Coding Simultaneous Output to Neopixel and an LED

Other Hardware LEDs and Multiplexing
3

Grumpy_Mike:
You must remove all delays and for loops from your code

Not all for loops, wouldn't you agree Mike?

For example:

  for (j = 0; j < 64; j++) {
    for (i = 0; i < strip.numPixels(); i++) {
      strip.setPixelColor(i, j, 0, 0, 0);
    }
    strip.show();
    delay(15);
  }

The inner for loop is fine. The outer for loop needs to go. The fact that that the outer for loop has a delay in it is the clue to that.