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Hello,
First just let me say that I have no prior experience with coding on an Arduino. Recently I purchased an Arduino Nano (or a Chinese Knockoff, actually) and a 5M WS2812B LED strip to make some DIY Computer lights. By messing around with the examples from the Adafruit Neopixel library and the "Arduino – LEDStrip effects for NeoPixel and FastLED" post here on Tweaking4All, I was able to get a lot of effects that I liked. There was one, however, that I couldn't quite figure out.
I'd like a trail effect, much like the "Meteor Rain" effect in the aforementioned post, except I want it to restart back at the front of the strip smoothly instead of stopping at the end of the strip and then restarting again at the beginning, so that if you placed the two ends of the strip next to one another it would be a smooth loop. It would be essentially identical to the effect in this video: https://www.youtube.com/watch?v=R9wbYRV1AEM. I use the Adafruit Neopixel library, but if it's easier to do with FastLED I'd be glad to switch.
Thanks in advance. 
Hi bbitz01,
sorry for the late reply - the holidays tend to gobble up a lot of time 
So you basically want the effect to loop around?
I do not have my Arduino near me, so I'm just doing a guess here ... and this example will never leave the function
void meteorRain(byte red, byte green, byte blue, byte meteorSize, byte meteorTrailDecay, boolean meteorRandomDecay, int SpeedDelay) {
setAll(0,0,0);
int i = 0;
while(true){
// fade brightness all LEDs one step
for(int j=0; j<NUM_LEDS; j++) {
if( (!meteorRandomDecay) || (random(10)>5) ) {
fadeToBlack(j, meteorTrailDecay );
}
}
// draw meteor
for(int j = 0; j < meteorSize; j++) {
if( ( i-j <NUM_LEDS) && (i-j>=0) ) {
setPixel(i-j, red, green, blue);
}
}
showStrip();
delay(SpeedDelay);
i++;
if(i=NUM_LEDS+NUM_LEDS) { i=0; }
}
}
Like I said: I haven't tested this, and I hope I didn't make a typo 
hans,
If I put in your code correctly (which I'm not sure I did), I have this:
#include <Adafruit_NeoPixel.h>
#define PIN 3
#define NUM_LEDS 81
Adafruit_NeoPixel strip = Adafruit_NeoPixel(NUM_LEDS, PIN, NEO_GRB + NEO_KHZ800);
void setup() {
strip.begin();
strip.show(); // Initialize all pixels to 'off'
}
void loop() {
meteorRain(0xff,0xff,0xff,10, 64, true, 30);
}
void meteorRain(byte red, byte green, byte blue, byte meteorSize, byte meteorTrailDecay, boolean meteorRandomDecay, int SpeedDelay) {
setAll(0,0,0);
int i = 0;
while(true){
// fade brightness all LEDs one step
for(int j=0; j<NUM_LEDS; j++) {
if( (!meteorRandomDecay) || (random(10)>5) ) {
fadeToBlack(j, meteorTrailDecay );
}
}
// draw meteor
for(int j = 0; j < meteorSize; j++) {
if( ( i-j <NUM_LEDS) && (i-j>=0) ) {
setPixel(i-j, red, green, blue);
}
}
showStrip();
delay(SpeedDelay);
i++;
if(i=NUM_LEDS+NUM_LEDS) { i=0; }
}
}
void fadeToBlack(int ledNo, byte fadeValue) {
#ifdef ADAFRUIT_NEOPIXEL_H
// NeoPixel
uint32_t oldColor;
uint8_t r, g, b;
int value;
oldColor = strip.getPixelColor(ledNo);
r = (oldColor & 0x00ff0000UL) >> 16;
g = (oldColor & 0x0000ff00UL) >> 8;
b = (oldColor & 0x000000ffUL);
r=(r<=10)? 0 : (int) r-(r*fadeValue/256);
g=(g<=10)? 0 : (int) g-(g*fadeValue/256);
b=(b<=10)? 0 : (int) b-(b*fadeValue/256);
strip.setPixelColor(ledNo, r,g,b);
#endif
#ifndef ADAFRUIT_NEOPIXEL_H
// FastLED
leds[ledNo].fadeToBlackBy( fadeValue );
#endif
}
void showStrip() {
#ifdef ADAFRUIT_NEOPIXEL_H
// NeoPixel
strip.show();
#endif
#ifndef ADAFRUIT_NEOPIXEL_H
// FastLED
FastLED.show();
#endif
}
void setPixel(int Pixel, byte red, byte green, byte blue) {
#ifdef ADAFRUIT_NEOPIXEL_H
// NeoPixel
strip.setPixelColor(Pixel, strip.Color(red, green, blue));
#endif
#ifndef ADAFRUIT_NEOPIXEL_H
// FastLED
leds[Pixel].r = red;
leds[Pixel].g = green;
leds[Pixel].b = blue;
#endif
}
void setAll(byte red, byte green, byte blue) {
for(int i = 0; i < NUM_LEDS; i++ ) {
setPixel(i, red, green, blue);
}
showStrip();
}
Unfortunately this just lights up the first LED on my strip white. It doesn't move, fade, etc. Perhaps I've put in the code wrong?
