Controlling Ten Thousand RGB LEDs

RGB LEDs are awesome – especially the new, fancy ones with the WS2812 RGB LED driver. These LEDs can be individually controlled to display red, green, and blue, but interfacing them with a microcontroller or computer presents a problem: microcontrollers generally don’t have a whole lot of RAM to store an image, and devices with enough memory to do something really cool with these LEDs don’t have a real-time operating system or the ability to do the very precise timing these LEDs require.  [Sprite_tm] thought about this problem and came up with a great solution for controlling a whole lot of these WS2812 LEDs.

[Sprite] figured there was one device on the current lot of ARM/Linux boards that provides the extremely precise timing required to drive a large array of WS2812 LEDs: the video interface. Even though the video interface on these boards is digital, it’s possible to turn the 16-bit LCD interface on an oLinuXino Nano into something that simply spits out digital values very fast with a consistent timing. Just what a huge array of RGB pixels needs. Using a Linux board to drive RGB pixels using the video output meant [Sprite_tm] needed video output. He’s running the latest Linux kernel, so he didn’t have the drivers to enable the video hardware.

Not a problem for [Sprite], as he can just add a few files to define the 16-bit LCD interface and add the proper display mode. [Sprite_tm] already taken an oscilloscope to his board while simulating 16 strips of 600 LEDs, and was able to get a frame rate of 30 fps. That’s nearly 10,000 LEDs controlled by a single €22/$30USD board. Now the only obstacle for building a huge LED display is actually buying the RGB LED strips. A little back-of-the-envelope math tells us a 640×480 display would be about $50,000 in LEDs alone. Anyone know where we can get these LED strips cheap?

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A Low Cost Dual Discriminator Module for the Easy-phi Project

A few months ago I presented you the Easy-phi project, which aims at building a simple, cheap but intelligent rack-based open hardware/software platform for hobbyists. With easy-phi, you simply have a rack to which you add cards (like the one shown above) that perform the functions you want.

Recently my team finished testing our FPGA-based discriminator or “universal input” if you prefer. As easy-phi cards use a well-defined electrical signal to communicate with each other, we needed to make a card that would translate the different kinds of electrical signals from the outside, as well as perform plenty of other functions. It was therefore designed to have a 100MHz input bandwidth with an AC/DC coupled 50 ohm/high impedance input stage (x2) and 4 easy-phi outputs.

For this module, we picked the (old) spartan3-an FPGA to perform the different logic functions that may be needed by the final users (high speed counter, OR/XOR/AND, pulse creation,…). Using the cortex-m3 microcontroller present on the board, it may be easily reconfigured at will. All design resources may be found on our Github, and you can always have a look at our official website.

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Building An Engine Control Unit With The STM32F4

If you’re looking to soup up your whip, the first place you’ll probably look is the engine control unit. This computer shoved in the engine compartment controls just about every aspect of your car’s performance, from the air/fuel ratio, the ignition timing, and the valve controls. Upgrading the ECU usually means flashing new firmware on the device, but [Andrey] is taking it one step further: he’s building his own ECU using the STM32F4 Discovery dev board.

[Andrey]‘s ride is a 1996 Ford Aspire, but while he was developing his open source ECU, he wanted to be able to drive his car. No problem, as going down to the junkyard, picking up a spare, and reverse engineering that was a cheap and easy way to do some development. After powering this spare ECU with an ATX supply, [Andrey] was able to figure out a circuit to get sensor input to his microcontroller and having his dev board control the fuel injector.

With a few additional bits of hardware [Andrey] has his open ECU controlling the fuel injection, ignition, fuel pump, and idle air valve solenoid. Not a bad replacement for something that took Ford engineers thousands of man hours to create. [Andrey]‘s ECU actually works, too. In the video below, you can see him driving around a snow-covered waste with his DIY ECU controlling all aspects of the engine. If the engine sounds a little rough, it’s because a wire came loose and he was only using two cylinders. A bit of hot glue will fix that, though.

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