// Potentiometer is connected to GPIO 34 (Analog ADC1_CH6) 
const int potPin = 34;
const int Rref = 658;
const int Vref = 3300;

// variable for storing the potentiometer value
float potValue = 0;
float Rout = 0;

void setup() {
  Serial.begin(115200);
  delay(1000);
}

void loop() {
  // Reading potentiometer value
  potValue = analogRead(potPin);
  potValue = map(potValue, 0, 4095, 0, Vref);
  Rout = (potValue * Rref) / ((Vref / 1000) - (potValue / 1000));
  Serial.println(Rout);
  delay(500);
}