And no need to worry about a late reply, we've all got things to do. 
I'll have to wait until I get home (on a holiday trip right now) to do some testing.
I may have overlooked something. Unfortunately, I do not have my Arduino with me to do testing 
...
Happy New Year!
hans,
Any luck with the sketch? I haven't messed with my Arduino in a while, kind of forgot about it if I'm honest. 
Hope you enjoyed your holidays.
Haha, I had forgotten about it as well ... sorry!
First of all; I'd recommend using FastLED instead of NeoPixel.
As for the code (still not able to test this myself), I think I may have found a boo-boo ... (3rd line from the bottom, added a "-1");
void meteorRain(byte red, byte green, byte blue, byte meteorSize, byte meteorTrailDecay, boolean meteorRandomDecay, int SpeedDelay) {
setAll(0,0,0);
int i = 0;
while(true){
// fade brightness all LEDs one step
for(int j=0; j<NUM_LEDS; j++) {
if( (!meteorRandomDecay) || (random(10)>5) ) {
fadeToBlack(j, meteorTrailDecay );
}
}
// draw meteor
for(int j = 0; j < meteorSize; j++) {
if( ( i-j <NUM_LEDS) && (i-j>=0) ) {
setPixel(i-j, red, green, blue);
}
}
showStrip();
delay(SpeedDelay);
i++;
if(i=NUM_LEDS+NUM_LEDS-1) { i=0; }
}
}
But even with that, I would have expected to see at least something happen. Does the strip work properly with other effects?
hans,
I'm having the same issue as last time. Using this code (with the part you wrote):
#include <Adafruit_NeoPixel.h>
#define PIN 3
#define NUM_LEDS 81
// 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(NUM_LEDS, PIN, NEO_GRB + NEO_KHZ800);
void setup() {
strip.begin();
strip.show(); // Initialize all pixels to 'off'
}
void loop() {
meteorRain(0xff,0xff,0xff,10, 64, true, 30);
}
void meteorRain(byte red, byte green, byte blue, byte meteorSize, byte meteorTrailDecay, boolean meteorRandomDecay, int SpeedDelay) {
setAll(0,0,0);
int i = 0;
while(true){
// fade brightness all LEDs one step
for(int j=0; j<NUM_LEDS; j++) {
if( (!meteorRandomDecay) || (random(10)>5) ) {
fadeToBlack(j, meteorTrailDecay );
}
}
// draw meteor
for(int j = 0; j < meteorSize; j++) {
if( ( i-j <NUM_LEDS) && (i-j>=0) ) {
setPixel(i-j, red, green, blue);
}
}
showStrip();
delay(SpeedDelay);
i++;
if(i=NUM_LEDS+NUM_LEDS-1) { i=0; }
}
}
void fadeToBlack(int ledNo, byte fadeValue) {
#ifdef ADAFRUIT_NEOPIXEL_H
// NeoPixel
uint32_t oldColor;
uint8_t r, g, b;
int value;
oldColor = strip.getPixelColor(ledNo);
r = (oldColor & 0x00ff0000UL) >> 16;
g = (oldColor & 0x0000ff00UL) >> 8;
b = (oldColor & 0x000000ffUL);
r=(r<=10)? 0 : (int) r-(r*fadeValue/256);
g=(g<=10)? 0 : (int) g-(g*fadeValue/256);
b=(b<=10)? 0 : (int) b-(b*fadeValue/256);
strip.setPixelColor(ledNo, r,g,b);
#endif
#ifndef ADAFRUIT_NEOPIXEL_H
// FastLED
leds[ledNo].fadeToBlackBy( fadeValue );
#endif
}
void showStrip() {
#ifdef ADAFRUIT_NEOPIXEL_H
// NeoPixel
strip.show();
#endif
#ifndef ADAFRUIT_NEOPIXEL_H
// FastLED
FastLED.show();
#endif
}
void setPixel(int Pixel, byte red, byte green, byte blue) {
#ifdef ADAFRUIT_NEOPIXEL_H
// NeoPixel
strip.setPixelColor(Pixel, strip.Color(red, green, blue));
#endif
#ifndef ADAFRUIT_NEOPIXEL_H
// FastLED
leds[Pixel].r = red;
leds[Pixel].g = green;
leds[Pixel].b = blue;
#endif
}
void setAll(byte red, byte green, byte blue) {
for(int i = 0; i < NUM_LEDS; i++ ) {
setPixel(i, red, green, blue);
}
showStrip();
}
I get this:
http://s61.photobucket.com/user/bbitz01/media/IMG-2406_zpsfa0jhuez.jpg .html?sort=3&o=0
That one light stays just like that and does not fade, flash, change color, move, or anything else.
