Flora or Gemma? - Accoustic Bass+Neo Pixel Strip

[DrWasabi]

Hi Folks,

I want to light up my Accoustic Upright Bass using 1 meter of 30 Neo Pixel Strip. I like the two different effects shown by the Ampli-Tie and the LED drum project.

To help with shopping for the right parts:

1. I will be playing for 1-2 hours at a time. Which lipo battery or nicad pack is recommended and how long will they last? (Chart/formula?) I don't think there will every be white light, but single and double color mixes could reach 80% brightness. Subquestion: it appears the strips run on 5v, but the batteries used in these kits are 3.7 v... So what's up?

2. Is Gemma powerful (memory and amps) enough to run this or do I need Flora? or Trinket/pro? I don't need the full bouncing effect of the ampli-tie, but for the first run I imagine some color changes based on volume, with a little more variety than the drum project . Later, if I programed colors determined by speed (BPM) or pitch, would that overload the memory space of Gemma? I've looked at the Color Organ tutorial, but wasn't sure if that is amplitude or frequency determined. Have you see this done before? I have never programed before, so I would prefer to use something in the library...

Thanks in advance for your response....

[adafruit_support_bill]

For battery life, I like to estimate conservatively. Worst-case for 30 pixels would be (30 * 60mA) = 1800mA. For 2 hours you would need (1800mA * 2h) = 3600mAh. We have a 4400mAh pack that should do the job with a bit in reserve: https://www.adafruit.com/products/354

The pixels are designed for 5v operation, but they run well enough on 3.7v. They will not be quite as bright as when operated at 5v, but unless you are playing outdoors at high-noon, they will be bright enough.

The Gemma is powerfl enough to run the Ampli-Tie code andthings of similar complexity. If you are anticipating expanding into frequency analysis or other advanced functionality, you may want a processor with a bit more horsepower. The Flora or Trinket Pro are both good choices. If you will be running the LEDs at 3.7v, be sure to use a 3.3v processor.

[DrWasabi]

Thank you for your quick response. I will order that battery.

I am now considering running two different legs of 15 leds. Ideally I would run one leg inside the bass and one leg outside the bass. Is there a way to toggle switch which one is activated using the gemma board or would this require a trinket/flora. Ideally the positions would be power-Off/A/B/A+B.

Thanks!

[adafruit_support_bill]

You could probably squeeze that onto a Gemma, but it would take all available pins.

[DrWasabi]

Great. How would I squeeze the switch and second leg onto a Gemma? Also, do you have a switch that would meet that need or do you recommend another vender

[adafruit_support_bill]

The Gemma has 3 GPIO pins. You need one for the mic and one for the strip. Adding a button would take up the third and last pin.

You could wire up any momentary pushbutton to a pin and use it to cycle through the various modes (A, B, AB, OFF).

If both strips will be displaying the same thing, just connect them to the same signal pin. No code changes required.

If you want to have them do different things, you would need to step up to a processor with more pins. And, of course, you would need to write code to drive the second strip.

[DrWasabi]

Thank you Bill for you timely responses.

Based on our conversations, I think I will get a 3.3V trinket, since it seems like i will be already bumping up against the pin limits of the gemma.

1. Does the code work equally well on the trinket for the application I describe? Any other hardware issues that would make Trinket poor choice for this portable two leg LED display with the lipo battery?

2. Does the color organ code run on volume or frequency response? (It looks like volume. In fact, some of the code looks like it's from the ampli-tie). Do you see a frequency based sketch out there?

[adafruit_support_bill]

The Trinket and Gemma have the same processor, so the same code will run on both.
Looking at the color organ code, it appears to be just volume based.
This guide does some frequency analysis via FFTs, but that would require a more powerful processor.
https://learn.adafruit.com/fft-fun-with ... transforms

[DrWasabi]

Hey Bill,

I see you are out of stock on the 3.3v trinket.

1. What's the trade off on getting the 5v on for this project?
•Battery time cut by 2/5th?
•Perhaps my mic wouldn't work with that voltage?

On the positive side I get more brightness with 5v. The LEDs in my application will be only ever be viewed as reflected off the dark wood of the bass, or illuminate the inside cavity, so they never will be directly seen. Maybe the extra brightness will help on an outdoor stage during daytime.

Buy 5v now Or better to wait? What do you think?

Thanks for your wisdom in project planning

[adafruit_support_bill]

The LEDs in my application will be only ever be viewed as reflected off the dark wood of the bass, or illuminate the inside cavity, so they never will be directly seen. Maybe the extra brightness will help on an outdoor stage during daytime.

That would be a good argument for going with 5v.

[DrWasabi]

Hi Bill,

I'm putting my burgeoning order together. You mentioned:

You could wire up any momentary pushbutton to a pin and use it to cycle through the various modes (A, B, AB, OFF).
.

1. Any suggestions where I might find code to trigger that cycle?

I'm now envisioning some manual control of the light range. When I'm playing blues, I want the the colors to oscilate more in the blue-green range. When playing rockabilly, more red-yellow range. Classical: the rainbow effect current in the color organ.

2. Is this particularly ambitious? Any suggestions where I might find code for this kind of effect?
(I'm curious if it might be result of separately code functions, or an different value for one variable or a whole color table for each of those three.)

3. Could both switching effects be achieved in the rotary encoder you sell? (it's used as a mute and volume control in the Trinket USB Volume Knob project)

Thanks for your thoughts...

[adafruit_support_bill]

I'll take the second question first:

2. Is this particularly ambitious?

It is not too ambitious overall, but with any project like this, it is better to take it one step at a time.

Follow the tutorial and get the basic parts working first. Once you have a basic working system, you will have a better idea of how it works and what it can do. Then you can start looking at how to achieve different effects and how to switch between them.

[DrWasabi]

Hi Bill,

Go my first order. Thanks for all your help.

Clarification question. Will I be able to run the 5v trinket off the Lipo batteries we discussed/purchased?https://www.adafruit.com/products/354

Any tricks with that?

Thanks,

Jeff

[adafruit_support_bill]

Technically, it is overclocking. (The main difference between the 3.3v and 5v version is the clock-speed). Atmel doesn't guarantee that the processors will run at that speed on 3.3v, but in our experience, most of them do.