Guide For Working With AVR Microcontrollers

March 14, 2011 by Mike Szczys 8 Comments

[Q] wrote in to let us know about the AVR-Guide he’s been working on. It looks like he’s finished posting about 80% of the content he planned for in his initial draft outline. We read through several of the sections and found them to be concise, yet able to present information in a way that’s easy to grasp. The screenshot above shows the most basic block of information to get started with AVR microcontrollers. We’ve covered the same information in our AVR tutorial series and think that reading through both will give you a strong understanding of the knowledge needed to work with 8-bit microcontrollers with confidence. But this resource doesn’t stop after the basics. If you’re looking to bolster your knowledge of all the features the AVR line has to offer there’s also sections explaining Digital I/O, Interrupts, Timers, Analog I/O, Communications, and Miscellaneous topics.

The site is called QEEWiki. We logged in using a Google account (this is hosted as a Google site) but didn’t see a way to edit the information. If this truly is a Wiki and you know how to edit pages please leave a comment about it after the break.

Beginner Concepts: 595 Shift Register Simulator

March 14, 2011 by Mike Szczys 7 Comments

[Aaron] just finished building an online 595 shift register simulator. These inexpensive chips let you extend the number of devices that can be controlled by a single microcontroller. You see them in quite a few LED multiplexing projects, included the Ping Pong Clock that we recently built. But they can be a bit tricky to fully grasp if you’re not familiar with the hardware.

This simulator gives you a point-and-click interface for the five possible control lines on a 595 shift register. There are three pins that must be manipulated to use the device; the serial in, clock, and latch pins. The other two are for clearing the register, and enabling output and can be considered optional. You can choose to control these with a microcontroller in your own projects for more flexibility, but often they are tied to either VCC or GND (depending on the chip) when these features are unnecessary. Give this simulator a try and then take what you learned over to a solderless breadboard and see if you can write some firmware to produce the same results. If you’re still having trouble you can take a look at this 595 tutorial for further information.

Commandeering Public Video Screens: Real Or Fake?

March 14, 2011 by Mike Szczys 66 Comments

It’s time for everyone’s favorite comment thread game: Real or Fake? This week’s edition comes in from a tip that [Phil] sent about a way to take over video screens in Times Square. Watch the video after the break to see the hackers using a two-part solution to rebroadcast video from an iPhone onto a screen in the busy urban setting. The first part is a transmitter that plugs into the iPhone, the second is a signal repeater that, when held close to a video screen, overrides the clip currently being displayed with the video from the handheld. The image above shows the repeater being floated up to the big screen using a giant red balloon which you can make out in the black bar to the left of the replayed video.

Our first thought is that someone just watched Tron: Legacy and wanted to have a little Sci-Fi fun with the Internets. We can’t imagine a hardware solution that would actually make this work, but please do share your thoughts about that in the comments. We’d suspect this is more of a video hack that uses After Effects, similar to how the stopped motion candle video of the eyelid shutter glasses videos were faked. But apparently there is a follow-up video on the way that will show how the prototype was made so we could be wrong.

update: [Phil Burgess] points out that the “repeater” looks awfully familiar.

Fake for a variety of already-stated reasons (e.g. video out the headphone jack?). But the smoking gun, watching the 720P video on YouTube, is that I plainly recognize the hardware they’re using as the “repeater”: it’s simply the internals from a Digipower JS1-V3 cell phone USB boost charger (having torn apart a few myself):

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Frequency Counter For $10 Worth Of Parts

March 14, 2011 by Mike Szczys 10 Comments

[Scott] built this frequency counter using less than $10 in parts. It’s set up to meter frequencies in megahertz which is fitting since he’s planning to use it with his radio hardware experimentation. But we would find it useful too because our cheap multimeter only reads up to around 4 MHz.

He’s using an ATmega16 that he had on hand but it has features way beyond the specs for the device. He speculates that an ATtiny2313 would easily work in its place. The microcontroller is mostly used to drive the multiplexed 7-segment display after reading the frequency values from the 74LV8154 counter chip that he is using. He doesn’t have a full schematic for the device, but there is a hand drawn diagram for using the frequency counter; the rest should be easy to piece together. Looking at that circuit we don’t think it would be too hard to make this a manual-ranging frequency counter to give you more use out of the dedicated device. Check out [Scott’s] demonstration video which is embedded below the fold.

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Protei: Articulated, Backward Sailing Robots Clean Oil Spills

March 12, 2011 by Mike Szczys 15 Comments

The Protei project aims to develop a robotic solution for oil-spill cleanup. [Cesar Harada] quit what he calls his dream job at MIT to work toward a solution to the ecological disasters that are oil spills. He had previously been working on Seaswarm, a swarm of robots that use conveyor belts of absorbent material to leech oil from seawater. But Protei doesn’t use legions of drones. It aims to use better design to improve the effectiveness of a small number of units.

The whole idea is well described in the video after the break. If a long trailing boom of absorbent material is towed in a serpentine pattern perpendicular to the flow, starting down current and moving upward, it can be quite effective at halting the spread of crude. Initial experiments have shown that a robotic vessel can do this efficiently with just a few improvements. First, to counteract the drag of the tail the rudder of the boat was moved to the bow. Secondly, the hull has been articulated as you can see above. This allows the robot to better utilize wind power to sail, making turns without losing the push of the wind.

The project is raising money through Kickstart as an open hardware project. Let’s hope this becomes a cheap and effective way to fix our costly drilling mishaps. Continue reading “Protei: Articulated, Backward Sailing Robots Clean Oil Spills” →

NBA Hangtime Pinball Display

March 12, 2011 by Mike Szczys 1 Comment

[Ed Zarick] continues work on his NBA Hangtime pinball machine with the completion of the scoreboard and backglass. You should remember this project as we already covered the layer audio he developed for the system. Now he’s proving to be a protoboard master, using point-to-point techniques to build a pair of two and a half digit LED displays for team scores, as well as a shot clock timer and other status indicators.

The lighting board that controls it all is commanded via the i2c protocol, just like the three audio modules. It uses shift registers along with MOSFETs and [Ed] has taken the time to add pin headers and sockets for board interconnects. As is true with the audio system, one Arduino Mega acts as the master on the i2c bus and you’ll notice in the video after the break that the display works in perfect harmony with the sound effects.

We can’t wait to see what he comes up with for the play field!

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Building Your Internet Radio Empire

March 12, 2011 by Mike Szczys 19 Comments

It all starts with one station in your home office but who knows where it can go from there? If you’ve got dreams of being an Internet radio jockey you can get some ideas about equipment startup from this setup that [Viktor’s] built for a friend.

He started out with a plan to have a station that offers twenty-four hour streaming but also supports live broadcast. Two computers are used in the setup. The first handles automated music broadcast and live mixing. This box has two sound cards, one is used for the automated music by feeding the output into a sound mixer that is a separate piece of hardware. The output of that mixer feeds back into the second sound card on the box. This secondary card outputs the final mix to the computer speakers.

The second computer is where a lot of the live broadcast work is done. Any steaming guest (using VOIP or Skype, etc.) come in through this box as well as jingles and sound effects used during the feed. Its sound card is also connected through the external mixer and joins the final feed headed into one of the sound cards on the primary computer.

In the end the Internet connection for the system isn’t beefy enough to reliably support a streaming station. For this a dedicated streaming service is used. It receives the live feed and then uses its increase bandwidth to propagate the signal to listeners anywhere in the world.

Want to listen to this radio station? Build your own streaming radio module, or outfit classic hardware to work with your computer.