The strip does work just fine with other effects. With very similar code, using the default meteor rain effect from the post mentioned earlier:
#include <Adafruit_NeoPixel.h>
#define PIN 3
#define NUM_LEDS 81
// 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(NUM_LEDS, PIN, NEO_GRB + NEO_KHZ800);
void setup() {
strip.begin();
strip.show(); // Initialize all pixels to 'off'
}
void loop() {
meteorRain(0xff,0xff,0xff,10, 64, true, 30);
}
void meteorRain(byte red, byte green, byte blue, byte meteorSize, byte meteorTrailDecay, boolean meteorRandomDecay, int SpeedDelay) {
setAll(0,0,0);
for(int i = 0; i < NUM_LEDS+NUM_LEDS; i++) {
// fade brightness all LEDs one step
for(int j=0; j<NUM_LEDS; j++) {
if( (!meteorRandomDecay) || (random(10)>5) ) {
fadeToBlack(j, meteorTrailDecay );
}
}
// draw meteor
for(int j = 0; j < meteorSize; j++) {
if( ( i-j <NUM_LEDS) && (i-j>=0) ) {
setPixel(i-j, red, green, blue);
}
}
showStrip();
delay(SpeedDelay);
}
}
void fadeToBlack(int ledNo, byte fadeValue) {
#ifdef ADAFRUIT_NEOPIXEL_H
// NeoPixel
uint32_t oldColor;
uint8_t r, g, b;
int value;
oldColor = strip.getPixelColor(ledNo);
r = (oldColor & 0x00ff0000UL) >> 16;
g = (oldColor & 0x0000ff00UL) >> 8;
b = (oldColor & 0x000000ffUL);
r=(r<=10)? 0 : (int) r-(r*fadeValue/256);
g=(g<=10)? 0 : (int) g-(g*fadeValue/256);
b=(b<=10)? 0 : (int) b-(b*fadeValue/256);
strip.setPixelColor(ledNo, r,g,b);
#endif
#ifndef ADAFRUIT_NEOPIXEL_H
// FastLED
leds[ledNo].fadeToBlackBy( fadeValue );
#endif
}
void showStrip() {
#ifdef ADAFRUIT_NEOPIXEL_H
// NeoPixel
strip.show();
#endif
#ifndef ADAFRUIT_NEOPIXEL_H
// FastLED
FastLED.show();
#endif
}
void setPixel(int Pixel, byte red, byte green, byte blue) {
#ifdef ADAFRUIT_NEOPIXEL_H
// NeoPixel
strip.setPixelColor(Pixel, strip.Color(red, green, blue));
#endif
#ifndef ADAFRUIT_NEOPIXEL_H
// FastLED
leds[Pixel].r = red;
leds[Pixel].g = green;
leds[Pixel].b = blue;
#endif
}
void setAll(byte red, byte green, byte blue) {
for(int i = 0; i < NUM_LEDS; i++ ) {
setPixel(i, red, green, blue);
}
showStrip();
}
I get this (the effect is moving around, it's just a still picture):
.html?sort=3&o=1
Perhaps I'm doing something wrong on my end? Additionally, for some reason I've never been able to get FastLED to work, don't know why. 
Thanks.
Hi bbitz01,
the link of the picture didn't work, and when I changed "http" to "https" I got a picture of PC case ... ?
Anyhoo ... we must be overlooking something simple, although I'm surprised that FastLED isn't working for you. Maybe the knock off Nano is to blame, but I kinda doubt that.
