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Monthly Archives: September 2015

Led Clock Saga

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Having moved into my apartment a while back one thing remained missing for a long time; a clock. It sounds simple but I wanted a rather large and eye-catching clock. Those turned out not to be cheap nor very innovative. This is the story of the quest for changing that, by making my own clock with the help of Wouter Jansen and Bart Bilos.

Design

As everyone probably knows, LEDs make things better. These days they are more accessible, easy to use and program than ever and thus the idea was born to make a clock out of a string of 2 meters of addressable LED strip. As if the chinese manufacturer knew, these strips feature 60 LEDs per meter, which is quite an easy coincidence when trying to build a clock.

Lasercutting

With the help of Wouter, a design was made to create a frame and plexiglass rim using a laser cutter. It would mean having to glue a lot of stuff together, and even more challenging – doing a decent paint job on it, but we accepted that challenge since it was the only way of creating the 2M circumference circle we wanted.

Construction

It took a lot of time putting it all together but the result was simply stunning. The software is running on an Arduino and the clock is not limited to just showing the time but can show you everything that you’d want to display on it, such as a VU or spectrum meter (which works awesome at a housewarming or any other party).

[su_youtube url=”https://www.youtube.com/watch?v=f-kzLQ0qZkk”]

Ever since we made the clock, a lot of positive reactions followed regarding it’s looks and if it was commercially available. We do have plans to make a first prototype production run to build some more clocks for the people who want one and perhaps a KickStarter campaign in the future, as we think this could be a nice clock for the masses. If you’re interested drop us a line! Suggestions of future expandability are also welcome.

A more technical blogpost about how it all works and what’s in it will follow shortly.

Led Clock Saga (Part 2)

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After writing my first post on the clock many people remarked that it all sounded and looked nice, but there was no actual picture or movie showing the actual clock mode. So, without further ado, here it is in all it’s glory! The colors are fully customizable but in my setup blue is the seconds, green the minutes and red the hours.

[su_youtube url=”https://www.youtube.com/watch?v=NL_uqgPF9eI”]

The clock in action shows the second hand fluidly fading between LEDs, trying to give people the impression through the fade and the plexiglass diffuser that there are no actual discrete LEDs but a continuously updating fluid clock (same applies for minute and hour hands but this is not visible unless looking at the clock for longer periods).

[su_youtube url=”https://www.youtube.com/watch?v=fTEPlaHdcSI”]

Wouter lent me his Spark Core to port the software on to and to make it a proper internet connected clock. I did just that and what’s cool is that the clock is now IFTTT enabled. In the video you can actually see me being notified on a new follower on Twitter, the rule for that in IFTTT is as simple as:

Screen Shot 2015-03-13 at 15.36.01

Notice the data? It’s the hex color for the notification! It allows you to do all kind of cool stuff, here’s my list of current recipes but the sky is the limit in terms of notifications based on this. Future plans on this function include adding some other animations and persistent notifications (e.g. a small blue glow when it’s raining or red when you have missed calls, while the time is still moving).

Screen Shot 2015-03-13 at 15.38.57

So a lot of new functionality in the code and the way the clock works now. It’s getting more and more mature! Wouter also did a mockup for our new version of the clock of which we still plan to do a prototype run for people that are interested (contact us!) which incorporates lenses for each of the LEDs allowing a diffuse and discreet lighting, which will make the clock easier to read.

[su_youtube url=”https://www.youtube.com/watch?v=rNuZwFnE9mA”]

Prism effect 3 (web)That’s all for now, if anybody wants to know more about specific things, feel free to ask or drop us a line. Stay tuned for more functionality and updates.

Brightness, Analog > Digital

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One of the annoyances with my led clock has been that it is too bright during the evening. But, that can be easily solved by adding some kind of brightness control… This is the tale of that feature.

So, brightness control. There’s an awesome digital light sensor that can give you resolutions up to 16 bits and provides on chip lux conversion for getting numbers out of it that actually make sense (On high resolution you’ll get a number between 1 an 65535 lux) . It’s called a BH1750 and it is cheaply available everywhere. Connecting it over I2C is a breeze and there are lots of good libraries available for this chip, even for my Spark Core.

