Driving Tripix

Co-developer has been working on the code needed for driving a string of TriPix.  Now that we’ve got Art-Net receive code and TriPix transmit code, all that’s left is to merge the two together.  Should have something stable by the end of the week.

The chip which handles the low-level ethernet routines is tiny.  It’s the size of a regular 44-TQFP package, but there’s 80 pins instead.  The pins sit on a fine, fine pitch – and I’m glad the robots at the assembly shop will be handling that part of the job.  Wouldn’t want to try soldering it by hand.  

On a side note, we currently use two shops for assembly.  One is in Asia.  They do fantastic work on high volume projects and the prices can’t be beat.  Usually takes 20-30 days to turn an assembly project around.  The other shop is here in town – about 15 minutes away.  Though their assembly costs are typically higher, it’s great to have partners who work in the same time zone, speak the same language, and can work really, really quickly.  They’ll regularly assembly our orders of 10-20 circuit boards – some fairly complex – in just 2 or 3 days.

It looks like the controller will be able to parse 2 consecutive universes of data (1024 channels), which roughly equates to 340 RGB nodes.

Demo video of  a handful of Tripix being driven:

Art-Net #3

Good news is that we’re now successfully receiving & parsing Art-Net packets.  Bad news is the code barfs with more than one universe at full speed (512 channels at 44 Hz) on the wire.

 Next task is to optimize some buffers and convert critical parts of the human-readable code into super-efficient machine language.  Hopefully this will dramatically increase the system throughput.

Estimates at this time is that our single controller will be able to support 5-6 universes of DMX over Art-Net at full speed.  Anyone need a crazy inexpensive Art-Net to DMX bridge?

Good times. More soon.


The Future

A challenge with point source pixels, classic pixels, Tripix and RGB emitters in general is that they require stacks and stacks of data to run properly and smoothly.  Unfortunately, a regular DMX universe contains 512 channels, which is only enough to drive 170 3-color pixels at 8 bits per color.

Last year, my personal rig required the better part of two universes.

This year, folks are running displays based our pixels and sized between 1K and 7K discretely controlled RGB emitters.  On the high end, that’s nearly 20,000 bytes of data for each ‘frame’ of a display scene.  Step that up to video playback speed (30 fps) and the datarate approaches 6 megabits per second, sustained.

Driving a rig that size with regular DMX gear costs a small fortune in cable and connectors alone.  And one of the biggest, baddest $40K lighting consoles in town, the GrandMA, tops out at about 16,000 channels.   

Enter Art-Net.

For the uninitiated, Art-Net is a totally open, freely-published, ethernet-based transport protocol for lighting control data.  It’s based on UDP packets and traverses regular (inexpensive!) ethernet switches and hubs with ease.  It can zip through the air over a wireless internet connection. Even the iPhone / iPod Touch can generate Art-Net packets.  Best of all, the potential bandwidth is massive.  

From the official spec:

A theoretical limit of 255 universes of DMX512 exists in this specification. However a simplistic data rate comparison (DMX runs at 250KBaud, 10BaseT at 10MBaud) suggests a maximum of 40 universes of DMX is the limit. Art-Net uses a simple delta transmission compression technique that will provide about 40 universes. If an installation of more than say 30 universes is contemplated, then it is necessary to use the unicast features of Art-Net II and 100BaseT or better physical layer. If this is done the number of universes limit becomes purely related to the network bandwidth.

Click here for a PDF copy of the Art-Net spec.

But how do you get data out of an ethernet cable and in to your lighting rig?  You need an ‘Art-Net to DMX Bridge.’  They typically contain an ethernet jack and between 1-8 XLR connectors (one per universe).  Lots of companies make them.  Though prices have come down a bit as the technology has matured, current pricing seems to be $200 – $250 per universe of DMX output.

For that reason, we’ve decided to design an Art-Net node that’s directly integrated with the existing Tripix controller.  We’ll bypass the discrete equipment (and cable, and connectors, and cost, and hassle) required for Art-Net–>DMX and DMX–>Tripix and drive the pixels directly.

It’s likely that the node will receive 2 universes (1024 channels) of data.  Thus, it will be trivially easy to drive ~ 340 RGB pixels from a single controller.

Even more attractive is that the network interface will only add about $16 to the parts list of the base controller.

Plus development time.

More soon!

Tripix – Controller Update

Tripix Controller

 Finally!  Some updates.

