Today, the Lixie Display was officially deemed open by the Open Source Hardware Association! (OSHWA for short.) This means that a member of the OSHWA board has manually checked that I'm properly sharing all documentation in an open, (Fritzing) or "free" format. (Eagle Free Version)
Because of this, I'd like to cover two things:
- The OSHW certification process
- Lixie's open hardware!
After seeing this wonderful talk by SparkFun founder Nathan Seidle a few months ago, I decided that the Lixie display would be as open as possible. There's nothing you can do to stop a copy cat, so you might as well be friendly!
If your idea can be sold, it will be.
On December 9th, I submitted Lixie's documentation (available on the Github) to OSHWA through their online form. The "Certification Mark License Agreement" took about 30 minutes to complete with reading to make sure I wasn't signing my soul to the devil, but I was very pleased with the terms. For those of you unfamiliar with the OSHW mark, it's fairly new and very cool!
The OSHW logo is a new iteration of the Open Source Hardware "Gear Logo". This gear is still valid, but has one issue: anybody can use it. This means that people who weren't open sourcing at all were using the logo purely for promotional reasons. (Dave Jones has a great video about this.) The new [OSHW] logo solves this by requiring manual approval of it's use per project with their certification process.
OSHWA replied within 48 hours, on a weekend, with my official OSHW UID of "US000054"!
Please note however, the OSHW mark is *NOT* a licence protecting the hardware from being closed by a third party, it's just a certification mark. You'll still need to bundle in a licence like The GPL v3 I use on all of my work.
In the spirit of being as Open as possible, let's take a thorough look through how Lixie works!
Lixie works by shining light through the edge of a clear acrylic. When the light hits an engraving or edge, it scatters in a different direction, and lands in your eye! This allows the flat surfaces of the acrylic to stay clear, and have only edges light up! Now put ten pieces in a stack, each marked with a different number 0-9, and you can show each number individually, on a clear surface!
To do this well, we need two things: plate separation and a light filter. Adding a gap between plates prevents light from jumping between them, and a filter at the base prevents an LED from lighting any plates but the one it's supposed to.
Each of the ten plates has a number on it, 0 through 9. For maximum light output, these numbers are actually cut all the way through the acrylic, with little connected areas left on numbers like "9" so that no areas are completely cut out. (Think pumpkin carving). Most laser cutters are able to produce cuts of a certain depth as to not completely cut the material, but I use Ponoko for cutting these, which only allows very shallow engraving or full-blown cutting. Each plate is separated by a 1mm air gap.
A light filter is used to prevent LEDs from lighting plates they shouldn't. Each plate has two legs leading down to two slots, over two LEDs. This filter, and the PCB beneath it, are specifically designed so that the three anodes of the 5050 RGB LEDs are centered under the slots.
Printed Circuit Board
The Lixie actually has a very simple PCB, with some very specific dimensions. To fit all of the LEDS in, they have to be staggered diagonally. Each acrylic digit has the two lightpipe legs in different spots for this reason. As mentioned above, the LEDS are also placed JUST right so that the anodes for red, green, and blue are centered under the filter slots.
Conclusion and Waiting List
I know some of you are waiting very anxiously for Lixie to go on sale, and I have good news! You can hop on a waiting list for the Tindie listing...
Read more »