Help with coding Arduino for Adafruit Neopixels

Ok, I am on my way.

I found a piece of code on a forum that seems to (partially) do what I want.

The problem is it will work with 2 pixels but will not work with 4.

Can anyone help me with why?

I do not know why the code includes "i<strip.numPixels"

Does not seem necessary for what I am doing. I am thinking that is part of the reason why it will work with 2 but not 4 pixels.

Anyway, here is the code

void fadeOut(uint8_t wait) {
  uint16_t i, j;

  for(j=254; j>0; j--) {
    for(i=0; i<strip.numPixels(); i++) {
      strip.setBrightness(i+j);
    }
    strip.show();
    delay(wait);
  }
 blackout();
 }
  
  void blackout() {
    strip.setPixelColor(0, 0, 0, 0);
    strip.setPixelColor(1, 0, 0, 0);
    strip.setBrightness(255);
    strip.show();
  }

Ok, I am on my way.

I found a piece of code on a forum that seems to (partially) do what I want.

The problem is it will work with 2 pixels but will not work with 4.

Can anyone help me with why?

I do not know why the code includes "i<strip.numPixels"

Does not seem necessary for what I am doing. I am thinking that is part of the reason why it will work with 2 but not 4 pixels.

Anyway, here is the code

void fadeOut(uint8_t wait) {
  uint16_t i, j;

  for(j=254; j>0; j--) {
    for(i=0; i<strip.numPixels(); i++) {
      strip.setBrightness(i+j);
    }
    strip.show();
    delay(wait);
  }
 blackout();
 }
  
  void blackout() {
    strip.setPixelColor(0, 0, 0, 0);
    strip.setPixelColor(1, 0, 0, 0);
    strip.setBrightness(255);
    strip.show();
  }

what is this property being set to strip.numPixels(); as this is where the number of pixels will be set, it should be near the top of your program (Not included in the post)

Peter

The other part is that in the blackout function, it seems to be only addressing pixel 0 and 1. you can make a loop out of this or add two more lines to handle 2 and 3

I do have the number of pixels addressed in the beginning of my sketch. I used this block from the strandtest sketch from the neopixel library:

//Include Neopixel Library
#include <Adafruit_NeoPixel.h>

//Define pin for Neopixels on pin 4 on Trinket
#define PIN 4
#define SWITCH 3

//Include neopixel information
// Parameter 1 = number of pixels in strip
// Parameter 2 = pin number (most are valid)
// Parameter 3 = pixel type flags, add together as needed:
//   NEO_KHZ800  800 KHz bitstream (most NeoPixel products w/WS2812 LEDs)
//   NEO_KHZ400  400 KHz (classic 'v1' (not v2) FLORA pixels, WS2811 drivers)
//   NEO_GRB     Pixels are wired for GRB bitstream (most NeoPixel products)
//   NEO_RGB     Pixels are wired for RGB bitstream (v1 FLORA pixels, not v2)
Adafruit_NeoPixel strip = Adafruit_NeoPixel(2, PIN, NEO_GRB + NEO_KHZ800);
//I Include 2 Neopixels, I would like 4 eventually

the blackout function I plan to add 2 more lines to it when I figure out how to make the fadeOut function work with 4 pixels.

What can I replace the strip.numPixels() with in the function to make it work regardless of how many pixels I have in the strip?

well in the code you just posted, you have only declared 2 pixels, you need to have

Adafruit_NeoPixel strip = Adafruit_NeoPixel(4, PIN, NEO_GRB + NEO_KHZ800);

if you want it to work with 4 pixels

Regards

Ya, I know

The problem is when I put 4 in there the fadeOut(t) function makes everything go screwey

Either it doesn't fade at all

Sometimes it leaves the brightness set to 0 or some other random value

and it gives more of a strobe like show than a smooth fade

So what do I need to fix in the fadeOut(t)

So that it works when I set the sketch for 4 pixels?

There is a problem that I have hit before and that is having the speed set too high (800Khz vs 400Khz), for a few leds it would work but add more and would not

Have you tried setting the frequency to the lower setting

Adafruit_NeoPixel strip = Adafruit_NeoPixel(4, PIN, NEO_GRB + NEO_KHZ400);

what is the exact type of pixel   WS2812B, WS2811, WS??

I am using WS2812B I believe

They are this exact item from Adafruit:

http://www.adafruit.com/products/1312

So I believe they need to be 800kHz