This turns all 8 on at once, and off at once

Neopixel stick, all on and off, basic

#include <Adafruit_NeoPixel.h>
#ifdef __AVR__
  #include <avr/power.h>
#endif

//what's the info pin?
#define PIN            6

// How many NeoPixels are attached to the Arduino?
#define NUMPIXELS      8

// When we setup the NeoPixel library, we tell it how many pixels, and which pin to use to send signals.
// Note that for older NeoPixel strips you might need to change the third parameter--see the strandtest
// example for more information on possible values.
Adafruit_NeoPixel pixels = Adafruit_NeoPixel(NUMPIXELS, PIN, NEO_GRB + NEO_KHZ800);

int delayval = 500; // delay for half a second

void setup() {
   pixels.begin(); // This initializes the NeoPixel library.
}

void loop() {

pixels.setPixelColor(0, pixels.Color(50,0,50));
pixels.setPixelColor(1, pixels.Color(50,0,50));
pixels.setPixelColor(2, pixels.Color(50,0,50));
pixels.setPixelColor(3, pixels.Color(50,0,50));
pixels.setPixelColor(4, pixels.Color(50,0,50));
pixels.setPixelColor(5, pixels.Color(50,0,50));
pixels.setPixelColor(6, pixels.Color(50,0,50));
pixels.setPixelColor(7, pixels.Color(50,0,50));
pixels.show();
delay(500);

pixels.setPixelColor(0, pixels.Color(0,0,0));
pixels.setPixelColor(1, pixels.Color(0,0,0));
pixels.setPixelColor(2, pixels.Color(0,0,0));
pixels.setPixelColor(3, pixels.Color(0,0,0));
pixels.setPixelColor(4, pixels.Color(0,0,0));
pixels.setPixelColor(5, pixels.Color(0,0,0));
pixels.setPixelColor(6, pixels.Color(0,0,0));
pixels.setPixelColor(7, pixels.Color(0,0,0));
pixels.show();
delay(500);
 
}