   const int kCommandSetDutycycle = 1;
   const int kCommandSetDefaultDutycycle = 2;
   
-  unsigned int rpm0, rpm1, rpm2;
+  unsigned int rpm0, rpm1, rpm2, rpm3;
 
   rpm0 = ReadRpm(kFan0RpmPin);
   rpm1 = ReadRpm(kFan1RpmPin);
   rpm2 = ReadRpm(kFan2RpmPin);
+  rpm3 = ReadRpm(kFan3RpmPin);
       
   Serial.print(rpm0);
   Serial.print(",");

const int kFan0PwmPin = 3;
const int kFan1PwmPin = 9;
const int kFan2PwmPin = 10;

const int kFan0RpmPin = 4;
const int kFan1RpmPin = 6;
const int kFan2RpmPin = 7;

void setup() {
  Serial.begin(19200);

  analogWrite(kFan0PwmPin, map(fan_0_dutycycle,0,100,0,255));
  analogWrite(kFan1PwmPin, map(fan_1_dutycycle,0,100,0,255));
  analogWrite(kFan2PwmPin, map(fan_2_dutycycle,0,100,0,255));
  analogWrite(kFan3PwmPin, map(fan_3_dutycycle,0,100,0,255));

  delay(200);
}
