Programmable Scientific Calculator Watch

January 19, 2009 by Nick Caiello 17 Comments

When the band support on [David]’s Casio CFX-400 Scientific Calculator Watch finally broke after 10 years of use, he found it almost impossible to find another watch with the same functionality. Like any good engineer, [David] decided to design a watch to meet his needs. The result of his endeavors was the µWatch, a programmable watch based on a PIC24 with both RPN and Algebraic calculation modes. The watch runs open source software and is expandable thanks to a serial port, an ICSP programming port, and a spot for an infrared LED on the board. On his site, [David] shows how he made the first µWatch and offers kits for anyone who wants to build their own. We’ve been told that the next batch of kits will be made available in 1-2 weeks and are expected to sell out fast.

[Thanks Tomesz]

Servo Switch Assemblies

January 19, 2009 by Caleb Kraft 16 Comments

[youtube=http://www.youtube.com/watch?v=P0hBCdMJ96g]

If you are interested in trying out some home automation, but don’t want to get into the potentially dangerous area of hacking your house wiring, consider these servo switches. These allow you to flip a switch, using a servo. They are clean, temporary, and fairly compact. You can purchase them at oomlout.com or download the designs and build your own.

High Frequency Start Box

January 19, 2009 by Caleb Kraft 52 Comments

start_box

When welding with an AC arc welder, it is often necessary to “scratch start” them to get the arc going. For those unfamiliar, it is just like it sounds. You drag the head across something just like a giant match. There are some that come with an arc stabilizer or “high frequency starter”. This is preferred, but they can be hard to find. [Bill] shows us how to make one of our own. Though you may have an easy enough time finding a big transformer, you might run into some difficulty finding the capacitors, and tungsten spark gaps. If you manage to get your hands on them, you can follow [Bill]’s schematic and build one of these starters for yourself.

Quick Cheap Remote Outlets

January 19, 2009 by Caleb Kraft 16 Comments

ir_plugs1

[jwad650] wanted a remote controlled power strip. These are fairly expensive, with a single outlet running roughly $15. He was able to build a 6 outlet version for about $50. He is using an SIS-7c to decode signals from a universal remote. Each plug is individually controlled by a 3Amp relay. Be careful making this, there’s lots of nasty shock potential in that mess of wires. We recommend that you confine it in an enclosure as well. [jwad650] plans on adding an enclosure, as well as LED indicators and fuses. You can see a video of it in action after the break. If you want more information about working with relays, check out the working with relays writeup.

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Multitouch Tabletop Gaming

January 18, 2009 by Eliot 29 Comments

[youtube=http://www.youtube.com/watch?v=QflrIK-m4Ts]

Reader [Ramon Viladomat] sent in what he has been working on over the last year at the Universitat Pompeu Fabra in Barcelona. Tired of see nothing but zooming map demos, he created a roleplaying game that takes advantage of the reacTable‘s multitouch interface. Along with multitouch, the reacTable also uses tangible fiducial markers to represent objects and as an alternative input method. Embedded above is a video demoing the interface and gameplay (starts at 3:43). The game lets you move your miniature through a virtual world. The surface shows you how far you can move dynamically as your action points regenerate and slowly reveals more dungeon as you discover it. You can pause the action and use gestures to set attack patterns. We really like this demo and would love to see someone build one using a popular tabletop game like Warhammer 40K. Embedded below is a demo of the associated map editor.

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Use The CPU Cache To Prevent Cold Boot? No.

January 18, 2009 by Eliot 21 Comments

coldboot

Frozen Cache is a blog dedicated to a novel way to prevent cold boot attacks. Last year the cold boot team demonstrated that they could extract encryption keys from a machine’s RAM by placing it in another system (or the same machine by doing a quick reboot). Frozen Cache aims to prevent this by storing the encryption key in the CPU’s cache. It copies the key out of RAM into the CPU’s registers and then zeroes it in RAM. It then freezes the cache and attempts to write the key back to RAM. The key is pushed into the cache, but isn’t written back to RAM.

The first major issue with this is the performance hit. You end up kneecapping the processor when you freeze the cache and the author suggests that you’d only do this when the screen is locked. We asked cold boot team member [Jacob Appelbaum] what he thought of the approach. He pointed out that the current cold boot attack reconstructs the key from the full keyschedule, which according to the Frozen Cache blog, still remains in RAM. They aren’t grabbing the specific key bits, but recreating it from all this redundant information in memory. At best, Frozen Cache is attempting to build a ‘ghetto crypto co-processor’.

We stand by our initial response to the cold boot attacks: It’s going to take a fundamental redesign of RAM before this is solved.

[via Slashdot]

ATtiny Breadboard Headers

January 18, 2009 by Eliot 22 Comments

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[Alex] was frustrated by the amount of time it took to start prototyping with an AVR ATtiny. To make things easier, he built headers that carry the 8 and 20 pin chips and plug directly into breadboards. The boards include a 6pin ISP header, resonator, pull-up resistor, reset, and blocking caps. The ATtiny2313 version also has a serial connection header. This is a prototype though, and he forgot to route one of the connections. He plans on having a large batch of boards ready for next month.