(sorry the late reply - I'm traveling at the moment)

You're welcome - I had some time on my hands 😊 

You will not able to fix this in code.

Keep in mind: each of the white little squares on the strip contain a controller, and 3 LEDs (one for red, green and blue).

When all the data is send to the strip, data for all 12 leds will arrive at #1.
The controller of #1 will remove the first data block and set the the 3 leds of that LED block, since they were intended for #1 anyway.
After that controller #1 passes the remaining 11 data blocks to the 2nd led block.

The led controller of #2 will do the same thing: remove the first data block, set the leds, and pass on the remaining data (10 data blocks) and pass it on to #3, etc.

So the speed in which this happens, is your limiting factor. So this part is something we cannot really influence that much.

Now when putting 2 smaller strips in parallel, you'd actually get the exact same speed (theoretically anyway).

Hello @hans, with regards to this discussion, you correctly mentioned one of the downside's of the WS2812 is the time needed to pass the data along the chain.
All of the data for each of the three colours in each LED is written serially, in sequence, along a single data line, which means that there is a finite time between each LED along the string receiving it's command and updating. For long strings of LEDs that can become noticeable, however, it takes a very long string.

Earlier in this topic you quoted this information from the FastLED documentation:

WS2812 strips are slow for writing data, with a data rate of just 800khz, it takes 30µs to write out a single led's worth of data.

Link: https://github.com/FastLED/FastLED/wiki/Parallel-Output

In electronics terms, 30us (that's microseconds, or 1/1,000,000 second) is certainly not fast, but it's pretty instantaneous in terms of human perception (I remember reading somewhere that human perception is limited to ~10ms).
Based on this timing, if you were to use a string of 1,000 LEDs, the time between the first LED and last LED receiving their commands would be ~30ms (30/1,000 seconds, or 0.03s). If you were watching these LEDs very carefully, you might be able to see this delay, but it will still appear to be very fast.

So, your comments above are correct, but the effects only become perceptible to most users once you begin to create very long strings. If you are only creating strings of a few hundred LEDs, this affect should never be noticed.

Thanks,
David

void loop() {

colorWipe(0xe9, 0xe9, 0xe9, 200);

}

is there a way to get rid of it?

for (int i = 0; i < (NUM_LEDS / 2); ++i) {
  leds=leds = CRGB(red, green, blue);
  FastLED.show();
  delay(SpeedDelay);
}

for (int i = 0; i < (NUM_LEDS / 2); ++i) {
  leds=leds = CRGB(0, 0, 0);
  FastLED.show();
  delay(SpeedDelay);
}

The "FastLED.clear()" blanks them all, so you'd want to remove that line.

Selecting an effect based on what button has been pressed could be done with something like this (use "#define buttonPin1 10" to define the pins used for the buttons):

void setup() {
  // set pins to be able to read an inpiut
  pinMode(buttonPin1, INPUT);
  pinMode(buttonPin2, INPUT);
  pinMode(buttonPin3, INPUT);
}

void loop() {
  int button1State = digitalRead(buttonPin1);
  int button2State = digitalRead(buttonPin2);
  int button3State = digitalRead(buttonPin3);

  if (button1State == HIGH) {
  // start effect 1
  } else if (button2State == HIGH) {
  // start effect 2
  } else if (button3State == HIGH) {
  // start effect 3
  }

...

}

Note that this approach could come with little issues - for example when multiple buttons were pressed.
More details on reading buttons: Arduino - Button.

I need your help again

I want to make few chnages to the code

1- the leds are currently turing on from outside to center and suddenly turn off. I want them to turn of in same sequence.

turn on from out to center then turn off from out to center

2- I want to be able to add multipe effects in my code by reading diffrent digital pin

for exmple if pin 10 = High then turn on lead from 0 to 11 and if pin== High then turn on LED 11 to 1  ( imagine these effects are going to be used in car turn signal )

Thanks

bits me

My brother who is a software engineer told me do it this way.

He said C language is a bit different. this is going to be sequence in which the LEDs will turn on

0 and 11

1 and 10

2 and 9

.

.

.

. 

in previous code the there was a confusion on what the program should do with number LED of 12 in the formula, or something like that.

Here is the whole code for your reference:

#include "FastLED.h"

#define NUM_LEDS 12
#define PIN 7

CRGB leds;

void setup() {
FastLED.addLeds<WS2812, PIN, GRB>(leds, NUM_LEDS).setCorrection( TypicalLEDStrip );
}

void loop() {
colorWipe(0xe9, 0xe9, 0xe9, 150);
colorWipe(0x00, 0x00, 0x00, 150);
}

void colorWipe(byte red, byte green, byte blue, int SpeedDelay) {

FastLED.clear();

for (int i = 0; i < (NUM_LEDS / 2); ++i) {
leds=leds = CRGB(red, green, blue);
FastLED.show();
delay(SpeedDelay);
}

FastLED.clear(); // alternative: fill_solid(leds, NUM_LEDS, CRGB(0,0,0));
FastLED.show();
}

Thanks again

In my code I made a calculation mistake in this section:

leds          = CRGB(red, green, blue);
leds = CRGB(red, green, blue);

See, the leds are counted as such (0,1,2,3,4,5,6): 

0 and 12 (12-0 = 12, which is 1 too many)
1 and 11 (12-1)
2 and 10 (12-2)
3 and 9 (12-3)
4 and 8 (12-4)
5 and 7 (12-5)
6 and 6 (12-6)

This however should have been (0,1,2,3,4,5):

0 and 11 (to get 11: 12-1)
1 and 10 (12-2)
2 and 9 (12-3)
3 and 8 (12-4)
4 and 7 (12-5)
5 and 6 (12-6)

So the counter went to far as well both sides counted out of pace.

 👍  Your solution fixed that! Excellent find! 👍 

Just for completeness, my own code corrected:

#include "FastLED.h"

#define NUM_LEDS 12
#define PIN 7

CRGB leds;

void setup() {
  FastLED.addLeds<WS2812, PIN, GRB>(leds, NUM_LEDS).setCorrection( TypicalLEDStrip );
}

void loop() {
  colorWipe(0xe9, 0xe9, 0xe9, 150);
}

void colorWipe(byte red, byte green, byte blue, int SpeedDelay) {

  FastLED.clear();

  for (int i = 0; i < (NUM_LEDS / 2); i++) {
    leds = CRGB(red, green, blue);
    leds = CRGB(red, green, blue);
    FastLED.show();
    delay(SpeedDelay);
  }

  FastLED.clear(); // alternative: fill_solid(leds, NUM_LEDS, CRGB(0,0,0));
  FastLED.show();
}