LED light suit, teensy 3.0

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george-E

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Hi,

I'm making a light suit. The first variation of this will consist of approximately 550-650 led pixels equally distributed head to toe (with the exception of hands and feet).

Initial hardware spec intent:
- 5V power (NIMH battery pack(s) 10-20aH capacity)
- single teensy 3.0
- waterproof power and signal connectors
- eventually some momentary buttons, toggle switches, potentiometer tied into dimming

Setup spec:
- single array of the leds on hardware SPI (pins 11 data 13 clock)
- +5v and ground will be tapped at every 50 (perhaps every 25 pixels)

Capability:
- I’m not entirely sure… Multiple array patterns ranging from rolling rainbows (similar to those on adafruit library) to simple single color ++ floods, to segmented patterns, really "anything that looks cool"
- some POV visual effects
- human input capability (dimming, toggling between looped sequences, etc)

My pertinent level of understanding:
- good with mechanics, mild/moderate with electronics
- novice/just learning programming related to C++ library building and language

My research and purchase:
Given a lot of the ICs for the pixels seem similar in price but vary in capability, which ones, for my application would offer the highest performance and future flexibility. I have researched for weeks and still feel a little lost. I went with an order of the WS2801 primarily because of the extensive support they seemed to have. Unfortunately after my purchase I’m wondering if their data rate limitations will make me outgrow them quickly. At some point I assume a limitation on data rate would limit capability. But the "location or value" of that limitation depends on setup* (one single array, or multiple) and how coding is done and how complex and resource-intensive things get. All of these vague principles I understand, but don't specifically know how they will apply because I just don’t know enough about the code and implications on hardware resources (I think the teensy was a good upgrade to the UNO, but beyond that…?).

My question:
Should I go with another IC that offers more data rate capability given FASTSPI and OCTOWS2811 (or other libraries)? OR Should I stick with these WS2801 5v pixels but perhaps consider different setups other than a single long array or just a single teensy 3.0 board. I am concerned with refresh rates and speed. Perhaps I need to go with a chip that has protocol-based timing or built in timing?

It is not my intent to ask others to do my research for me. I’m just looking to help accelerate my learning. I’ve already looked at some of the screen projects here and elsewhere. Anything is appreciated. I've spent hours researching and doing the Google. Given my lack of knowledge on the subject, I don't fully understand how the information of parameters and specs I've found or come across, translates into meaningful performance capabilities.

Cheers,
George
 
Update to this: I realize since I'm, at this point, going for patterns and not necessarily frame-by-frame image reproduction, my frame rate requirement is relatively low compared to a video application. So for now, I'm sticking with the WS2801s I have.

If anyone has any suggestions for SPI pixel-string based LEDs that are more robust/faster than the WS2801s let me know. I know the SM16716 has a better indication of clock speed capability according to the FastSPI guys but it is also said to have a "terrible protocol." While the speed of 16Mhz is better than the WS2801s practical limit of 1Mhz, I'm not sure whether or not the "terrible protocol" is something the FastSPI guys had to deal with when making the library compatible for that chip or if it has an impact on how the chip performs relative to sketches that sit on top of the library. It may turn out the max data rate is lower than the WS2801's mbps because of an inefficient protocol. FastSPI doesn't have numbers for that chip.

The weekend project is getting the lights mounted to the clothes and securing all grounding and +5V power along appropriate places in the ~600 LED array.

Anyway, I'll keep updating this as I go. Feel free anyone to chime in with any ideas.

Cheers,
George
 
Hi Paul,

Are the LPD8806 offered in a pixel-string format that you have seen? Have you seen LPD8803 in pixel-string form? I'm assuming either would be a great v2.0 of this!

As far as Teensy 3.0 goes, would I get speed improvements by splitting up my 600 pixels into smaller arrays? Or with the WS2801 is a single array on hardware SPI the best method?

Cheers,
George
 
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