#define VOLUME_PIN  12
#define RED_LED     23
#define GREEN_LED   19

void setup() {
  // LED接続ピン出力設定
  pinMode(RED_LED, OUTPUT);
  pinMode(GREEN_LED, OUTPUT);
}

void loop() {
  // 抵抗値読み取り
  int sensor_value = analogRead(VOLUME_PIN);

  // 4ビット分解能でPWM出力
  analogWriteResolution(RED_LED, 4);
  analogWrite(RED_LED, map(sensor_value, 0, 4095, 0, 15));

  // 8ビット分解能でPWM出力
  analogWriteResolution(GREEN_LED, 8);
  analogWrite(GREEN_LED, map(sensor_value, 0, 4095, 0, 255));

  // 時間待ち
  delay(100);
}