Single LED Lights Up

Other Hardware LEDs and Multiplexing
1

Apparently I'm code illiterate and didn't know that the "leds[0]" referred to led number. :frowning:

I'm using a MEGA 2560 and these [url=https://www.amazon.com/gp/product/B014R5PC42/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1]strands[/url].  I've looked around and can't find fixes to my issue.

My wires are connected properly and the first LED lights up and reacts to the code for delayed color changing and the wires are connected properly the three wires coming from the arduino 5v, GND, and the 6th data pin all going into the right end of the strip directed by the arrows on the strip.

Code if it matters using FastLED:
#include <FastLED.h>
#define NUM_LEDS 150
#define DATA_PIN 6

CRGB leds[NUM_LEDS];

void setup() {
FastLED.addLeds<NEOPIXEL, DATA_PIN>(leds, NUM_LEDS);

}

void loop() {
 leds[0] = CRGB::Black; 
        FastLED.show(); 
        delay(3000); 
 leds[0] = CRGB::Blue; 
        FastLED.show(); 
        delay(1500); 
 leds[0] = CRGB::Red; 
        FastLED.show(); 
        delay(1500); 
 leds[0] = CRGB::Green; 
        FastLED.show(); 
        delay(1500); 
 leds[0] = CRGB::Pink; 
        FastLED.show(); 
        delay(1500); 
}

If I only have the data pin from the arduino connected the strip to send the code data or what not and power it from a AC/DC adapter with a ground and power wire coming from it; the entire strip lights up and changes color but none are the right color and all switch to a random colors for each of the changes.
3

If I only have the data pin from the arduino connected the strip to send the code data or what not and power it from a AC/DC adapter with a ground and power wire coming from it; the entire strip lights up and changes color but none are the right color and all switch to a random colors for each of the changes.

You need to connect the ground of the power supply to the ground of the Arduino.

If you want all the LEDs to change to the same colour then use the colour fill function of that library.