplex laser printer with PostScript 3 and some other emulations.
Parallel, USB 2.0 and network connection. (Even IPv6. cool)
Duplex copies up to 50 sheets at once.
Scan sheets, put them into a PDF or leave as JPEG and upload it to a FTP server or send per mail.
Perhaps network scanning. Need to check linux support here, but this has no priority at the moment.

Besides the printer and copy features especially the duplex up to 50 sheets scan feature is just great.

Take a pile of paper you like to get rid of. Put it into the machine and you get a nice PDF uploaded to your FTP. Great. :)