Year: 2012

Mesh Networking With Multiple Raspberry Pi Boards

November 14, 2012 by 19 Comments

Since he’s got several Raspberry Pi boards on hand [Eric Erfanian] decided to see what he could pull off using the robust networking tools present in every Linux installation. His four-part series takes you from loading an image on the SD cards to building a mesh network from RPi boards and WiFi dongles. He didn’t include a list of links to each article in his post. If you’re interested in all four parts we’ve listed them after the break.

He says that getting the mesh network up and running is easiest if none of the boards are using an Ethernet connection. He used the Babel package to handle the adhoc routing since no device is really in charge of the network. Each of the boards has a unique IP manually assigned to it before joining. All of this work is done in part 3 of the guide. The link above takes you to part 4 in which [Eric] adds an Internet bridge using one of the RPi boards which shares the connection with the rest of the mesh network.

If the power of this type of networking is of interest you should check out this home automation system that takes advantage of it.

Continue reading “Mesh Networking With Multiple Raspberry Pi Boards” →

Put Your Dev Board To Work As A Demoscene Display

November 14, 2012 by 4 Comments

If you’re looking for a way to push your comfort zone with that slick new microcontroller you’ve been working with we think [Morgan Gangwere] has the answer. He took his chipKit development board and used it as a demoscene platform.

Demoscene refers to audio and visual demos written to squeeze as much entertainment out of a given platform as possible. We’ve seen demos for a lot of different platforms; for instance, here’s a Propeller chip demo. But this use of the onboard OLED screen brings a smile to our faces. With well under 100 lines of code [Morgan] implemented several different video effects (the music heard in the clip after the break is not being produced by the board). There is a star field which serves as the background. Over the top of it a scrolling message is displayed following a sine wave shape. The speed at which it scrolls is set by the trimpot, which you can see adjusted about 50 seconds into the clip.

Continue reading “Put Your Dev Board To Work As A Demoscene Display” →

Wristband RFID Unlocks Car Door And Starts Engine

November 14, 2012 by 19 Comments

[João Ribeiro] is an electronics engineer by day, but in his free time he likes to ply his trade on everyday items. Recently he’s been integrating his own microcontroller network to unlock and start his car via RFID. In addition to the joy of pulling apart the car’s interior, he spent time designing his own uC breakout board and developing an RFID reader from a single chip.

He’s working with a 1988 Mercedes that has very little in the way of electronics. It sounds like the stock vehicle didn’t even include a CAN bus so the prelude to the RFID hack had him installing a CAN bus network made up of two microcontrollers. One reads the velocity and RPM while the other displays it on the tachometer. When he began the tag-based entry system he used an RFID reader module for prototyping, but eventually built his own reader around the TRF7960 chip. This included etching his own receiver coil which was mounted in the side-view mirror bracket. To unlock the doors he holds the bracelet up to the mirror and the vehicle lets him in. The video after the break starts with a demonstration of the completed project and moves on to some build videos.

We certainly like the idea of using a bracelet rather than implanting the tag in the meaty part of your hand.

Continue reading “Wristband RFID Unlocks Car Door And Starts Engine” →

Playing Led Zeppelin On A C64

November 14, 2012 by 24 Comments

[youtube=http://www.youtube.com/watch?v=Iikj5EfL770&w=470]

In the C64 demoscene there are a ton of awesome software hacks that push the Commodore 64, the 1MHz 6510-based computer from 1982, to its limits. Most of these C64 demos are very much limited by the hardware inside the C64, but the demoscene is always coming up with new ways of pushing the envelope. [No Quarter] just sent in one of these software hacks that propel the capabilities of the C64 into the realm of absurdity by playing full length songs directly from the floppy drive.

Playing a song on the C64 begins with an Amiga and a Perfect Sound digitizer to convert the digital audio file into a 4-bit sample. Once this sample is transferred over to the C64 where it was manually timed so streaming it off a 1581 disk drive would result in the song playing at the correct pitch. It’s an amazing work of optimization; the audio data is streamed off the disk just as fast as it’s played from memory, an amazing data throughput rate for the ‘ol C64

After the break you can see [No Quarter] playing Led Zeppelin, Bon Jovi, Shania Twain, and Extreme. A very, very cool project and with the addition of a C64 hard drive makes it possible to have a media player for the C64.
Continue reading “Playing Led Zeppelin On A C64” →

Make Dual Pin Header Footprints Into Breadboard Friendly DIP

November 13, 2012 by 28 Comments

[John] wrote in with a solution to a prototyping issue that has vexed us for quite some time. Above you can see the DIP friendly solution for dual-row pin headers which he came up with. With just a bit of easy soldering he now has a breadboard friendly device for prototyping.

He starts by soldering a dual row pin header on the board, then clips off all of the legs on the outside row. The row of legs that remain are then inserted into one side of the trench on his breadboard. The other side of the trench has a single row pin header, and he solders them to the outer row on the breakout board using another single pin header aligned horizontally. This isn’t a 100% convenient solution, as it’s still pretty hard to get your jumper wires in the breadboard on the side covered by the breakout board. But if you plan in advance you can place your wires first, then plug in the development board.

Here [John] is working with TI’s eZ430-RF2500 board. We’d like to go back and remove the dual pin socket we soldered on our eZ430-F2013, replacing it with this style of pins.

A Nostalgic Look At What A 13 Year Old Can Do With A C64

November 13, 2012 by 41 Comments

[Armin] recently pulled out his Commodore 64 and looked back on the projects he did as a kid. The surprising thing is that we’re not talking quite as far in the past as you might image. He was 13 in 2002 and the family didn’t have a PC. But more than a decade before his father had purchased a C64 and [Armin] dug into the manual to teach himself how to code. This week he connected the old hardware to his video capture card to give us a demonstration on what he accomplished.

He had seen Windows 95 at the local computer club and figured why not program a clone of the software for the machine at hand? He called it Windows 105 (because that number is higher than 95) and worked out ways to mimic programs like DOS, Corel Draw, Notepad, and some of the programs from Microsoft Office. They didn’t include all the functionality of the real thing, but the look was there.

The story does have a happy ending. [Armin’s] parents saw what he was doing and managed to pick up a PC for him to play with. Now he’s a professional programmer looking back on the formative years that got him there. We’ve embedded one of his demo videos after the break for your enjoyment.

Continue reading “A Nostalgic Look At What A 13 Year Old Can Do With A C64” →

7400 Logic Competition Winners Announced

November 13, 2012 by 12 Comments

The 7400 Logic Competition has drawn to a close. The winners were announced and there are quite a few of them. There were fifteen first place winners named, nine second place, and nineteen third place projects. The bounty of quality entries is a testament to the popularity of the contest. It helps to have a wide range of prizes and the post linked above lists all of the sponsors who donated goodies as an incentive.

The board seen above was awarded the reader’s choice, to which the grand prize was awarded. It is a 7400 series calculator. [Umair Mukati] and [Naveed Ahmed] — both are students at the Institute of Industrial Electronics Engineering in Karachi, Pakistan — developed the device as part of a class project. It is capable of adding or subtracting two digit numbers. This includes support for negative numbers as results. We’ve embedded a video demo of the calculator in action after the break.

Continue reading “7400 Logic Competition Winners Announced” →