An Introduction To Individually Addressable LED Matrices

April 26, 2015 by Brian Benchoff 8 Comments

The most fascinating project you can build is something with a bunch of blinky hypnotic LEDs, and the easiest way to build this is with a bunch of individually addressable RGB LEDs. [Ole] has a great introduction to driving RGB LED matrices using only five data pins on a microcontroller.

The one thing that is most often forgotten in a project involving gigantic matrices of RGB LEDs is how to mount them. The enclosure for these LEDs should probably be light and non-conductive. If you’re really clever, each individual LED should be in a light-proof box with a translucent cover on it. [Ole] isn’t doing that here; this matrix is just a bit of wood with some WS2812s glued down to it.

To drive the LEDs, [Ole] is using an Arduino. Even though the WS2812s are individually addressable and only one data pin is needed, [Ole] is using five individual data lines for this matrix. It works okay, and the entire setup can be changed at some point in the future. It’s still a great introduction to individually addressable LED matrices.

If you’d like to see what can be done with a whole bunch of individually addressable LEDs, here’s the FLED that will probably be at our LA meetup in two weeks. There are some crazy engineering challenges and several pounds of solder in the FLED. For the writeup on that, here you go.

Linear Book Scanner Does It With Arduino

April 23, 2015 by Kristina Panos 26 Comments

About two and half years ago, the Google Books team open-sourced the plans for their book scanning rig, and there was much rejoicing. As [Dany Qumsiyeh] explained in the Google Tech talk we linked to at the time, the scanner uses a vacuum to lift the next page from the stack and turn it, saving hours of human labor and, admittedly, putting books in a little bit of danger.

[Chris] tipped us off about a different take on the linear book scanner created by [Forssa1] that uses server fan to turn the pages. [Forssa1]’s rig is built from laser-cut acrylic and employs two handheld scanners driven by an Arduino Mega. We don’t have a great deal of information about this build, but you can check it out after the break.

UPDATE: [Forssa1] checked in with us and sent a link to more build photos of his book scanner.

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ASCII Art With Pure Data And A Typewriter

April 21, 2015 by Brian Benchoff 19 Comments

[vtol] is quickly becoming our favorite technological artist. Just a few weeks ago he graced us with a Game Boy Camera gun, complete with the classic Game Boy printer. Now, he’s somehow managed to create even lower resolution images with a modified typewriter that produces ASCII art images.

As with everything dealing with typewriters, machine selection is key. [vtol] is using a Brother SX-4000 typewriter for this build, a neat little daisy wheel machine that’s somehow still being made today. The typewriter is controlled by an Arduino Mega that captures an image from a camera, converts it to ASCII art with Pure Data and MAX/MSP, then slowly (and loudly) prints it on a piece of paper one character at a time.

The ASCII art typewriter was recently shown at the 101 Festival where a number of people stood in front of a camera and slowly watched a portrait assemble itself out of individual characters. Check out the video of the exhibit below.

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Driving A Brushless DC Motor Sloooooooowly

April 20, 2015 by Will Sweatman 68 Comments

Driving a brushless DC (gimbal) motor can be a pain in the transistors. [Ignas] has written up a nice article not only explaining how to do just this with an Arduino, but also explaining a little bit on how the process works. He uses a L6234 Three Phase Motor Driver, but points out that there are other ways to interface the BLDC motor with the Arduino.

A warning is warranted – this is not for the faint of heart. You can easily destroy your microcontroller if you’re not careful. [Ignas] added several current limiting resistors and capacitors as advised in the application note (PDF warning) to keep things safe.

Everything worked well at high speeds, but for slower speeds the motor was choppy. [Ingus] solved this riddle by changing over to a sine wave to drive the motor. Instead of making the Arduino calculate the wave, he used a look up table.

Be sure to check out his blog for full source and schematics. There is also a video demonstrating just how slow he can make the motor move below.

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Your Arduino Packaging Could Sway A Court Case

April 19, 2015 by Mike Szczys 115 Comments

Our friends over at Adafruit just made an interesting suggestion regarding the Arduino vs. Arduino saga. They noticed that the packaging for the Arduino UNO includes a pamphlet that states:

Manufactured under license
from Arduino by
SMART PROJECTS S.r.l.

