Circuit

Schematic view

Illustration view

TinkerCad project : https://www.tinkercad.com/things/gtjDmncLAZv-copy-of-documentation-potentiometer/

Code

//----------------LIBRARIES----------------
// adafruit neopixel library
// find out more about library here: <https://adafruit.github.io/Adafruit_NeoPixel/html/class_adafruit___neo_pixel.html>
#include <Adafruit_NeoPixel.h>

//------------------WIRING------------------
// 5V -> 3.3V or 5V
// GND -> GND
// DI -> Digital pin 
#define LED_PIN  2

// 5V -> 3.3V or 5V
// GND -> GND
// DI -> Digital pin 
#define POT_PIN  A0

//----------------VARIABLES----------------
// number of LEDs
#define LED_COUNT  12
// NeoPixel luminosity, 0 (min) to 255 (max)
#define BRIGHTNESS 20

// store POT value
int potValue = 0;

// --------- OBJECTS DECLARATION ----------
// Declare neopixel Ring
Adafruit_NeoPixel ring(LED_COUNT, LED_PIN, NEO_GRB + NEO_KHZ800);
// Argument 1 = number of led
// Argument 2 = Pin
// Argument 3 = Pixel type

//This is how to declare var using RGB space for led ring
uint32_t red = ring.Color(255, 0, 0);
uint32_t purple = ring.Color(130, 0, 180);
uint32_t lightBlue = ring.Color(30, 30, 150);

void setup() {

  // Start serial communication
  Serial.begin(9600);
  
  // INITIALIZE NeoPixel ring object (REQUIRED)
  ring.begin();   
 
  // Set BRIGHTNESS to about 1/10 (max = 255)
  ring.setBrightness(BRIGHTNESS); 

}

void loop() {

  // Set all pixel colors to 'off'
  ring.clear();

  // Read potentiometer and store value in var
  potValue = analogRead(POT_PIN);
  // Map the value on led ring scale (from 0 -> 1000 to 0 -> 12)
  potValue = map(potValue, 0, 1000, 0, ring.numPixels());

  // Serial print potentiometer value 
  Serial.print("Pot value mapped is :");
  Serial.println(potValue);

  // Set Led color depending on potentiometer value
  for(int i = 0; i < potValue; i++){
    ring.setPixelColor(i, red);    
  }

  // Switch on the ring led
  ring.show();
  delay(300);
}