Multitouch Tower Defense Uses Physical Towers

August 31, 2011 by Mike Szczys 4 Comments

If you’re tired of playing flash games with a mouse, perhaps you’ll draw inspiration from this project. Arthur built a multitouch interface that uses objects as part of the control scheme. In the image above you can see that the game board for a tower defense game is shown on the display. There is a frustum-shaped game piece resting on the surface. Just place that piece where you want to build your next tower, and then select the tower type from the list.

The controller itself is pretty straight-forward. The surface is a piece of acrylic topped with some light diffusing material. A projector shines through another acrylic window on the side of the unit, reflecting on a mirror positioned at a 45 degree angle. As for the multitouch detection, the hardware uses a series of UV LEDs along with a modified PS3 eye camera. [Arthur] chose the reacTIVision software package to process the input from the camera. Check out a couple of videos after the break to see the hardware, and some game play.

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Virtual Machine For Microcontrollers Lets You Run Python On AVR Chips

August 31, 2011 by Mike Szczys 23 Comments

[Clifford Wolf] wrote in to let us know about a project he recently completed called EmbedVM. It’s a virtual machine for AVR microcontrollers. The package has a relatively small overhead, taking up about 3kB of program memory. The VM can execute 74,000 instructions per second, and runs asynchronously from the microcontroller. As [Clifford] demonstrates in the videos after the break, this can be handy for preloading commands to prevent slowdown during heavy VM processor loads.

The snippet in the image above is an example program written in the C-like VM code which will play some [Rick Astley] on a speaker. This code can be run from RAM, EEPROM, or even external storage like an SD card. Recently there was a supplemental compiler project that even takes Python code and compiles it into VM byte-code. What a nice abstraction tool for making inexpensive microcontroller-based designs easily programmable for those that have a bit of Python experience.

If you don’t recognize the name, [Clifford Wolf] is also the author of OpenSCAD, a tool that is quite popular with 3D printing.

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The Life And Death Of A Fantastically Brilliant Flashlight

August 31, 2011 by Mike Szczys 21 Comments

[Holzleim’s] flashlight build is quite impressive. And the rise and fall of the hardware is quite a story. He designed it as a handheld light, relying on batteries to power a multitude of high-power LEDs inside.From the collection of four 5350 mAh lithium polymer cells he was able to achieve a peak power output that surpasses 500 Watts!

Projects that make use of these powerful LED modules have heat dissipation as a major design element. With this in mind, [Holzleim] used large bars of copper as a mounting surface for each group of modules. The size and thickness of these bars made it difficult to use traditional soldering techniques to affix the bodies of the modules so he ended up using a clothes iron to ramp up the temperature high enough to reflow the solder. Once mounted, most of the LEDs were paired with optics, including that Fresnel lens at the center, to help focus the light.

To keep the batteries topped off, [Holzleim] designed his own external charger which can run off of mains or from a car’s electrical system. Unfortunately he must not have included a way to monitor the battery temperature because one of the cells failed, causing a fire that burnt out the components inside the flashlight. Luckily his wife was home at the time and got the failing device outside where it didn’t cause more damage. We’ve linked to his posts regarding the charging system, the properly functioning light burning paper with its beam intensity, and his sad announcement about the fire after the break.

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Making A Line-following Toy Into A Programmable Robot

August 31, 2011 by Mike Szczys 1 Comment

[Eric Gregori] picked up this little yellow robot as a kit build. It has a single PCB inside that has a pair of IR emitters and detectors pointed downward at the front of the robot. It is able to follow a dark line on a light surface based on how the infrared beam reflects back to the detector. But it’s a one-trick pony that [Eric] wanted to make into a programmable robot.

The kit came with a schematic, which makes the process of patching into its logic quite easy. There are two motors, each with a driver circuit made up of a pair of transistors and one flyback diode. This means the motors can only move in one direction, but they also only take one logic connection to control. Instead of populating the transistor that usually connects the IR receiver to the motor driver, [Eric] soldered jumper wires from each to an MSP430 chip (the G2231 that came with his Launchpad).

As you can see in the clip after the break, the first version of the code he wrote makes the robot follow a line as it would if it had not been altered. But there’s still plenty of programming space and several free I/O pins for future improvements.

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Dustbin Computer Lets You Clean And Prototype With A Neato XV-11

August 30, 2011 by Mike Szczys 8 Comments

So you bought yourself a Neato XV-11 and your floors have never been cleaner. The only problem is that you want to hack around with the hardware without losing your floor-sweeping minion. [Hash] found a solution to the issue by building a computer inside of the dustbin module.

You can see at the center of the image above a touchscreen. Normally this is just blank plastic, as it’s the removable container where your floor sweepings go, but [Hash] was inspired by the modular design. Since that bin is intended to be removable, it’s a perfect way to make add-on hardware removable. All he needed to do was find a way to connect to the Neato’s own electronics. The solution was a non-standard USB cable.

Using the guts from an Insignia Infocast 3.5 (he picked several of them up on clearance at Christmas) he milled an opening for the touch screen, added a cooling fan, and wired up a toggle switch (not pictured above) which powers everything from the 14-17V coming in from that USB cable. The Infocast is a Chumby with a different branding so there’s plenty of Linux-based power and it’s WiFi enabled. Watch [Hash’s] walk through video after the break to see all that went into this clever concept.

We haven’t seen too many hacks that make use of the Neato XV-11. [Hash] is the same guy who hacked the Lidar on the unit, but there must be others turning out impressive projects. Don’t hesitate to send in a tip if you know of one.

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A Cellphone Based Interactive Voice Response System

August 30, 2011 by Mike Szczys 8 Comments

We’re all familiar with IVRS systems that let you access information using a touch-tone telephone. [Achu Wilso] built his own version which uses a cellphone, microcontroller, and computer.

The cellphone is monitored by an LM324 op-amp with an attached 555 timer chip. When a call comes in the voltage on the headphone output goes high, activating the timer circuit. If it goes low and does not go high again for about 25 seconds the call will be ended. Each incoming touch tone acts as a keepalive for the circuit.

An MT8870 DTMF (touch tone) decoder chip monitors the user input. An ATmega8 microcontroller grabs the decoded touch tones from that chip, and pushes them to a PC via USB. The PC-side software is written in Python, using MySQL bindings to access database information. eSpeak, the open source speech synthesizer software is used to read menu and database information back to the caller.

Not a bad little system, we wish there was an audio clip so we could hear it in action.

Retractable IPad Dock For The Kitchen

August 30, 2011 by Mike Szczys 17 Comments

[Evan Flint] and his wife use a lot of online recipes in the kitchen. Rather than printing them out, they bought an iPad as a cooking companion. But in their cramped kitchen he needed to find a place for the high-end hardware that is out-of-the-way yet accessible. Some head scratching and parts bin diving led to this under-cabinet iPod dock.

The dock itself is a cradle made out of sheet aluminum. After cutting to shape, [Evan] bent up the sides and bottom to center the iPad. Since this is not a permanent fixture he needed to make the cradle collapsible. He used a CAD program to design the base tray to let the cradle lay flat, while giving several options to the angle when it is in use. Once the cooking is done just fold it up and the drawer slides make for easy under-cabinet storage.

Because he doesn’t own the house he didn’t want to make permanent alterations to the cabinet. But he does lament the unfinished look of the drawer slides. We’d just grab some pre-finished oak crown molding from the home store and wrap the entire thing. The left-edge of molding could slide out with the cradle when in use.