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
Which Arduino for NeoPixel
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- adafruit_support_bill
- Posts: 88093
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Re: Which Arduino for NeoPixel
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.
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.
- nicklx
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- Joined: Sun Oct 26, 2014 7:11 pm
Re: Which Arduino for NeoPixel
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...?
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...?
- adafruit_support_bill
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- Joined: Sat Feb 07, 2009 10:11 am
Re: Which Arduino for NeoPixel
Which pixels are you using? Many of the boards and strips have resistors pre-installed, so it may not be necessary.
- nicklx
- Posts: 11
- Joined: Sun Oct 26, 2014 7:11 pm
Re: Which Arduino for NeoPixel
It's the new WS2812B chips. I have a 60pixels/meter black version.
- adafruit_support_bill
- Posts: 88093
- Joined: Sat Feb 07, 2009 10:11 am
Re: Which Arduino for NeoPixel
The newer strips have the resistor on the first pixel.
Please be positive and constructive with your questions and comments.