WS2811 12v LED Strip not working correctly after 69 pixels FASTLED

Hi,

I work on a project and I have to use WS2811 12v LED Strips. When I upload my code to my teensy 3.2, everything is working fine when my number of leds is under 69. I am using FastLed Library. The moment I put 70 the whole strip light up. The lenght of the strip is 100 pixels (100 groups of 3 leds). This is my code :

#include <FastLED.h>

#define NUM_LEDS 70
#define DATA_PIN 10

CRGB leds[NUM_LEDS];

void setup() { 
   
     FastLED.addLeds<WS2811, DATA_PIN, BRG>(leds, NUM_LEDS);
     FastLED.setBrightness(55);
}

void loop() {
        for(int dot = 0; dot < NUM_LEDS; dot++) { 
            leds[dot] = 0xFF8C00;
            FastLED.show();
           
        }
    }

My current setup use :

  • Teensy 3.2 power by USB
  • Power supply 12v 2A

The strip is power direct by the power supply and the ground of the strip is also attached to the ground of the teensy.

Is there so important features that are missing in my code. I dont understand why after a certain amount of leds the whole strip lights up.

Thank you
LP

Why is there a "greater" sign (">") after "BRG"?

Why is FastLED.show(); inside the loop?

Too much load on the power supply. Seventy pixels (210 LEDs) at full brightness and fully on would be 4.2 amps, you are running lower brightness and some LEDs off, but still likely at the 2 amp capacity of the power supply.