Hackaday Links: Sunday, July 21st, 2013


Adafruit tears down a set of brainwave cat ears. They’re made by Necomimi and use your brain waves to adjust a pair of plush cat ears on the headgear.

If your desktop computer is sitting on the floor you may have damaged USB dongles by hitting them with your knees. [Megacier] prevents this from happening again by building a flexible dongle link.

Can anyone help [Brian Benchoff] find a datasheet for this International Rectifier 92-O350 so he can fix up his old VT100 terminal?

Here’s a quick example of how to graph data from a Raspberry Pi on the sen.se cloud service.

Have some extra fun with your oscilloscope by displaying any image. This set of conversions starts with a picture and ends with an audio file that will draw it on the scope’s screen.

You’ve probably already heard that the Sikorsky Prize for human powered helicopter has been claimed. If you didn’t see any footage of the flight now’s your chance. [Thanks Adam]

Hardware store goods and an mbed combine help solar panels track the sun


If you have the space, and can build a tracking rig cheaply you’ll be able to get a lot more out of your solar panels. That’s because they work best when the sun’s rays are hitting them perpendicular to the surface and not at an angle. [Michael Davis] hit both of those stipulations with this mbed powered solar tracker.

At a garage sale he picked up an antenna motor for just $15. The thing was very old, but still wrapped in the original plastic. It’s beefy enough to move his panels, but he first needed a way to mount everything. After checking his angles he built a base out of wood and used galvanized water pipe as an axle. Cable clamps mate his aluminum angle bracket frame to the pipe. This frame holds the panels securely.

To track the sun he used two smaller cells which aren’t easy to pick out in this image. They are monitored by the mbed microcontroller which measures their output in order to point the assembly in the direction which has the most intense light. A couple of limit switches are included to stop the assembly when it reaches either side.

This technique of using small solar cells as the tracking sensors seems to work well. Here’s another project that took that approach.

[Read more...]

How the mazes were generated for classic Berzerk game


This is a screenshot from the Atari 5200 version of the classic game Berserk. But the write-up we’re featuring actually looks at the original coin-op version. The maze for each level was established on the fly using a seed number fed into a rudimentary algorithm . Here’s a close look at how the maze building code actually worked.

Recently we saw a talk by Pitfall creator [David Crane] as part of our Retrotechtacular series. That is a real gem of programming history, and one of our favorite take-aways was that the levels were not hardcoded, but built using a random number generator algorithm with a hardcoded seed (so that the game was the same each time you played it). This uses a similar method but with a somewhat random seed.

The maze building was reverse engineered by observing the game in a MAME emulator, and by digging through disassembled code. Each time the code is “cold started” the seed starts out at zero, but from there the room number is used as the next seed. This is fed through a very simple algorithm. It generates directions for the walls, which use s few bit-wise operations to add the pillars inside the rooms.

It’s a great thing to study if you’re writing games for your embedded projects. By generating the room programmatically you don’t use up as much program memory. Of course these days even simple hobby controllers have way more storage to work with than [Alan McNeil] had when he designed Berserk.

[via Reddit]

[Image Source]

Quadruple backflip and sticks the landing


This must have been a coding nightmare, and let’s not even mention the particulars of the mechanical build. The blurred ball near the center of this image is a robot doing a quadruple backflip before sticking the landing.

To the right is a high bar supported by a wood column and some guy-wires. At the beginning of the video below [Hinamitetu] hangs the robot from the bar where it starts its performance without any real motion. The servo motors whine as it gets ready; quickly getting up to speed with full revolutions around the bar. Oh how we wish there was more background info on the hardware! But we’re perfectly happy making our way through [Hinamitetu's] video collection, which include other gymnastics disciplines like the floor routine. He even posted his own blooper reel that shows the high bar isn’t always a rosy experience.

If you’re thirsting for more amazing performances you won’t be disappointed by this high wire act.

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