Supplying power to an 5V LED strip

Question

I'm working on a project to create an infinity mirror based on an Instructables tutorial. Instead of the larger analogue LED strip that the author uses, I opted for a shorter addressable LED strip that runs on 5V.

I thought I would be able to run it off the 5V port on the Arduino, but that seems not to be the case. I understand that the strip can draw up to 3.3A and the Arduino can only supply ~0.5A, but I thought it would work fine if I only turned a few lights on (each one draws ~0.05A). However many lights I program the Arduino to turn on, I always see ~10 random lights with a bias towards red.

The fact that the lights are usually red and there are ~10 of them working at any one is evidence that it is a power issue (because red is lower power and 10×0.05A = 0.5A).

Does anyone have any ideas how I can either

1. turn on only a chosen subset of lights at one time, or
2. supply the appropriate power to the LEDs (preferably from a battery) ?

---

Here's the code I'm using below, on the chance I made some stupid mistake:

/* LedStripGradient: Example Arduino sketch that shows
 * how to control an Addressable RGB LED Strip from Pololu.
 *
 * To use this, you will need to plug an Addressable RGB LED strip from Pololu
 * into pin 12.  After uploading the sketch, you should see a pattern on the LED
 * strip that fades from green to pink and also moves along the strip. */

#include <PololuLedStrip.h>

// Create an ledStrip object and specify the pin it will use.
PololuLedStrip<12> ledStrip;

// Create a buffer for holding the colors (4 bytes per color).
#define LED_COUNT 72
rgb_color colors[LED_COUNT];

void setup() {
}

void loop() {
  // Update the colors.
  byte time = millis() >> 2;
  for(uint16_t i = 0; i < LED_COUNT; i++)
  {
    byte x = time - 8*i;
    // colors[i] = (rgb_color){ x, 255 - x, x };
    colors[i] = (rgb_color){ 0, 0, 0 };
  }
  colors[0] = (rgb_color){ 0, 0, 255 };
  colors[1] = (rgb_color){ 0, 255, 0 };
  colors[2] = (rgb_color){ 255, 0, 0 };

  // Write the colors to the LED strip.
  ledStrip.write(colors, LED_COUNT);

  delay(100);
}

Thanks!

Answer 1

While it's not possible to turn all the LEDs on max brightness without extra power, the main problem was that I hadn't realized that Pololu sells 2 almost identical 0.5m LED strips, and I was reading the instructions for the other variant.

Now that I'm sending instructions using the correct protocol everything works fine as long as I limit the number of LEDs I turn on.

Sorry for the mistake.