Wow. That’s pretty interesting. Smart Projects is the former name of Arduino SRL. If you missed it, go back and read some of our previous coverage. Specifically, Arduino SRL is claiming to be the real trademark holder and has gone as far as forking the Arduino IDE and upping the version number in what appears to be an attempt to direct users toward their newly founded Arduino.org website/ecosystem/quagmire. If they feel they own the trademark why would they include this statement in their packaging?

Finding this in the a unit from a September 2014 is interesting. But Adafruit’s post is a call to action. We share their curiosity of discovering how far back official Arduino hardware has included such license notices. So, head on down to your work bench… start peeling back years worth of discarded hacks, clipped leads, fried servos, and other detritus. Find the packaging and take a picture. Bonus points if you have an invoice that associates a date with it. Either way, post the pictures on your social media hub of choice with #TeamArduinoCC. You can also embed it in the comments using HTML IMG tags if you wish.

Standard “I am not a lawyer” disclaimer applies here. We know you aren’t either so let’s all share what we think this means to pending lawsuits in the comments. Does this matter and why?

Energia Multitasking Uses RTOS On MSP432

April 17, 2015 by Mike Szczys 49 Comments

We keep wondering where the Arduino world is headed with the hardware getting more and more powerful. If the IDE doesn’t keep up what’s the point? Now we have at least one answer to that problem. Energia is the Arduino-like-framework for Texas Instruments based boards. They just came out with a multitasking system built into Energia targeted at the ARM Cortex-M4F based MSP432 Launchpad which we covered a few weeks back.

The announcement post gives a couple of examples of uses for multitasking. The simplest is blinking LEDs at different rates. If you wanted to do this closer to the metal you’re talking about multiple timers, or multiple compares on a single timer, perhaps a interrupt-driven-system-tick that has a high enough resolution for a wide range of your blinking needs. But these are not always easy to set up unless you are intimately comfortable with this particular architecture. The Energia multitasking will handle this for you. It’s upon the TI Real Time Operating System (TI-RTOS) but wraped in the familiar IDE.

The UI divorces you from thinking about the hardware at all. You simply launch a new tab and start coding as if you’re using a completely separate piece of hardware. The announcement post linked above mentions that these Sketches are running “in parallel”. Well… we know it’s not a multi-core system like the Propeller but we’ll let it slide. It is certainly easier than building your own scheduler for this type of hardware.

[Thanks MycoWx]

Play Robotic Bongos Using Your Household Plants

April 16, 2015 by Theodora Fabio 2 Comments

[Kirk Kaiser] isn’t afraid to admit his latest project a bit strange, being a plant-controlled set of robotic bongos. We don’t find it odd at all. This is the kind of thing we love to see. His project’s origins began a month ago after taking a class at NYC Resistor about creating music from robotic instruments. Inspired to make his own, [Kirk] repurposed a neighbor’s old wooden dish rack to serve as a mount for solenoids that, when triggered, strike a couple of plastic cowbells or bongo drums.

A Raspberry Pi was originally used to interface the solenoids with a computer or MIDI keyboard, but after frying it, he went with a Teensy LC instead and never looked back. Taking advantage of the Teensy’s MIDI features, [Kirk] programmed a specific note to trigger each solenoid. When he realized that the Teensy also had capacitive touch sensors, he decided to get his plants in on the fun in a MaKey MaKey kind of way. Each plant is connected to the Teensy’s touchRead pins by stranded wire; the other end is stripped, covered with copper tape, and placed into the soil. When a plant’s capacitance surpasses a threshold, the respective MIDI note – and solenoid – is triggered. [Kirk] quickly discovered that hard-coding threshold values was not the best idea. Looking for large changes was a better method, as the capacitance was dramatically affected when the plant’s soil dried up. As [Kirk] stood back and admired his work, he realized there was one thing missing – lights! He hooked up an Arduino with a DMX shield and some LEDs that light up whenever a plant is touched.

We do feel a disclaimer is at hand for anyone interested in using this botanical technique: thorny varieties are ill-advised, unless you want to play a prank and make a cactus the only way to turn the bongos off!

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