Christmas Lights 2016

img_20161016_165807391Last year I mounted two strings of “LED Meteor Shower” (total 16x tubes) in a radial fashion on an old bicycle wheel. The effect as the individual tubes went out of sync was quite interesting and gave a nice firework/star burst pattern effect.

This year I have plans to make something similar but using Neopixels/WS2812 RGB LEDs.

I’ve made a test string consisting of 10x WS2812 LEDs, this will be one arm of the new star effect and I’d parallel up another 5-7 strings to make 6/8 in total (depending upon what is in the bank account).

I didn’t want to use an Arduino/Raspberry Pi but still wanted something that was free running – but with a degree of randomness. Hopefully with 4-5 of these stars ir would look quite good. I had planned to use FPGA/CPLD and design a WS2812 driver in VHDL but couldn’t easily find a component/development solution to meet my budget. Instead I looked again at using the Microchip PIC range to drive the WS2812 directly. Bit-Banging was out of the question as I wanted an intelligent product that had processing time available to calculate the patterns. I then found a Microchip Tec sheet AN1606 that detailed using the Configurable Logic Cells (CLCs) of their newer PIC devices. That worked well and was fairly easy to implement into a PIC16F1509 DIP device (running at 16MHz and programmed in C using the XC8 compiler).

However, delays in processing (the C overheads) caused some issues with stability. I instead decided to write the entire program in assembler. This has gone well and I now have a single strand running. There is a feed in pattern that is used to generate the LED colour/brightness in the centre, this pattern is stepped through in time. Each LED colour is automatically passed to the next LED but after it is modified to ensure it fades (just like a firework would). The time delay as the pattern steps through is also slowed as time progresses to give a more realistic slow down.

Version 1.02 can be found on my Github page Github StarBurst

I now need to:

  • Design a PCB
  • Buy components (PIC, Neopixels)
  • Buy some clear tubing to mount the WS2812 into
  • Consider controlling them with RF (868MHz) – in a similar way to the Xyloband

I’ll keep posting and will upload code/diagrams etc as I generate them. Please let me know if you enjoyed reading or wish me to explain anything further.


3 thoughts on “Christmas Lights 2016

  1. Wow sounds like you are doing some amazing things. I just found your blog today. My Christmas light installation company recently started making motifs and we are looking at doing some displays with pixel lighting as it looks like you can get pixels dirt cheap. Are the neo pixels just pixel lighting that just already assembled and “stiffer” for lack of a better term? These are easier to use than say buying a huge strip and cutting it to the length you want? Thanks for sharing, can’t wait to look through some more of your blog.

    Liked by 1 person

    • ChristmasGuys,

      Thank you for your enthusiastic email, I’m pleased you like my blogsite. I’ve spent so many years reading other people’s intersting articles that I thought I should start to share something back – although my blogsite is quite a mixture of my interests the underlying theme is that I try to do everything for as little money as possible.

      For that reason I didn’t want to pay out a lot of money for the Neopixel style strings of lights – plus there is not a huge choice of these in the United Kingdom (even on Ebay). I found the individual Neopixel type units were available as a ‘sheet’ of 100x interconnected PCBs – you can see these in one of my photos. The LED PCBs are easy to snap apart and each has tinned solder pads on the rear. Search Ebay and WS2812 and 100 pcs. These individual LED PCBs suited me as I was after making a bespoke unit and I didn’t want a lot of spare cable or to be constrained by the distance between pixels. However, making the units up like this was very tedious and time consuming. I would image that, as a buisiness, you would be better off using the pre-wired chains of 50x Neopixels or the RGB tapes. I think Neopixels are a trademarked version of the WS2812 RGB LEDs that are sold by Sparkfun – perhaps they ensure the parameters fall within a certain specification (such as brightness of each colour). The Neopixel package seems to be available in a variety of configurations – on flexible tape, wired as bullets with interconneting wires and on a PCB as a small strip or in a ring etc.

      I hope that helps you a bit more but feel free to get in contact for further explaination; you can also use my email that is under ‘contact details’ if that is easier.




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