#include <SPI.h>

int CS = 10;

void setup() {
  pinMode(CS, OUTPUT);
  SPI.begin();
  Serial.begin(9600);
}

void loop() {
  for (int i = 0; i < 256; i++) {
    digitalPotWrite(i);
    Serial.print("Potentiometer set to: ");
    Serial.println(i);
    delay(100);
  }
}

void digitalPotWrite(int value) {
  digitalWrite(CS, LOW);
  SPI.transfer(0);
  SPI.transfer(value);
  digitalWrite(CS, HIGH);
}