BH1750 Spark Core

Hooking it up to your Spark is a breeze and I wrote a small brightness controller with a running average trick in it to smoothen the transitions between different light readings. More on how that works later, first let me tell you this thing is simply not fast enough. As the main loop that makes sure there’s continuously fading between pixels (limited at 30 refreshes per second) even on low resolution the BH1750 needs 16ms for a measurement which gives a notable hick-up. Since you can’t do it async I decided to ditch the digital way and go for analog instead.

Photoresistor Spark Core

The Spark Core has 8 analog ports (A0 till A7), which give a 12bit accuracy when reading an analog value on it. This allows us to connect the photo-resistor with only a few components to the Spark Core and then reading it’s voltage gives a pretty good resolution and most important without any delays. Of course the numbers returned are not saying that much, so what I did in code was add a minimum and maximum threshold and minimum and maximum brightness of the LEDs so you can actually tweak how the brightness controller reacts to changes.

Mapping the numbers from the one range to the other is as simple as Y = (X – A) / (B – A) * (D – C) + C, where X is the number we get out of the reading, A is the minimum threshold, B the maximum threshold, C the minimum brightness and D the maximum brightness. Y of course is the outcome and before doing this you’ll need to check if X is below or above the thresholds since then you could directly write the minimum or maximum brightness, depending on X being above or below.

 

Moving Average

Getting back to the running average I’ve added, what it does is dampen the peaks or lows the circuit might give due to instability but also provide smooth fading between brightnesses (see graph above to illustrate this principle). This excellent tutorial on the Arduino website describes perfectly how to do it and gives you a nice library if you’d wish to integrate it into your own program. My own version of it is tailored to my specific needs (who needs floats anyway!).

LightSaga

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Time for an update on the led clock project by me and Wouter Jansen. A lot of things have happened recently; We’ve send out a call to action to all the people who’ve shown interest in investing into the first prototype run and the we’re happy to announce that our first prototype run is not only funded successfully, but also almost sold out. With prices at 350 euros for the original and 250 euros for the smaller version we are very grateful for the support and hope that all the people that believe in us will be very happy with their hand build limited edition clocks.

35 & 70 cm clock.20

Furthermore, we decided on a name for the whole project and have launched a website for the clock as well. The official name will henceforth be LightSaga and you can find the official website at http://www.lightsaga.com. The site features some production renders of how the current clock will look once it’s done.

IMG_20150611_173351

In terms of production we are making good progress. The first Photons arrived as well as the acrylic rings and we hope to receive the aluminum parts this week. After that we need to assemble, test and program them all. This puts the scheduled delivery date somewhere past the summer so we have some time to do all the things that need to be done.

We’ll be keeping you updated throughout the whole build process so be sure to keep checking back on this blog for more information. Also, a couple of clocks are still available for sale so while the supply last you can still get your hands on one!

The OSH Park Experience

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For the LightSaga project we have designed some custom boards that will house the Photons, light sensor, some capacitors for stability and a logic level converter. Nothing too fancy but a good chance to let these prototypes be produced by OSH Park, well known for their purple PCBs.

IMG-20150626-WA0000

One of the really awesome features of OSH Park is that you can upload your Eagle board directly instead of first having to export all the Gerber files. Of course you can also upload the Gerbers but why would you when just uploading your Eagle files is so much faster and easier. Once uploaded the website will show you very nice purple renderings of what your produced board will look like including all the layers which you can visually inspect to make sure everything looks like you want.

Screen Shot 2015-07-17 at 14.41.35They also provide an Eagle DRU file (design rules) which you can run to make sure your board abides to their specifications. I think I saved many hours with these very helpful features. You can try this with one of your Eagle boards right now, just go to their website and upload your .BRD file.

OSH Park PCB’s have a ENIG finish which stand for Electroless nickel immersion gold. ENIG being a chemical process results in excellent surface planarity as opposed to HASL (hot air solder levelling) which leaves behind visible irregularities. The quality of OSH Park PCB’s is top notch. The pads show a perfect finish and the solder mask apertures have excellent tolerance.

So I want to really give OSH Park a thumbs up and recommend it for small prototyping batches as well as production PCBs. I think they are superior to the Chinese PCB makers in terms of quality and turnaround time. Pricing is very competitive (DirtyPCBs has a nice offer for prototype packs but is inferior in quality).

If you’re interested in how OSH Park does it, be sure to read this interview.

Limited number of prototype run LightSagas now for sale! I WANT ONE!