FPGA Powers Blazingly Fast LED Matrix Audio Visualizer

[Sam Miller], [Sahil Gupta], and [Mashrur Mohiuddin] worked together on a very fast LED matrix display for their final project in ECE 5760 at Cornell University.

Real time!
Real time!

They started, as any good engineering students, by finding a way to make their lives easier. [Sam] had built a 32×32 LED matrix for another class. So, they made three more and ended up with a larger and more impressive 64×64 LED display.

They claim their motivation was the love of music, but we have a suspicion that the true reason was the love all EEs share for unnaturally bright LEDs; just look at any appliance at night and try not be blinded.

The brains of the display is an Altera DE2-115 FPGA board. The code is all pure Verilog. The FFT and LED control are implemented in hardware on the FPGA; none of that Altera core stuff. To generate images and patterns they wrote a series of python scripts. But for us it’s the particle test shown in the video below that really turns our head. This system is capable of tracking and reacting to a lot of different elements on the fly why scanning the display at about 310 FPS. They have tested display scanning at twice that speed but some screen-wrap artifacts need to be worked out before that’s ready for prime time.

The team has promised to upload all the code to GitHub, but it will likely be a while before the success hangover blows over and they can approach the project again. You can view a video interview and samples of the visualizations in the videos after the break.

Thanks to their Professor, [Bruce Land], for submitting the tip! His students are always doing cool things. You can even watch some of his excellent courses online if you like: Here’s one on the AVR micro-controller.

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Learn To Program With Literate Programming

My heyday in programming was about five years ago, and I’ve really let my skills fade. I started finding myself making excuses for my lack of ability. I’d tackle harder ways to work around problems just so I wouldn’t have to code. Worst of all, I’d find myself shelving projects because I no longer enjoyed coding enough to do that portion. So I decided to put in the time and get back up to speed.

Normally, I’d get back into programming out of necessity. I’d go on a coding binge, read a lot of documentation, and cut and paste a lot of code. It works, but I’d end up with a really mixed understanding of what I did to get the working code. This time I wanted to structure my learning so I’d end up with a more, well, structured understanding.

However, there’s a problem. Programming books are universally boring. I own a really big pile of them, and that’s after I gave a bunch away. It’s not really the fault of the writer; it’s an awkward subject to teach. It usually starts off by torturing the reader with a chapter or two of painfully basic concepts with just enough arcana sprinkled in to massage a migraine into existence. Typically they also like to mention that the arcana will be demystified in another chapter. The next step is to make you play typist and transcribe a big block of code with new and interesting bits into an editor and run it. Presumably, the act of typing along leaves the reader with such a burning curiosity that the next seventeen pages of dry monologue about the thirteen lines of code are transformed into riveting prose within the reader’s mind. Maybe a structured understanding just isn’t worth it.

I wanted to find a new way to study programming. One where I could interact with the example code as I typed it. I wanted to end up with a full understanding before I pressed that run button for the first time, not after.

When I first read about literate programming, my very first instinct said: “nope, not doing that.” Donald Knuth, who is no small name in computing, proposes a new way of doing things in his Literate Programming. Rather than writing the code in the order the compiler likes to see it, write the code in the order you’d like to think about it along with a constant narrative about your thoughts while you’re developing it. The method by which he’d like people to achieve this feat is with the extensive use of macros. So, for example, a literate program would start with a section like this:

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Secret Listening to Elevator Music

While we don’t think this qualifies as a “fail”, it’s certainly not a triumph. But that’s what happens when you notice something funny and start to investigate: if you’re lucky, it ends with “Eureka!”, but most of the time it’s just “oh”. Still, it’s good to record the “ohs”.

Gökberk [gkbrk] Yaltıraklı was staying in a hotel long enough that he got bored and started snooping around the network, like you do. Breaking out Wireshark, he noticed a lot of UDP traffic on a nonstandard port, so he thought he’d have a look.

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Reinventing VHDL Badly

A few years ago, Philip Peter started a little pet project. He wanted to build his own processor. This really isn’t out of the ordinary – every few months you’ll find someone with a new project to build a CPU out of relays, logic chips, or bare transistors. Philip is a software developer, though, and while the techniques and theory of building hardware haven’t changed much in decades, software development has made leaps and bounds in just the past few years. He’s on a quest to build a CPU out of discrete components.

