General build platform advice

[jeromieclark]

Hi!

What I'm stuck on:

I'm looking for advice on an optimal set of microcontrollers and drivers for an addressable DotStar LED string. In terms of preference, a pre-manufactured "shield" is probably going to be more durable than a breadboard, and I intend to build something portable that would probably bounce around in my backpack.

Background & Skillset:

I'm struggling at the moment to map the existing tutorials I found to this particular application. I'm hoping to get a little advice on what micro-controller platform and accessory choices might best facilitate what I'm trying to do.

I'm really looking forward to the learning curve, but I want to make sure I'm building from an adequate foundation to get a successful result.

The Goal:

I scored this sweet cream-colored 1960s fiberglass Sousaphone at a garage sale. While I'd love to put propane effects on it, melting fiberglass above my head seems like a terrible idea. Sadly, actual fire is out, so we're on to addressable LED strips as my second-favorite source of glowy goodness.

I'd love to build an animated LED display into the bell by adhering the strip with double-sided tape, and then piping programmatic data and and/or video (as an easy-mode source for random pixel data) at the array. Ideally, I'd want to be able to define a number of sequences and use a microphone, accelerometer, or maybe touch capacitance to trigger them.

Constraints and Assumptions:

(I'm just thinking out loud, but would love validation on my assumptions)

It seems like Dotstar is the way to go since I'll be moving around and would like to avoid the nauseating slow refresh trails to the extent possible.

It would be ideal if Electronics and Power comfortably fit in a medium compartment in a day pack, and ideally accommodate a 2-4 hour runtime at a reasonably low per-LED duty cycle.

I can definitely lean on chasing effects to minimize the number of LEDs that are on simultaneously. I imagine that my animation choices are the primary knob for managing battery longevity. It looks like there are off-the-shelf 20Ah USB power banks with 5A/1A output (2.4A if I can convince it I'm a USB2 device), and I could easily carry a couple.

Thanks a lot!

[adafruit_support_bill]

You might want to take a look at this LED/Sousaphone project: viewtopic.php?f=47&t=97155&p=490134

[jeromieclark]

Thanks for the quick reply, that's a pretty cute project. From an art direction perspective, I like the idea of playing with the depth of the bell instead of using it as a 2D surface, but it's definitely achieving sufficient glow. He didn't talk much about the hardware, but I was hoping to get smoother effects when doing pwm dimming and stuff.

The bit that I'm having trouble getting my head around was that the neopixel and dotstar strings seem to have significantly different requirements for driving them, and I wasn't sure what the optimal hardware might be for(in terms of performance/optimal framerates, flexibility, etc) for driving a couple hundred pixels with satisfying performance in portable application.

In essence, would I be better off using an Arduino, or something like an AdaFruit Feather, Raspberry Pi (and/or does one have more better library/tooling support that might help me get something "cool" as I work through the learning curve)? Is there one platform that might have a shield/header/etc. that plays nicely with the dotstar strings?

[adafruit_support_bill]

Whether you go dotstars or neopixels, there isn't much that a shield could do for you. Both types of pixels are simply driven from GPIO pins. Neopixels require 1 pin, Dotstars require two. The libraries used to code them are almost identical.

The only most significant differences in driving them is that Dotstar timing is not as critical as Neopixels, so you can get away with using a non-realtime platform like a Raspberry Pi.

I'd start by looking through the Learning System tutorials and try to find a project with effects similar to the ones you are looking for, then look at what they used to drive them. You will find that the majority are driven with Arudino or compatible processors.