The Possibility Of Driving 16,000 RGB LEDs

Like just about everyone we know, [Luis] decided a gigantic RGB LED matrix would be a cool thing to build. Gigantic LED matrices are very hard to build, though: not only do you have to deal with large power requirements and the inevitable problems of overheating, you also need to drive a boat load of LEDs. This is not easy.

[Luis] found a solution to the problem of driving these LEDs with a new, fancy ARM Cortex M4 microcontroller. All Cortex M4 ARMs have DMA, making automatic memory transfers to peripherals and LED strips a breeze.

The microcontroler [Luis] is using only supports 1024 transfers per transfer set, equating to a maximum of 14 LEDs per transfer. This problem can be fixed by using the ping-pong mode in the DMA controller by switching between data structures for every DMA request. Basically, he’s extending the number of LEDs is just switching between two regions of memory and setting up the DMA transfer.

The result is much better than [Luis]’ original circuit that was just a bunch of SPI lines. It also looks really good, judging by the video below. It’s not quite a gigantic LED matrix yet, but if you want to see what that would look like, check out the huge 6 by 4 foot matrix hanging in the Hackaday overlord office.

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Hackaday Links: January 19, 2014


[Nick] wrote in to tell us about his first blog post. He’s showing off a PWM LED driver he build around a 555 timer. This project uses a lot of basics; some 555 experience, PCB etching, and surface mount soldering. We’d like to know more about the blue substrate on his circuit board!

After seeing the BOM spreadsheet with KiCAD integration a couple of weeks back, [Vassilis] sent in a link to his own Excel-based Bill of Materials helper. We’re wondering if anyone has a similar tool that will work with Open Office?

While we’re on the topic of downloadable documents, here’s a reference PDF for all types of DC measurements. The collection is a free offering from Keithley. [Thanks Buddy]

Since you’re brushing up on your knowledge you may also be interested in a free online microcontroller course offered by UT Austin. They’re targeting the Tiva C Launchpad as the dev board for the class.

This website seems to be a little creepy, but the teardrop shaped 3D printed music box which is being shown off is actually rather neat.

Hackaday Alum [Phil Burgess] threw together a point and shoot camera for Adafruit. It’s a Raspberry Pi, camera board, touchscreen display, and USB battery all rubber banded together. The processing power of the RPi is used to add image processing effects which are shown off in the demo video.

We don’t own a DeLorean. If we did, we’d probably follow the lead of Queen’s University Belfast and turn it into and electric vehicle. [Thanks Jake]

The 3D photocopiers are coming. Here’s a hacked together proof-of-concept from [Marcelo Ruiz]. After laser scanning the part is milled from floral foam.


A Shell For The Stellaris & Tiva


When [antoker] is working on a microcontroller project, he often has to write short bits of test code to make sure everything in his circuit is working properly. This is a time-consuming task, and a while back he started on a small side project. It’s a command line interface for a microcontroller that allows him to send short commands to the uC over a serial connection to play around with the ADC, UART, and GPIO pins.

[antoker]’s tiny Unix-like environment is based on modules  that can keep track of the time, print the current commands and stack to a terminal, and query things like the current speed of the uC and the available Flash and RAM.

This tiny shell also has scripting capabilities and a jump function, making this a true programming language, however minimal it is. Right now [antoker]’s work is available for the TI Stellaris and Tiva series microcontrollers, and a video of a scripted Larson scanner is available below.

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Hackaday Links: November 24, 2013


We love home theater hacks and this one especially since it is also part of a larger home automation project. [Falldeaf] use Z-Wave wireless home automation and includes mains switching for his television. The only problem being that when power is switch back on the TV remains in the standby state. His solution was to use an ATtiny85 to detect power, then push the IR code to turn the TV on after a short delay.

[Pjkim] wanted to prototype using the Tiva Launchpad on his Mac. He managed to get a toolchain up and running that includes the TivaWare libraries. He put together a guide that shows how to set up Eclipse and Energia for the Tiva family. If you haven’t heard of Energia check out the Github Readme.

Most folks have a smartphone and you can bet that the handsets are Bluetooth enabled. But we think there is still a low percentage who are connecting their smartphone audio to wireless speakers. [Anton Veretenenko] shows how you can use some cheap KRC-86B modules from Ali Express to make your own wireless speakers. He’s even powering his hack with a single 18650 Li-Ion cell.

Taking a turn away from electronics we got a chuckle out of [CADFood’s] plan to make pearls with his bicycle. He used DesignSpark Mechanical to model what amounts to a bicycle powered ball mill. It attaches to his spokes and after taking a hammer to some oyster shells he loads them up and goes for a ride. Well actually he needs to go for a bunch of rides. The idea is that about six months of bicycling will yield a cache of pearls. [Thanks Holger]

We enjoyed this article on how designing powered scooters is changing engineering education. We’re happy to see that hacking is starting to be widely accepted as a functional and effective way to gain and pass on knowledge.

If you have access to a 3D printer you can own some of the relics from the Smithsonian. They’ve been 3D scanning some pieces in their collection and you can download the models.

And finally, [GravityRoad] is working on building a delta-bot arm to use as part of a performance art project. Check out one of the most recent development videos and if that gets you interested there’s much more on the website. [Thanks Charles]