Search the Internet for some tips and tricks for schematic capture programs like KiCad and Eagle, and you’ll find some terrible design choices. If you want more than one copy of a very specific circuit on your board, you have to copy and paste. Circuit simulation is completely separate from schematic capture and PCB design, and unit testing – making sure the circuit you designed does what it’s supposed to do – is a completely foreign concept. Schematic capture and EDA suites are decades behind the curve compared to even the most minimal software IDE. That’s where Philip comes in. By his own admission, he reinvented VHDL badly, but he does have a few ideas that are worth listening to.

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K.I.S.S. Pi Sprinkler – Just Keep the Plants Alive

A good first step in a project is knowing what you want to do. [Ben Fino] made it clear that his Raspberry Pi Sprinkler control system for his wife’s garden had one goal: keep the plants alive. The resulting project is doing just that and no more.

The circuitry, and plumbing, is straightforward and explained well in the Instructable. All the electronics consists of is the Pi and a MOSFET to take the 3.3v GPIO to 5v to control a relay. The valve controlling the water requires 28v AC which necessitated the relay to control it. There are also three LEDs: one is for power, one to indicate when the valve is opened, and one is an extra for some future purpose.

The intriguing part is the use of weather data from the web to determine if it’s rained recently. Python scripts provided by [Ben’s] friend [Mark Veillette] use a weather site API to get the rainfall data. The main script is set to run once every 24 hours. [Ben] set his system to water unless the previous day had sufficient rain. How much rain and the number of look-back days is programmable.

What a great application of the KISS principle: keep it simple, stupid – except for that third LED without a purpose.

Circuit Bender Artist bends Fresnel Lens for Art

Give some mundane, old gear to an artist with a liking for technology, and he can turn it into a mesmerizing piece of art. [dmitry] created “red, an optic-sound electronic object” which uses simple light sources and optical elements to create an audio-visual performance installation. The project was the result of his collaboration with the Prometheus Special Design Bureau in Kazan, Russia. The inspiration for this project was Crystall, a reconstruction of an earlier project dating back to 1966. The idea behind “red” was to recreate the ideas and concepts from the 60’s ~ 80’s using modern solutions and materials.

The main part of the art installation consists of a ruby red crystal glass and a large piece of flexible Fresnel lens, positioned in front of a bright LED light source. The light source, the crystal and the Fresnel lens all move linearly, constantly changing the optical properties of the system. A pair of servos flexes and distorts the Fresnel lens while another one flips the crystal glass. A lot of recycled materials were used for the actuators – CD-ROM drive, an old scanner mechanism and old electric motors. Its got a Raspberry-Pi running Pure Data and Python scripts, with an Arduino connected to the sensors and actuators. The sensors define the position of various mechanical elements in relation to the range of their movement. There’s a couple of big speakers, which means there’s a beefy amplifier thrown in too. The sounds are correlated to the movement of the various elements, the intensity of the light and probably the color. There’s two mechanical paddle levers hanging in there, if you folks want to hazard some guesses on what they do.

Check out some of [dmitry]’s earlier works which we featured. Here’s him Spinning a Pyrite Record for Art, and making Art from Brainwaves, Antifreeze, and Ferrofluid.

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KiCAD BOM Management

KiCAD remains a popular tool for designing PCBs and other circuits, and with good reason: it’s versatile and it’s got pretty much everything needed to build any type of circuit board you’d want. It also comes with a pretty steep learning curve, though, and [Jeff] was especially frustrated with the bill of materials (BOM) features in KiCAD. After applying some Python and Kivy, [Jeff] now has a BOM manager that makes up for some of KiCAD’s shortcomings.

Currently, the tool handles schematic import, like-component consolidation, and a user-managed parts database that can be used to store and retrieve commonly used parts for the future. All of the changes can be saved back to the original schematic. [Jeff] hopes that his tool will save some time for anyone who makes more than one PCB a year and has to deal with the lack of BOM features native to KiCAD.

[Jeff] still has some features he’d like to add such as unit tests, a user guide, and a cleaner user interface. What other features are you anxious to see added to KiCAD?

This script is a great tool for anyone who has had similar frustrations. KiCAD is popular to modify and expand, too: there have been tools for mechanical CAD export, a parts-generator and cost-tracker, and an Eagle to KiCAD converter if you’re thinking of making the switch.