I still do not have my hardware available to test, so let's see what could be wrong with the code. I have moved around code a little to make it more readable for myself ...
This is what should work, or at least should show "something" ....
void meteorRain(byte red, byte green, byte blue, byte meteorSize, byte meteorTrailDecay, boolean meteorRandomDecay, int SpeedDelay) {
int i=0;
setAll(0,0,0);
while(true) { // was: for(int i = 0; i < NUM_LEDS+NUM_LEDS; i++) {
// fade brightness all LEDs one step
for(int j=0; j < NUM_LEDS; j++) {
if( (!meteorRandomDecay) || (random(10)>5) ) { fadeToBlack(j, meteorTrailDecay); }
}
// draw meteor
for(int j=0; j < meteorSize; j++) {
if( ( i-j < NUM_LEDS) && (i-j >= 0) )
{ setPixel(i-j, red, green, blue); }
else if (i<j)
{ setPixel(NUM_LEDS-j, red, green, blue); } // added this so it does "negative" LED positions as well
}
showStrip();
delay(SpeedDelay);
i++;
if(i>=NUM_LEDS+NUM_LEDS) { i=0; }
}
}
I'm not sure what I'm overlooking if this one doesn't work - then again, it's early in the morning here and I may need some more coffee
p.s. you can also post an image or small video a an attachment ...
For video I recommend pulling it through HandBrake to get a more efficient file size.
hans,
Yes, it is a computer case - the LED strip goes in a ring around the edge (that's why I want the effect to be a full circle instead of cutting off at the end of the strip). You can't see the strip in the first picture, but you can in the second.
Anyways, the code you posted this time did work - the effect the same as the code from the original post, I'm assuming this is what you were going for just to make sure everything works properly.
Did a bit of playing. Removed the while statement and removed the //was, so now it's just for(int i = 0; i < NUM_LEDS+NUM_LEDS; i++) {
The code is as follows:
void meteorRain(byte red, byte green, byte blue, byte meteorSize, byte meteorTrailDecay, boolean meteorRandomDecay, int SpeedDelay) {
int i=0;
setAll(0,0,0);
for(int i = 0; i < NUM_LEDS+NUM_LEDS; i++) {
// fade brightness all LEDs one step
for(int j=0; j < NUM_LEDS; j++) {
if( (!meteorRandomDecay) || (random(10)>5) ) { fadeToBlack(j, meteorTrailDecay); }
}
// draw meteor
for(int j=0; j < meteorSize; j++) {
if( ( i-j < NUM_LEDS) && (i-j >= 0) )
{ setPixel(i-j, red, green, blue); }
else if (i<j)
{ setPixel(NUM_LEDS-j, red, green, blue); } // added this so it does "negative" LED positions as well
}
showStrip();
delay(SpeedDelay);
i++;
if(i>=NUM_LEDS+NUM_LEDS) { i=0; }
}
}
Cool to see that you've gotten a little further and I'm sorry that I do not have the ability to test (at the moment).
It shouldn't be impossible to make this loop though.
One note; in your code check out these lines:
i++;
if(i>=NUM_LEDS+NUM_LEDS) { i=0; }
In your case it will keep resetting the for-loop and make it keep going and going and going ...
Under ideal circumstances we'd want the leds to be addressed even when beyond number of LEDs.
What I mean with that; if we have 10 leds, and the counter (i) is goes to the 11th led, then that 11th led should become the first led.
void meteorRain(byte red, byte green, byte blue, byte meteorSize, byte meteorTrailDecay, boolean meteorRandomDecay, int SpeedDelay) {
int i=0;
setAll(0,0,0);
for(int i = 0; i < NUM_LEDS+NUM_LEDS; i++) {
// fade brightness all LEDs one step
for(int j=0; j < NUM_LEDS; j++) {
if( (!meteorRandomDecay) || (random(10)>5) ) { fadeToBlack(j, meteorTrailDecay); }
}
// draw meteor
for(int j=0; j < meteorSize; j++) {
if( ( i-j < NUM_LEDS) && (i-j >= 0) )
{ setPixel(i-j, red, green, blue); }
else // try removing this: if (i<j)
{ setPixel(NUM_LEDS-j, red, green, blue); } // added this so it does "negative" LED positions as well
}
showStrip();
delay(SpeedDelay);
i++;
if(i>=NUM_LEDS+NUM_LEDS) { i=0; }
}
}
In the "draw meteor" section, you may want to toy with that loop.
