Which Arduino for NeoPixel

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nicklx
 
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Which Arduino for NeoPixel

Post by nicklx »

I'm planning on making a "word clock". I've decided to use the NeoPixel RGB strip with 60 per metre because it's addressable which makes life extremely easy. Although I'd ideally have white, I'm sure I can make it look more interesting with some colour mixing.

I have a few questions:

1) How many LEDs can be driven with a single data output from an Arduino?

2) I plan on running a power supply in parallel to 10x strips of 11 LEDs. Do I need to put a capacitor at the beginning of each strip or just across the incoming PWR/GND?

3) I'm trying to make the footprint as small as possible. The Arduino Mini seems to be exactly the same as the Arduino Uno just without the easy USB connection. Will this work for 100 LEDs?

4) Looking at the matrix (https://www.adafruit.com/products/1487) and the strip there seems to be a component (either resistor or capacitor) before each LED. What is that for and do I need something similar?

Thanks

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adafruit_support_bill
 
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Re: Which Arduino for NeoPixel

Post by adafruit_support_bill »

1) Each pixel requires 3 bytes of SRAM memory. Depending on the SRAM requirements of the rest of your code, several hundred pixels are achievable.
2) one capacitor across the main power supply should be sufficient.
3) The Mini uses the same processor, so the SRAM resources are the same as well: 2048 bytes total.
4) There are small capacitors for each led to smooth the power demands. And a resistor in series with the signal wire for impedance matching. We have found these to improve the reliability of the strips.

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nicklx
 
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Re: Which Arduino for NeoPixel

Post by nicklx »

Having a weird problem.

I have one pixel connected to an Arduino Uno. The pixel is being powered by the Arduino (and therefore the USB of the PC). When I use a 390OHM resistor in between the Arduino pin and the data in of the pixel the output isn't correct and the colour is very dim. When I remove the resistor the pixel works fine. What's happening...?

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Re: Which Arduino for NeoPixel

Post by adafruit_support_bill »

Which pixels are you using? Many of the boards and strips have resistors pre-installed, so it may not be necessary.

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nicklx
 
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Re: Which Arduino for NeoPixel

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It's the new WS2812B chips. I have a 60pixels/meter black version.

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Re: Which Arduino for NeoPixel

Post by adafruit_support_bill »

The newer strips have the resistor on the first pixel.

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