Aleksandar Krstikj.com

Hardware

BarTop Arcade Cabinet running MAME32 (convering analog joysticks to digital d-pads)

by on Jun.12, 2014, under Gaming, Hardware, IT

Well, I finally got around to documenting a project that was started a while back, and has been on hold ever since. I’m talking about my attempt at building myself a Bar-top Arcade Cabinet. The important parts of the project (mainly controls) are done, and the thing functions perfectly. What remains to be done is to build an enclosure and put everything inside so that the thing actually starts looking like an Arcade Machine. Right now, it looks like a transformer that has trouble shape-shifting 🙂

Before you read further on, I suggest you watch the YouTube video I made showing it off. Afterwards, feel free to move on and read how the controls were done, as this is the main custom part of the arcade itself.

Ok, so I take it you watched the video. And I also take it you didn’t listen to my advice of getting digital game-pads and not bothering with analog joysticks. Or maybe, just like me, you had analog joysticks laying around and just want to replicate the same thing I did. Whatever the case, read on.

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Charge Day – The International Holiday Batteries Love

by on Dec.26, 2013, under Hardware, IT

If you’re not confused enough by the title, let me make it worse – I invented my own holiday and it comes every month (or so). I call it “Charge Day” and dedicate it to all electronic devices I have laying around, or more specifically to their batteries. It is a day to spend a little more electricity than usual, and charge all those things which you use every day, or used in the past but don’t really any more.

So why is this holiday important, and why should everyone get behind it? Well the answer is quite literally Life or Death (for your batteries :)). You see, when we get a new electronic device we tend to use it a lot. It’s new, exciting, interesting, and perhaps even useful :). However, as time passes we either get bored of it, upgrade to a newer model, or find it redundant as its functionality just got moved to the newest cell phone on the market. This is where things to downhill.


As we cast that “old” device aside, its battery starts to drain. But, we’re not using it – you might say! And you would be right, but all batteries have a self-discharge rate which varies between battery types, brands, etc. However, they all loose a bit of their power each day, and given enough time – drain completely. Now, it’s all fine and dandy if our battery hasn’t been used for a bit and went from its full charge down to about 80%. Cool, no problem, recharge and go. However, when we don’t use them for a longer period, they may go down to 0, and this is extremely bad. At this point, we’re coming to a state of a battery’s life known as deep discharge, and to keep it simple, batteries don’t like that, and this may and probably will damage them permanently. Keep in mind, this not a state when your cell phone turns off (0%) and you need to recharge, this is well beyond that. At 0% the battery still holds power but it’s just not enough to power your device. Its voltage drops below a certain level and you have to recharge it. However, a state of deep discharge practically means that the battery is completely dead and will probably either not get recharged at all, or won’t hold the charge for very long.
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How to play MP3s in the shower

by on May.26, 2013, under Hardware

If you’re anything like me then you love music! I just can’t go anywhere without something playing some nice tunes in my ears. Whether it’s my home or car stereo, PC, iPad, cell phone, whatever, music follows me everywhere. So obviously, when such a time came that I had to get a new shower cabin I figured, hey, that’s one place I still don’t have music playing.

So I looked around and found a cabin with a built in FM tuner. Of course, there were models which supported playing MP3s straight out of the box but I didn’t feel like throwing money at such a model so I got this one. I should note here that if you’re the type of person who already owns a shower cabin capable of playing MP3s this post may not be for you. But if you’re only able to tune into radio stations this little hint will help you play your custom song selection in the shower in no time.
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M&M Sorter using OpenCV and Arduino

by on May.23, 2013, under Code, Hardware, IT

After my first OpenCV project which dealt with object tracking, I decided to do something a little more challenging and complex, but also more fun. I went for M&M sorting. You might have already seen this idea being realized somewhere online, I know I’ve seen a ton of different examples. However, everyone seems to have a different approach to doing it, so I figured I’ll give it a shot myself.

For those of you that want to jump straight into the action or just want to watch the pretty M&Ms fly about, you can go directly to my video showing the program execution:

If you’re interested in some more details on how the sub-parts of the project function, take a look at this video explaining things a bit better:

Finally, for those of you more into reading, and those looking for the specifics let me present the fine details of the project:
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Tracking a ball and rotating camera with OpenCV and Arduino

by on May.20, 2013, under Code, Hardware, IT

I recently started playing around with the OpenCV library and one of the first tutorials I did dealt with tracking a ball with the camera. I expanded on that concept a bit by having the camera rotate and continue tracking the ball even if it goes off screen. I did this by connecting the camera to a small servo controlled by an Arduino Uno, which receives commands from my PC via a serial connection.


The base project I used can be found here. I decided not to reinvent the wheel and used that code as a starting point so props to the author. However I did modify the code slightly and also added some more things to make it work for my project. The modification refers to changing the color model from RGB to HSV as I found out that it’s much easier to specify a tracking color by using the Hue value rather then finding a good RGB value. The additions refer to the code for serial connectivity and the Arduino instructions send via the serial connection itself.

You can see how the project ended up looking and working in this short YouTube video I made:

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DIY Crossover Cable (with no tools)

by on Aug.08, 2011, under Hardware

What do you do when it’s the middle of the night, you desperately need a crossover cable, and you have no tools apart from a kitchen knife?

…You get creative of course 🙂

(click on the image to expand it)
DIY Crossover Cable

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