R2D2 Collects Valentine’s Cards Like A Boss

February 16, 2013 by 14 Comments

r2d2-valentines-card-box

Think back to your school days when each student would make a box which would receive Valentine’s cards from their friends. We have fond memories of buying cards with Teenage Mutant Ninja Turtles on them. We guess this tradition is still going strong. Instead of making a receptacle out of a shoe box  [Dr Franken Storer] helped his seven-year-old build this remote control R2D2 with sounds and lights. Yeah, it’s totally cheating. But who can begrudge a hacker dad a little fun?

The bot started as a desktop trash can. It features a domed top which looks just like the droid, but also has a hinged opening where the cards can be placed. To the lid he attached a tilt switch that triggers a Radio Shack sound player to provide the sounds. These sound modules are popular in a lot of projects like this doorbell hack. The final touch (aside from the droid decor on the outside) was to add a remote control car that lets his son drive R2 around.

We asked for more details and he delivered. You’ll find his lengthy description of the project after the jump.

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Turning An $8 RFID Reader Into Something Useful

February 16, 2013 by 37 Comments

[Fabien] ran across a very, very inexpensive RFID reader on Deal Extreme a while ago and with money to burn, added it to his cart. When the USB RFID reader arrived, he noticed something fairly odd about it (French, Traduction). The RFID reader presented itself to his computer as a USB HID device that spit out characters into a text editor whenever an RFID card was waved above the coil. The only problem was these characters weren’t the hex values recorded on the RFID card. So what’s going on here?

As it turns out (Anglais), this random piece of Chinese electronica sends 10 bytes of data to the computer, just like this well-documented RFID reader. Apparently, both these RFID readers take the hex value of an RFID card, convert those bytes to base 10, and pass each digit through a lookup table. Exactly why it does this is anyone’s guess, but since [Fabien] figured out how it worked, he could also figure out how to reverse the process.

Unfortunately, the RFID reader in question is currently out of stock at Deal Extreme. Seeing as how most of the electronics available there are remarkably similar and differ only in the name printed on the enclosure, though, we wouldn’t be surprised if a nearly identical RFID reader was available elsewhere.

Playing With The Minecraft API And A Raspberry Pi

February 16, 2013 by 8 Comments

mine

It hasn’t been a week since Minecraft for the Raspberry Pi has been released, and already we’re seeing some cool builds that bridge our analog world with Minecraft voxel land. [Martin] got his hands on the Raspi version of Minecraft and decided to take advantage of the API Mojang threw into the build by making a huge analog block clock that keeps real world time in the Minecraft universe.

Basically, [Martin] created a small Python script that draws the face and hands of a clock in a Minecraft world. The Minecraft API comes with neat functions such as drawCircle, and drawLine, so making a real clock face is as simple as getting the system time and doing a bit of trig.

After the break you can check out [Martin]’s Minecraft clock in action. If you’re running the Pi version of Minecraft, you can also get this running on your machine with the code on [Martin]’s git.

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UDP Between STM32-F4 Discovery Boards

February 15, 2013 by 24 Comments

stm32-f4-udp

[The Backwoods Engineer] tested out a new accessory kit for the STM32-F4 Discovery board. The image above shows two boards communicating with the UDP protocol. Notice the extra PCB into which each Discovery board has been plugged. This is a third-party add-on which adds Ethernet, RS-232, SD card slot, and a connector for LCD or Camera. We’ve had one of these F4 Discovery boards on hand for a while and haven’t figured out a good way to connect external hardware to the huge dual pin-headers. This doesn’t solve the problem — the base board also includes dual headers to break-out all the pins — but having Ethernet, serial, and SD certainly reduces the need to add all that much more. The other drawback to the hardware is that the sample firmware is targeted at the IAR Embedded Workbench which is neither free, nor in the realm of affordable for hobbyists.

The NIC used on the baseboard has auto-crossover capabilities so the boards were connected using a regular Cat6 patch cable. This example has the boards constantly sending UDP packets with the module on the right reporting status information to a terminal via the serial connection.

Airsoft Turret Has Turn, Tilt, And Auto-feed To Keep Those BBs Flying

February 15, 2013 by 39 Comments

airsoft-turret-with-laser-cut-parts

Yet another project that proves you need to acquire a laser cutter. This Airsoft turret rotates, tilts, and includes a hopper for ammo.

All of the pieces were cut from acrylic. The base includes a bracket which keeps the large rotating gear level by sandwiching it between the layers. That and the tilt mechanism are pretty straight forward. The module responsible for loading the BBs is pretty neat though. It uses a gear with round teeth the same diameter as the ammo. Once a BB is picked up it is forced upward into the tubing that feeds the gun. Get the full picture from the demo video after the break.

The one thing [The Liquider] is wondering about is how to provide feedback for the tilt and rotate functions. We can’t think of an easier way than to use simple rotary encoders. The Arduino Mega he wishes to use as a driver will have no problem interfacing with reflectance sensors and the acrylic makes it simple to mount this type of black and white encoder wheel.

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Cracking Open A 24-port Switch So You Don’t Have To

February 15, 2013 by 14 Comments

hp-procurve-ethernet-switch-teardown

[Kenneth Finnegan’s] post about this 24-Port HP ProCurve 2824 Ethernet Switch teardown was a delight to read. He’s taking an introduction to networking class at California Polytechnic State University. One of their labs included virtual machines shooting thousands of new MAC addresses at the thing all at once. Despite it’s ability to switch data at a blazing fast rate, it’s ability to deal with that many new hardware identifiers was less than impressive. He wanted to find out why and it just so happened he had one of these in his parts bin at home (which he refers to as if it’s a high-powered RPG character).

The mainboard is divided into three major blocks: the power supply, the switching hardware, and the processor that makes this a manged switch. Although he covers all of these pieces (and the switching stuff is very interesting to learn about) it is the processor section that was causing the aforementioned slowdown. It’s a 266MHz PowerPC chip with a measly 64 MB of RAM. Of course this doesn’t need to be any more powerful since all traffic from previously ‘learned’ MAC addresses gets handled by the switching block and never touches the processor portion.

Don’t miss the end of his post where he discusses how the filtering caps, and semi-isolated ground planes help to tame the beast created from all of this high-speed switching.

Beginner’s Android/Arduino Example Shows The Power Of App Inventor

February 15, 2013 by 20 Comments

This is a simple project. It uses an Android device to switch an LED driven by the Arduino. Connectivity is provided by the Bluetooth module inserted in the breadboard. But one look at the UI on the Android device and you might think this is anything but simple. The truth is that [Kerimil] didn’t spend forever learning Java and programming the app. Instead he’s showing off the power of  App Inventor to get your Android controls up and running fast.

Check out the third button down; when was the last time you added voice commands to your project? It’s worth clicking through to see just how simple that portion was. App Inventor — a Google cast-out that is now maintained by MIT — is a graphical tool that unlocks the power of an Android handset to those with the most basic of programming understanding. For instance, the voice controls shown off after the break are provided by a single bracket which uses conditional statements to ‘listen’ for the words on, off, and blink. You’ll find the voice recognition diagram after the break as well.

You could try to go completely graphical with this project. There’s the option of programming the Arduino side of the project in a similar way.

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