diff --git a/firmware/firmware.ino b/firmware/firmware.ino
index db47f65..2d8c58b 100644
--- a/firmware/firmware.ino
+++ b/firmware/firmware.ino
@@ -36,11 +36,10 @@ IPAddress dns        ( 192, 168,   0,   1);
 #define SCENE_NIGHTLY 2
 
 // 10 bit PWM
-#define PWM_OFF           0 // 0V
-#define PWM_MIN         640 // 15V - minimum light amount (~1%)
-#define PWM_MAX        1023 // 24V - maximum light amount (100%)
-#define PWM_INC           4 // 24V-15V = 9V range; 9V ≙ 1024/640 = 383 counts; 383/100% = 3,83 counts (1%) / % => round up 4 counts / % (~1%)
-#define BRI_TO_PWM_FACTOR 4 // 0-255 uint8_t brightness data x4 is 0 to 1024
+#define PWM_OFF              0 // 0V
+#define PWM_MIN            640 // 15V - minimum light amount (~1%)
+#define PWM_MAX           1023 // 24V - maximum light amount (100%)
+#define BRI_TO_PWM_FACTOR    4 // 24V-15V = 9V range; 9V ≙ 1024-640 = 383 counts; 383/100% = 3,83 counts (1%) / % => round up 4 counts / % (~1%)
 
 //********************************//
 
@@ -104,15 +103,17 @@ void lightEngine()
       {
         in_transition = true;
         current_bri[i] += step_level[i];
-        if ((step_level[i] > 0.0 && current_bri[i] > bri[i]) || (step_level[i] < 0.0 && current_bri[i] < bri[i]))
+        if ((step_level[i] > 0.0 && current_bri[i] > bri[i]) ||
+            (step_level[i] < 0.0 && current_bri[i] < bri[i]))
         {
           current_bri[i] = bri[i];
         }
-        analogWrite(pins[i], (int)(current_bri[i] * 4)); // TODO warum * 4?
+
+        analogWrite(pins[i], calcPWM(current_bri[i]));
       }
     } else {
 
-      if (current_bri[i] != 0 )
+      if (current_bri[i] != 0)
       {
         in_transition = true;
         current_bri[i] -= step_level[i];
@@ -120,7 +121,8 @@ void lightEngine()
         {
           current_bri[i] = 0;
         }
-        analogWrite(pins[i], (int)(current_bri[i] * 4)); // TODO warum * 4?
+
+        analogWrite(pins[i], calcPWM(current_bri[i]));
       }
     }
   }
@@ -134,6 +136,22 @@ void lightEngine()
 
 //********************************//
 
+uint16_t calcPWM(float tbri)
+{
+  uint16_t tmp_pwm = PWM_OFF;
+  if (tbri > 0.0)
+  {
+    tmp_pwm = PWM_MIN + (int)(tbri * BRI_TO_PWM_FACTOR);
+  }
+  if (tmp_pwm > PWM_MAX)
+  {
+    tmp_pwm = PWM_MAX;
+  }
+  return tmp_pwm;
+}
+
+//********************************//
+
 void read_eeprom_config()
 {
   for (uint8_t light = 0; light < LIGHTS_COUNT; light++)