Blink A Pi, Win A Prize

August 21, 2018 by Brian Benchoff 5 Comments

You can plug in a Raspberry Pi, and you can blink a LED. You can visualize data, and now there’s a contest on Hackaday.io to show off your skills. Right now, we’re opening up the Visualize It With Pi contest on Hackaday.io. The challenge? Visualize data with LED strips and panels. Is that ‘data’ actually just a video of Never Gonna Give You Up? We’ll find out soon enough.

The goal of this contest is to combine a Raspberry Pi and its immense processing power and the blinky goodness of LED strips and panels to visualize and interpret data in novel and artistic ways. We’re looking for animation. clarity, and flamboyant flickering. Want some ideas? Check out the World of Light or the American Constitution Candle. We’re looking for the most blinky you can do with a Pi, and yes, there will be prizes.

Prizes

Prizes for the best blinky include, of course, more blinky. The best visualizations from a directly connected sensor, data from an Internet Source, and data from an esoteric data source will each receive some Blinkytape. This is a strip of WS2812b LEDs with an ATMega32u4 embedded on the end. Plug a USB power supply into the Blinkytape, and you get a strip of LEDs in whatever color you want with the ability to push animation frames to the chip on the strip. The Grand Prize winner for this contest will also receive Blinkytile Explorers Kit, a Serpentine LED strip, a LED ring, and two meters of ultra thin LED strip.

Let’s Do This!

The requirements for the contest are simple: just use a Raspberry Pi to drive LED strips or panels, post it as a new project on Hackaday.io, and submit the project to the contest. We’re looking for a full description, source, schematics, and photos and videos of the finished version of the project — do everything you can to show off your work! The contest is open right now, and ends at 08:00 Pacific on October 1st. We know you like to blink those LEDs, so get crackin’.

An LED You Can Blow Out, With No Added Sensor

August 21, 2018 by Donald Papp 43 Comments

We’d seen it done with buttons, switches, gestures, capacitive touch, and IR remote, but never like this. [electron_plumber] made an LED that can be blown out like a candle, and amazingly it requires no added sensors. The project uses an Arduino to demonstrate turning a tiny LED on and off in response to being blown on, and the only components are the LED and a resistor.

[electron_plumber] used an 0402 LED and thin wires to maximize the temperature responses.

How is this done? [electron_plumber] uses an interesting property of diodes (which are the “D” in LED) to use the LED itself as a temperature sensor. A diode’s voltage drop depends on two things: the current that is being driven through the diode, and the temperature. If the current is held constant, then the forward voltage drop changes reliably in response to temperature. Turning the LED on warms it up and blowing on it cools it off, causing measurable changes in the voltage drop across the device. The change isn’t much — only a handful of millivolts — but the effect is consistent and can be measured. This is a principle [Elliot Williams] recently covered in depth: using diodes as temperature sensors.

It’s a clever demo with a two important details to make it work. The first is the LED itself; [electron_plumber] uses a tiny 0402 LED that is mounted on two wires in order to maximize the temperature change caused by blowing on it. The second is the method for detecting changes of only a few millivolts more reliably. By oversampling the Arduino’s ADC, an effectively higher resolution is obtained without adding any hardware or altering the voltage reference. Instead of reading the ADC once, the code reads the ADC 256 times and sums the readings. By working with the larger number, cumulative changes that would not register reliably on a single read can be captured and acted upon. More details are available from [electron_plumber]’s GitHub repository for LEDs as Sensors.

Embedded below is a video that is as wonderful as it is brief. It demonstrates the project in action, takes a “show, don’t tell” approach, and is no longer than it needs to be.

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When Every Last Nanoamp Matters

August 18, 2018 by Brian Benchoff 21 Comments

You can get electricity from just about anything. That old crystal radio kit you built as a kid taught you that, but how about doing something a little more interesting than listening to the local AM station with an earpiece connected to a radiator? That’s what the Electron Bucket is aiming to do. It’s a power harvesting device that grabs electricity from just about anywhere, whether it’s a piece of aluminum foil or a bunch of LEDs.

The basic idea behind the Electron Bucket is to harvest ambient radio waves just like your old crystal radio kit. There’s a voltage doubler, a rectifier, and as a slight twist, a power management circuit that would normally be found in battery-powered electronics.

Of course, this circuit can do more than harvesting electricity from ambient radio waves. By connecting a bunch of LEDs together, it’s possible to send a few Bluetooth packets around. This is pretty impressive — the circuit is using LEDs as solar cells, which normally produce about 50nA of current at 0.5V in direct sunlight. By connecting 12 LEDs in parallel and series, it manages to harvest just enough energy to run a small wireless module. That’s impressive, and an interesting entry to the Power Harvesting Challenge in this year’s Hackaday Prize.

Friday Hack Chat: LED Diffusion

August 15, 2018 by Brian Benchoff 27 Comments

A decade ago, the first Arduino projects featuring addressable RGB LEDs came on the scene, and the world hasn’t been the same since. Now we have full wall video displays with WS2812s and APA102s, wearable blinky, and entire suits of armor made of LEDs. The future is bright, and in RGB.

For this week’s Hack Chat, we’re going to be talking all about how to maintain the blinky without eye-searing brightness. It’s the LED Diffusion Hack Chat, full of tips and tricks on how to get the glowey without it being imprinted on your retina.

Our guest for this week’s Hack Chat is the incredible Becky Stern. Becky is one of the most prolific makers around and has a long history of fabricating some really, really cool stuff. She’s published hundreds of tutorials on everything from microcontrollers to computerized knitting machines, and has been featured by dozens of media outlets including the BBC, CNN, The Late Show with Colbert, VICE, and Forbes. Right now, she’s working at Autodesk with Instructables.

