Raspberry Pi Used As A Beacon Transmitter

January 25, 2013 by Mike Szczys 14 Comments

[m0xpd] got his hands on an inexpensive AD9850 DDS Module from eBay but needed a way to control it. He took inspiration from the projects that used a PIC microcontroller, but decided to add his own twist by using a Raspberry Pi to build a multi-mode beacon transmitter.

At the center of this breadboarded circuit lies the green AD9850 module. To its left is a level converter he built to get the 3.3V levels from the RPi board to work with the rest of the 5V hardware. The signal then feeds into a QRP amplifier and a low pass filter.

He didn’t start from square one when it came time to write the code for the RPi. Instead he grabbed an Arduino sketch for the very same DDS and ported it over to Python. The first test signal was his call sign sent in Morse code at QRSS speeds. But he also managed to get Hellschreiber messages working, making it a multiple-mode device.

[via Solder Smoke]

Building Your Own Model A Raspberry Pi

January 24, 2013 by Brian Benchoff 26 Comments

When the Model A Raspberry Pi is released in the coming weeks or months, you’ll have the opportunity to buy an even cheaper ARM Linux computer that will draw 1/3rd the power of the classic Model B. Some people just can’t wait a month to get their hands on it, so [Blair] decided to make his own.

The Model A Raspberry Pi is nearly the same as the Model B; the only things missing are an Ethernet port, a single USB port, and the associated chips required to drive these ports. In a brave bit of desoldering, [Blair] removed the Ethernet/USB controller with a butane torch.

In part two of [Blair]’s adventures, he removed the Ethernet connector and replaced the two-high USB ports with a single port, greatly decreasing the height of the Raspberry Pi.

As of right now, this is just about the only way to get your hands on the lower power, more compact Raspberry Pi. We can’t wait, though, for the eventual tutorial of how to turn a Model A into a Model B. That’ll be an awesome demonstration of god-like soldering skills.

Raspberry Pi Becomes A Torrent Box

January 24, 2013 by Brian Benchoff 71 Comments

If you’re making a media server out of a Raspberry Pi, why not add an interface to the biggest torrent sites on the Internet? That’s what [Alan] did when he wanted an automated media downloader that can stream movies and TV shows to any device.

[Alan]’s torrent box is basically a web app running on a Raspberry Pi. By accessing the Pi from the browser of a desktop or mobile device, he can search a collection of torrent sites and download just about everything to the Pi with a touch of a button. Once the files are downloaded, the Pi is able to move them to any directory, either locally or on a network, or just serve them up on a TV with a media player.

While we’re not endorsing file sharing, we can’t think of a simpler way to set up a seedbox that draws a minuscule amount of power. It’s a great addition to any media server, and a great way to get the latest season of <<Linux Distribution>> streaming to your TV.

Replacement Controllers For Slot Car Racing

January 23, 2013 by Mike Szczys 11 Comments

replacement-controllers-for-slot-car-racing

That blur on the right is a car racing into the frame. But look around the rest of the image and you’ll see the area is littered with extra hardware. [Matthew], [Doug], and [Barry] have been hard at work adding extra functionality and replacing the original controllers on this Scalextric slot car setup. So far it looks like their build log has not caught up with all the work they’ve done. We’re hoping to learn more details as they have time to write about them (this is coursework at University so we’re sure there’s a lot on their plates). But for now there are several videos and a gallery of images to drool over.

The cars are controlled by the voltage level in the track. The team replaced the stock controllers with a Raspberry Pi. It manages that voltage using Pulse-Width Modulation via MOSFETs. This allows the races to be automated but also makes it simple for a human operator to use just about any input device imaginable to control the cars. For good measure they also added a lap counter that uses an IR LED and detector to sense when a car passes the finish line.

After viewing several of their videos we think the goal of the project is to log the fasts times without sending the cars flying off the tracks during the turns.

Raspberry Pi Plays MIDI Without An Operating System

January 22, 2013 by Brian Benchoff 14 Comments

[youtube=http://www.youtube.com/watch?v=k6TCysv6AzE&w=580]

For all the interesting DSP functions locked away in the Raspberry Pi, it’s still hard to imagine using the Raspberry Pi as an eminently capable software synthesizer, tracker, or sequencer. Running any of the usual Linux digital audio programs means – surprise – running Linux, and the performance penalty associated with that.

It would be much better if all these audio programs could run directly on the Raspberry Pi without an operating system, and [Joe]’s project is right up that alley. He’s playing MIDI files without an operating system, in effect making the Raspberry Pi a very powerful embedded platform.

[Joe]’s build is the first bare metal audio code for the Raspberry Pi. It’s actually an LV2 plugin host that will load audio plugins, read MIDI files, and shoot the resulting audio out over the 1/8″ jack on the Pi. This work wouldn’t have been possible without a few Raspberry Pi bare metal tutorials put together by [David Welch].

Hopefully this won’t be the last we’ll see of [Joe] and his code; the Raspberry Pi has more than enough horsepower to be an amazing sampler, synth, beat machine, or the next generation of Akai MPC. All we need are a few brave coders to take up coding bare metal on the Raspberry Pi.

Raspberry Pi Power Controller Adds Shutdown And Startup Functionality

January 17, 2013 by Mike Szczys 22 Comments

This breadboarded circuit uses a PIC chip to control the Raspberry Pi’s power supply. We first noticed this gap in the RPi features when we built an XBMC setup around the RPi board. It’s not the end of the world, but since installing the Raspberry Pi we have been unplugging it after each use. [Kevin Sangeelee’s] circuit could be the path to automating this process.

This is not really aimed at media applications. The PIC circuit does switch power to the RPi, but the goal was to add a push-button to do so. Other goals of the project include scheduled shutdown and data logging of brownout events on the power rail. As you can see, there’s a coin cell in the mix which keeps time when the system is in power down. The RPi communicates with the PIC via i2c. This facilitates full power-down using the Linux command ‘shudown -h’, as well as the ability to schedule a restart time.

Adding an IR receiver and tweaking the PIC code are all it would take to trigger the power controller from the couch.

[Thanks Donn]

Raspi Astrophotography Board Also Does Everything Else

January 17, 2013 by Brian Benchoff 17 Comments

FPGA

A few years ago the folks at Astro Designs put together a board that took off-the-shelf CCD sensors from point and shoot cameras and turned them into respectable astrophotography sensors. Since then, the world has seen an explosion of Raspberry Pis, Arduinos, and other microcontroller platforms, making this the perfect time for a hardware revision.

Their PiXi-200, like their previous AstroCam board, is able to take image sensors out of cameras and turn them into telescope mounted cameras. That’s only one of its tricks, though: The PiXi-200 also has accelerometers, gyroscopes, enough UARTs to do just about anything, a four channel ADC and four channel DAC, two dozen GPIO pins, enough LEDs and buttons for any project, and a 200,000 gate FPGA. All this in a board that plugs directly into the GPIO pins on the Raspberry Pi just like an Arduino shield. Needless to say, there’s a lot you can do with this board.

Right now, the design is still in the prototype stage, but once everything is finalized the basic model of the board will sell for £30 GBP ($50 USD). The high-end “Model C” board, with all the bells and whistles, will sell for £45 GPB ($70 USD).