Above is the board layout for the Tripix controller.  Several copies of the design are being fabricated right now.  Included on the board are

  • High-voltage ‘buck’ type power supply (accepts AC or DC input, up to 15-50 V)
  • DIP switch for setting the system’s start address 
  • Terminals for DMX in & through, isolated DMX receive section
  • RJ45 jacks for driving strings and injecting power
  • USB jack for in-the-field firmware updates and (possible) string control 

Hope to have video clips of 16-20 pixels running various demo patterns later this weekend.

Micro Pixels – First Test

2009 RGB Micro Pixel
2009 RGB Micro Pixel

Two days ago the FedEx fairy delivered our first factory-assembled batch of Micro Pixels.

I unwrapped a handful, snapped a couple pictures, then plugged them in on the workbench.

Nothing happened.

Double checked the board layout against my schematic and the controller’s datasheet. The trusty ‘scope showed that all the signals were in their proper places.  And the control program was the same one I’d used when testing the rough system prototype a few weeks back.

Bizarre.  Potentially very expensive.

After another hour of testing, I discovered that the sample LEDs from the factory were different than the production LEDs.  Each had six pins and looked identical to the eyeball.  But a diode tester revealed that the polarity of all three LEDs was reversed 180 degrees.

+ + +
- - -


- - -
+ + +

Turns out the LED factory had switched things around but not updated the datasheet on their website.


Good that this was a test run of 100 pieces, instead of production assembly in multiples of 1500.

I used hot air to remove the three LEDs, then spun them around and re-attached.

At full power, these chips are exceptionally bright. They leave ghostly spots on my eyeballs.

Before running out of time that afternoon, I reworked three of the boards and chained them together.  Everything operated flawlessly.

I love the simplicity of this new design.

P.S.  We’ve had a suggestion for a new name for these guys:


3 LEDs, 3 Colors, price approaches the $3 range in large quantities.

What do you think?

(Note: There’s some additional discussion on the controller design in the ‘comments’ section below.  So click there to learn more.)

“Micro Pixels” – Grainy Photos of the 2009 Project

Just before shipping the order to me, the factory took a couple of ugly pictures of the new circuit boards.

It looks like the shipment of 100 boards will arrive later this week, barring problems in customs or a volcano eruption in the parcel’s flight path.

Visible are 2 x RJ45 jacks for easy daisy chaining (I found a supplier who will sell 6″ cat5 jumper cables for $0.48 each in small quantities).  The rear of the board contains 3 x wide-angle RGB LEDs wired in series.

Note the the component count of this design is significantly lower than anything we’ve done in the past.

For lack of a better name, this design has been yclept “The Micro Pixel.”

If you missed the introduction to the 2009 project, you can find it here:


More soon.

2009 RGB Pixel Project

Hard to believe that four years have passed since the first DMX RGB Pixel Project was cobbled together.

For 2009, we’re working on something completely different.  These don’t yet have a name – or even some sample photos – but here’s a sneak peak of the feature list.

  • System brightness to be halfway between the point source and a ‘classic’ big pixels.  Design uses 3 each wide-angle red, green and blue emitters.
  • Component count is *significantly* lower than any of our existing designs and 100% surface mount, which keeps the assembly robots fast & happy.
  • Boards are daisy chainable with cat5 jumpers OR hard-soldered connections, up to 255 per string, provided that +12v supply is re-injected from time to time.  Current draw remains stable at ~ 60 mA per pixel.
  • Position Agnostic!  No need to address each individual pixel.
  • Head-end controller handles all DMX massaging, addressing and color updating.
  • Working on a plastic ‘overmolded’ enclosure for a totally weatherproof system.
  • May even feature a plastic ‘jewel’ similar in size/shape to a standard C9 lamp.
  • Circuit board size is 2″ x .6″
  • Head-end controllers will be daisy-chainable using industry-standard  XLR-4 ‘Color Scroller‘ cables, which combine a shielded, twisted pair for data and a heavy gauge pair for power.  Last year’s cable harnesses (1 x cat5, 1 x 18 gauge pair) worked well but took way too long to assemble.

I’m very excited about these, actually.  The assembly shop is working on a test batch of 100 pieces, which should be delivered in a week or so.

Pictures & video clips to be posted as they’re available.  To be kept abreast of the latest developments, join the ‘Insiders Club’ at the top right corner of this screen.