NeoPixel Corner Cases – accurate and easy rectangles with WS2812B strips

NeoPixel strips are great when all you want to do is go in a straight line, but what about when you want to make a turn?

Here is a simple little board that makes it easy and keeps perfect spacing on both axes.

NeoCorner

This one is laid out for 60 pixel/meter strips, but could be adjusted for other pitches.

All of the traces have 1/32″ clearance, so you can cut a bunch of them on a CNC milling machine in one pass.

DSC08908

OtherMill Porn

By luck, one-sided FR1 board happens to be about the same thickness as 3M 1/2″ foam tape, so you can run the tape up to the board and everything comes out flat.

2015-09-12 12.25.15

Full gerbers and diptrace files here…

https://github.com/bigjosh/NeoPixel-Corner-Board

The diptrace files include footprints and components for the chip and a footprint for the edge connections.

WS2812 Chip Component

WS2812 Edge Connector Component

Strips to Chips

If you have a hot air station you can easily pop a chip off a strip by holding it over ~320C air for about 3 seconds and then grabbing it with a tweezers.

DSC08907

Power and Data

If you are making a full rectangle, you can neatly inject power and data  by soldering a connector to the back of the strip and then punching a hole though the Data Out line after the last chip in the loop. I used a leather punch. 2015-09-12 13.14.37

This works especially well because the power now flows down both sides of the rectangle at the same time. Because there are now two paths for the power to get to the farthest point, you can make things twice as large compared to a rectangle where the current flows linearly around the loop.

2015-09-12 12.25.36-2

Note that the wires I used were a little thicker than the foam tape so I had to drill a hole behind them to keep everything flat.

Why DipTrace?

Listen, I know everyone loves Eagle, but I find it physically painful to use.

KiCad has some very nice features (especially interactive routing… but only if you know to switch graphics modes! WTF?) , but after wasting an hour trying to do this stupid little board I gave up and switched to DipTrace and got it done in 10 minutes.

Sadly, they don’t seem to be updating it much anymore. I don’t blame them – it is hard to compete on the low end with all the crappy-but-free PCB software out there. Still, if you are…

  1. on Windows
  2. hate Eagle
  3. just want to get your board done
  4. don’t care about people heckling you

…then give Diptrace a try. It is not perfect, but it is a pleasure to use and you can be productive and get real work done less than an hour after installing it.

6 comments

  1. Kevin Wilson

    More good info, thanks. I have been watching a lot of your project and trying to apply lessons learned to mine… I am trying to do a large cofferred ceiling lit with about 1100 APA102 (Dotstar) pixels. I have a software background and I pretty much have that covered. I am very weak in electronics however so I am not sure how to wire up that many leds in a single strip. I saw your long neopixel setup and that gave me hope! So I was initially thinking for my case I would run with a bunch of 10A power supplies every 2 meters or so… but make the ground, clock and data continuous through the whole run. but that seemed wrong for the ground so then I wondered if I should tap the ground run to ground of each power supply. Then I wondered if I should just break the ground at each supply and assume the house ground (for that circuit) would take care of each segment of the strip.

    anyway, if you can point me to a good reference on this or let me know your thoughts I would appreciate it. I want to do this right…. 70A at 5V sounds scary!

    thanks!

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