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Simon's blog Posts

Post Danmark Rundt 2013

Last week, one of the largest annual sports events in Denmark took place – Post Danmark Rundt 2013. Like previous years, one of the stages passed through my home town Vejle, including several climbs up the rather steep Kiddesvej, where I (together with my camera and quite a lot of other spectators) had found a good spot to get a look at the action. Getting some decent shots proved harder than hoped though – getting composition and focus right, while also trying not to hit any of the riders with my zoomed-in tele-lens ended up giving me quite a lot…

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My youtube channel

My headline currently talks about “computers, robots and photos”, and while there has already been posts on the first and the latter, robots have been missing. Mostly due to my current job at Newtec not having quite the same opportunities for messing around with robots, as my old job in Robolab at the University of Southern Denmark. In any case, during my time in Robolab, I created quite a few videos of my projects, which can still be found on my youtube channel. I’ll see if I can get some videos of some more current projects put together also in…

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Amazing sunset

Had an amazing sunset on the last day of my summer-holiday, with the sun basically shining up on the clouds from below. Lying on the couch watching Top Gear, I had to hurry outside with the camera once I noticed what was going on. Managed to get a few shots, although they don’t really do it justice.

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Egeskov Castle

As summer is upon Denmark (and holiday is upon me), I chose to spend the day at Egeskov Castle. Took the bike, which gave me a nice 2 hour ride in each direction. Weather was great, although a pure blue sky does look rather dull in a photo. I’ve had too many summers with bad weather in Denmark to be able to complain about that though ;)

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Real-time Linux Kernel drivers – Part 3, the better and best implementations

– continued from part 2.

My first attempt at creating a 100 Hz real-time Linux kernel loop did not work as expected. After getting some good pointers from the linux-rt-users mailing list, and doing some further investigations myself, I decided to reimplement the loop using usleep_range() (further described here). This function basically just sleeps for a specified time (given a minimum and a maximum time to sleep), and thus does not need to have callbacks or similar specified. It should therefore be straight-forward to just create a new thread calling usleep_range() after each iteration, and then schedule it with the real-time scheduler.

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Real-time Linux Kernel drivers – Part 1, the backstory

At work I recently had to create a set of real-time Linux drivers for our custom hardware board. I’ve found it to be an interesting experience that I’d like to share – especially since it took some help from the PREEMPT_RT community to get the real-time stuff working correctly.

I’ll divide the story into a few parts, starting with a quick description of the setup.

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