Using Arduino Shields With The Raspi

October 10, 2012 by 12 Comments

With hundreds of Arduino shields available for any imaginable application, it’s a shame they can’t be used with the Raspberry Pi. Breaking out the Raspi GPIO pins to Arduino-compatible headers would allow makers and tinkerers to reuse their shields with a far more capable computing platform.

The folks over at Cooking Hacks realized a Raspi to Arduino shield bridge would be an awesome device, so they made their own, complete with a software library that allows you to port your Arduino code directly to the Raspberry Pi.

There are a few limitations with the Raspberry Pi’s GPIO headers; the Raspi doesn’t have analog inputs, so the Cooking Hacks team added an 8-channel ADC. Along with analog inputs and the headers required to pop a shield on the board, there’s also a socket for an XBee module.

The software library contains most of the general Arduino functions such as digitalWrite() and digitalRead(). There Serial, Wire, and SPI libraries are also implemented, allowing any device that communicates through UART, I2C, or SPI to talk directly to the Raspberry Pi.

While the Raspi Arduino bridge doesn’t allow for PWM in the same capacity as an Arduino, you’re always welcome to whip up a servo or LED shield for this neat little adapter.

Free Software Foundation Certifies Hardware That Respects Your Freedom

October 10, 2012 by 32 Comments

The Free Sofware Foundation, the very same organization responsible for the GNU General Public License and open source advocacy on the part of the Free Software stalwart [Richard Stallman], has certified its first piece of hardware as Respecting Your Freedom.

This new certification goes far beyond the goals of Open Source Hardware. In addition to providing documentation, schematics, and design files, hardware certified as Respecting Your Freedom must meet much more stringent requirements.

Of course, all software used with RYF hardware must be Free Software, but the certification also carries with it a few more requirements. The source and CAD files must be provided, it must use formats unencumbered by closed licenses, and the hardware must not spy on the user.

The honor of the first RYF-certified piece of hardware goes to, of course, a 3D printer. It’s the AO-100 printer developed and sold by Aleph Objects, Inc., a.k.a. Lulzbot out of Colorado.

With so many Open Source Hardware projects coming down the pipe, it’s great to see a somewhat more militant organization (that’s a good thing!) such as the Free Software Foundation provide a certification process for hardware projects. Keep in mind this isn’t a ‘certified once and forget about it’ proposition; the FSF is willing to provide a bounty to encourage the public to report violations of RYF certification. Anything to keep them honest, right?

Playing Around With MRAM

October 10, 2012 by 26 Comments

For the longest time, hardware tinkerers have only been able to play around with two types of memory. RAM, including Static RAM and Dynamic RAM, can be exceedingly fast but is volatile and loses its data when power is removed. Non-volatile memory such as EPROMS, EEPROMS, and Flash memory retains its state after power is removed, but these formats are somewhat slower.

There have always been competing technologies that sought to combine the best traits of these types of memory, but not often have they been available to hobbyists. [Majenko] got his hands on a few MRAM chips – Magneto-Resistive RAM – and decided to see what they could do.

Magneto-Resistive RAM uses tiny pairs of magnetic plates to read and write 1s and 0s. [Majenko] received a sample of four MRAM chips with an SPI bus (it might be this chip, 4 Megabits for $20, although smaller capacity chips are available for about $6). After wiring these chips up on a home-made breakout board, [Majenko] had 16 Megabits of non-volatile memory that was able to run at 40 MHz.

The result was exactly what the datasheet said: very fast write and read times, with the ability to remove power. Unlike EEPROMS that can be destroyed by repeated reading and writing, MRAM has an unlimited number of write cycles.

While MRAM may be a very young technology right now, it’s a wonderful portent of things to come. In 20 (or 30, or 40) years, it’s doubtful any computer from the largest server to the smallest microcontroller will have the artificial separation between disk space and memory. The fact that any hardware hacker is able to play around with this technology today is somewhat amazing, and we look forward to more builds using MRAM in the future.

100,000 Lumen Chandelier Is Like Having The Sun A Few Feet Above Your Head

October 10, 2012 by 45 Comments

[Michail] doesn’t mess around when it comes to lighting. He built this 100,000 Lumen chandelier to make sure his office is bright during the dreary months. The thought is that it will provide the health benefits of long sunny day. It has been hanging for about a year now, and he slowly came to the realization that it’s several times too bright for indoor use.

We know where he’s coming from though. When it’s dark at 5 pm we want it to be plenty bright inside. He started with an incandescent bulb, then moved through compact fluorescent and halogen bulbs before deciding to undertake the build. What you see above are 150W Metal Halide lamps.  There is some danger to using these without an enclosure. They do emit some UV light and they can explode. So whenever you buy a fixture that uses them there’s a sheet of filtering safety glass sealing up the enclosed sockets. [Michail] decided not to bother with this safety feature, instead depending on the benefits of an electronic ballast. He says these reduce the chances of an explosion sending scorching hot glass shrapnel your way.

As we mentioned earlier, his conclusion is that just one of these bulbs is enough to illuminate his small office.

New Hackaday Template Coming Soon. Here’s Your Chance To Make It Better!

October 9, 2012 by 339 Comments

<edit — Dark default layout (now shown above) with white option>

We’re going to be implementing a new template soon. We’ve been wanting to do this for years and it is finally happening. There are many reasons why this is necessary from site load speed to better commenting. This will give use more control over what is in our sidebar (right now I have to hand code everything into the friggin’ template!).

This is going to happen.  Help us make it awesome.

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Oscilloscope VFD Repair Like Doing Brain Surgery On Yourself

October 9, 2012 by 11 Comments

[Jerry Pommer] has an old Tektronix 2236 that is having some issues. Just to the right of the top corner of the screen is a VFD display that is used to show various numerical measurements. Unfortunately this has stopped working, so he made the oscilloscope probe itself in order to trouble-shoot the situation.

The entire repair process was filmed and you can see the 42-minute job embedded after the break. There’s a lot of stuff crammed inside that oscilloscope, and we see a tour of it all at the beginning of the video. Once [Jerry] gets down to business he traces the problem to a JK Flip-Flop used to feed the display. The output appears correct at first, but the clock signal is not functioning as expected. His solution is to use an MSP430 chip to replace the Flip-Flop functions.

The confidence to try this repair was sparked by [Todd Harrington’s] car-stereo VFD repair video.

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Gravity Bike

October 9, 2012 by 73 Comments

This bicycle has no pedals and really nothing that resembles a seat. It’s not so much a way to get around as it’s a way to get down. Down from the mountain, and down low to the pavement. This is a gravity bike built by the guys at S.I.N. Cycles.

The frame is a long triangle which stretches the wheel base to make room for the rider. After getting the layout just right and welding the frame together they added the rather unorthodox building step of pouring molten lead into the hollow frame tube. This bike is used to descend a mountain road with the force of gravity, so the extra weight will help pull it just a bit faster. There’s one thing you’ll want to make sure is working before you climb aboard — the single front brake which you’ll need when coming into the curves. Check out some ride footage on this thing in the video after the break.

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