During this Hack Chat, we’re going to be talking all about diffusing LEDs, with topics including:

Taking some sandpaper to LEDs
Light pipes
3D printed LED enclosures
Looking into a bright blue LED with your remaining eye

You are, of course, encouraged to add your own questions to the discussion. You can do that by leaving a comment on the Hack Chat Event Page and we’ll put that in the queue for the Hack Chat discussion.

Our Hack Chats are live community events on the Hackaday.io Hack Chat group messaging. This week is just like any other, and we’ll be gathering ’round our video terminals at noon, Pacific, on Friday, August 17th. Need a countdown timer? Here ‘ya go.

Click that speech bubble to the right, and you’ll be taken directly to the Hack Chat group on Hackaday.io.

You don’t have to wait until Friday; join whenever you want and you can see what the community is talking about.

MIT Makes Washable LED Fabric

August 13, 2018 by Al Williams 16 Comments

Let’s face it, one of the challenges of wearable electronics is that people are filthy. Anything you wear is going to get dirty. If it touches you, it is going to get sweat and oil and who knows what else? And on the other side it’s going to get spills and dirt and all sorts of things we don’t want to think about on it. For regular clothes, that’s not a problem, you just pop them in the washer, but you can’t say the same for wearable electronics. Now researchers at MIT have embedded diodes like LEDs and photodetectors, into a soft fabric that is washable.

Traditionally, fibers start as a larger preform that is drawn into the fiber while heated. The researchers added tiny diodes and very tiny copper wires to the preform. As the preform is drawn, the fiber’s polymer keeps the solid materials connected and in the center. The polymer protects the electronics from water and the team was able to successfully launder fabric made with these fibers ten times.

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Old LED Light Bulbs Give Up Filaments For Spider Web Clock

August 1, 2018 by Dan Maloney 41 Comments

We love it when something common gets put to a new and unusual use, especially when it’s one of those, “Why didn’t I think of that?” situations. This digital clock with a suspended display is just such a thing.

The common items in this case were “filaments” from LED light bulbs, those meant to mimic the look of clear-glass incandescent light bulbs. [Andypugh] had been looking at them with interest for a while, and realized they were perfect as the segments for a large digital clock. The frame of the clock was formed from bent brass U-channel and mounted to an oak base via turned stanchions. The seven-segment displays were laid out in the frame and the common anodes of the LED filaments were connected together, with the cathode for each connected to a very fine wire. Each wire was directed through a random hole in the frame and channeled down into the base, to be hooked to one of the four DS8880 VFD driver chips. The anode wires form a lacy filigree behind the segments, which catch the light and make then look a little like a spider’s web. It looks great, but nicht für der gefingerpoken – the frame is at 80 VDC to drive the LED segments. The clock is synced to the UK atomic clock with a 60-kHz radio link; see the long, painful sync process in the video below.

We like the open frame look, which we’ve seen before with an equally dangerous sculptural nixie clock. And this gives us some ideas for what to do with those filament LEDs other than turning them back into a light bulb. And if [Andy] sounds familiar, it could be because he’s appeared here before. First of all resurrecting the parts bin for an entire classic motorcycle marque, and then as the designer of SMIDSY, a robot competitor in the first incarnation of the UK Robot Wars series.

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Are Patent Claims Coming For Your WS2812?

July 31, 2018 by Jenny List 115 Comments

There are some components which are used within our sphere so often as to become ubiquitous, referred to by their part number without the need for a hasty dig through a data sheet to remind oneself just what we are talking about. You can rattle a few of them off, the 555, the 741, the ESP8266, and so on.

In the world of LEDs, the part that most immediately springs to mind is the Worldsemi WS2812 addressable LED. This part consists of three LEDs in red, green, and blue, all in the same package with a serial interface allowing a chain of individually addressable multicolour lights to be created. We’ve seen them in all sorts of places, and if you don’t recognise the part number then perhaps you will by one of the names they’re sold under: Neopixel.

Yesterday we received an email from our piratical friends at Pimoroni, the British supplier of all forms of electronic goodies. Among their range they have a reasonable number of products containing WS2812s, and it was these products that had formed the subject of an unexpected cease-and-desist letter. APA Electronic are the manufacturer of the APA102 addressable LED (which you may know as the Dotstar), and their cease-and-desist asking for the products to be withdrawn from sale rests on their holding a patent for an addressable multicolour LED. We’d be very interested to hear whether any other suppliers of WS2812-based parts have received similar communications.

US patent number 8094102B2 is indeed a patent for a “Single full-color LED with driving mechanism”, which does look a lot like a WS2812. But as always, such things are not as cut-and-dried as they might first appear. The LED in the patent for example relies upon a clock line for its operation, while the Worldsemi part doesn’t. I am not a lawyer so I’d hesitate to call this a baseless and speculative move, but I suspect that there will be plenty over which the two semiconductor companies can duke it out in the courtroom.

It’s fair to say that a large part of the ethos of our movement shares something with that of the world of open-source, so news of legal manoeuvres such as this are never likely to go down well. We’re small fry in this context and our commercial influence on APA102 or WS2812 sales will be minimal, but inevitably APA’s standing in our eyes will be diminished. Companies such as Pimoroni are not the target but a piece of collateral damage in a battle between manufacturers.

Whether the patent has been violated or not can only be decided by the courts. It is not uncommon for patent holders to go after companies selling the “infringing” products in hopes that rather than risk a costly court battle, they simply adhere to the demands, in this case buying parts from APA and not from Worldsemi.

So, if you rely on addressable LEDs, watch out! There may be trouble ahead.

Header image: Tristan Robitaille [CC BY-SA 4.0].