diff --git a/include/controller.h b/include/controller.h
new file mode 100644
index 0000000..c5099a2
--- /dev/null
+++ b/include/controller.h
@@ -0,0 +1,17 @@
+/**
+ * @file controller.h
+ * @author Ollo
+ * @brief 
+ * @version 0.1
+ * @date 2024-11-28
+ * 
+ * @copyright Copyright (c) 2024
+ * 
+ */
+#ifndef FANLEDCTL_PINS
+#define FANLEDCTL_PINS
+
+#define FAN_PIN 12
+#define SIGNAL_PIN 13
+
+#endif /* End FANLEDCTL_PINS */
\ No newline at end of file
diff --git a/src/main.cpp b/src/main.cpp
index cb9fbba..f2554ae 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -1,18 +1,80 @@
 #include <Arduino.h>
+#include "controller.h"
 
-// put function declarations here:
-int myFunction(int, int);
 
+#define DELAY_TIME 10000 // time between measurements [ms]
+#define MIN_FAN_SPEED_PERCENT 24 // minimum fan speed [%]
+#define MIN_TEMP 25 // turn fan off below [deg C]
+#define MAX_TEMP 40 // turn fan to full speed above [deg C]
+
+/**
+ * @brief Called once at start
+ * Initialize hardware pins
+ */
 void setup() {
-  // put your setup code here, to run once:
-  int result = myFunction(2, 3);
+
+  Serial.begin(115200);
+
+  pinMode(FAN_PIN, OUTPUT);
+  pinMode(SIGNAL_PIN, INPUT);
 }
 
+/**
+ * @brief Get the Fan Speed in round per minutes
+ * 
+ * @return int 
+ */
+int getFanSpeedRpm() {
+  int highTime = pulseIn(SIGNAL_PIN, HIGH);
+  int lowTime = pulseIn(SIGNAL_PIN, LOW);
+  int period = highTime + lowTime;
+  if (period == 0) {
+    return 0;
+  }
+  float freq = 1000000.0 / (float)period;
+  return (freq * 60.0) / 2.0; // two cycles per revolution
+}
+
+/**
+ * @brief Set the Fan Speed
+ * 
+ * @param p expected percentage
+ */
+void setFanSpeedPercent(int p) {
+  int value = (p / 100.0) * 255;
+  analogWrite(FAN_PIN, value);
+}
+
+/**
+ * @brief Endless loop
+ * (is called as fast as possible)
+ */
 void loop() {
-  // put your main code here, to run repeatedly:
-}
+  float temp = /* FIXME bme.readTemperature(); */ 
+  Serial.print("Temperature is ");
+  Serial.print(temp);
+  Serial.println(" deg C");
 
-// put function definitions here:
-int myFunction(int x, int y) {
-  return x + y;
-}
\ No newline at end of file
+  int fanSpeedPercent, actualFanSpeedRpm;
+
+  if (temp < MIN_TEMP) {
+    fanSpeedPercent = 0;
+  } else if (temp > MAX_TEMP) {
+    fanSpeedPercent = 100;
+  } else {
+    fanSpeedPercent = (100 - MIN_FAN_SPEED_PERCENT) * (temp - MIN_TEMP) / (MAX_TEMP - MIN_TEMP) + MIN_FAN_SPEED_PERCENT;
+  }
+
+  Serial.print("Setting fan speed to ");
+  Serial.print(fanSpeedPercent);
+  Serial.println(" %");
+  setFanSpeedPercent(fanSpeedPercent);
+
+  actualFanSpeedRpm = getFanSpeedRpm();
+  Serial.print("Fan speed is ");
+  Serial.print(actualFanSpeedRpm);
+  Serial.println(" RPM");
+
+  Serial.println();
+  delay(DELAY_TIME);
+}