diff --git a/arduino/door_status.ino b/arduino/door_status.ino
index 805043f..a6c00cb 100644
--- a/arduino/door_status.ino
+++ b/arduino/door_status.ino
@@ -1,66 +1,80 @@
-# arduino Duemilanove
-#define IR_INPUT_PIN A0
-#define IR_LED_PIN 13
+// door status on arduino
+// arduino is Duemilanove
+// sensor is a reed sensor
 
-#define status_red_PIN 12
-#define status_yellow_PIN 11
-#define status_green_PIN 10
+#define IR_INPUT_PIN 13
+
+#define space_status_red_PIN 12
+#define space_status_yellow_PIN 11
+#define space_status_green_PIN 10
 
 
 
 void setup(){
  Serial.begin(9600); 
  pinMode(IR_INPUT_PIN, INPUT);
- pinMode(IR_LED_PIN, OUTPUT);
 
- pinMode(status_red_PIN, OUTPUT);
- pinMode(status_yellow_PIN, OUTPUT);
- pinMode(status_green_PIN, OUTPUT);
+ pinMode(space_status_red_PIN, OUTPUT);
+ pinMode(space_status_yellow_PIN, OUTPUT);
+ pinMode(space_status_green_PIN, OUTPUT);
 }
 
 
-int threshold = 900;
-int value_b4 = 900;
+int threshold = 20;
+int space_status = threshold / 2;
+int space_status_b4 = 0;
+int delay_time = 1000;
 
-int value = 0;
 
 void loop(){
-  int ambient = 0;
-  int lit = 0;
+  int pin_status = 0;
   
   
-  digitalWrite(IR_LED_PIN, LOW);
-  delay(5);                            //To give ADC and LED transition time
-  ambient = analogRead(IR_INPUT_PIN);
-  
-  digitalWrite(IR_LED_PIN, HIGH);
-  delay(5);
-  lit = analogRead(IR_INPUT_PIN);
-  
-  value = ((lit - ambient) + value_b4) / 2; // small filter
-  
-  Serial.print(value);
+  pin_status = digitalRead(IR_INPUT_PIN);
   Serial.print(" ");
-  Serial.println(ambient);
-  delay(500);
+  Serial.print(space_status_b4);
+  Serial.print(" ");
+  Serial.println(space_status);
+  delay(delay_time);
+  
 
-  if (value >= threshold) {
-    digitalWrite(status_red_PIN, HIGH);
-    digitalWrite(status_yellow_PIN, LOW);
-    digitalWrite(status_green_PIN, LOW);
+  // pin check of the reed sensor and low pass filter
+  if (pin_status == 0){
+    if (space_status > 0){
+      space_status -= 1;
+    }
+  } else if (pin_status == 1){
+    if (space_status < threshold){
+      space_status += 1;
+    }
   }
 
-  //if (value < 977 && value >= 964) {
-  //  digitalWrite(status_red_PIN, LOW);
-  //  digitalWrite(status_yellow_PIN, HIGH);
-  //  digitalWrite(status_green_PIN, LOW);
-  //}
-
-  if (value < threshold) {
-    digitalWrite(status_red_PIN, LOW);
-    digitalWrite(status_yellow_PIN, LOW);
-    digitalWrite(status_green_PIN, HIGH);
+  
+  // status check if we can switch the status.
+  // low pass prevents waggling a bit
+  if (space_status >= threshold-3) {
+    // closed
+    space_status_b4 = 1;
+  } else if (space_status <= 3) {
+    // open
+    space_status_b4 = 0;
   }
 
-  value_b4 = value;
-}
+
+  // ampel / traffic light signals
+  if (space_status_b4 == 1) {
+    // closed
+    digitalWrite(space_status_red_PIN, HIGH);
+    digitalWrite(space_status_green_PIN, LOW);
+  } else if (space_status_b4 == 0) {
+    // open
+    digitalWrite(space_status_red_PIN, LOW);
+    digitalWrite(space_status_green_PIN, HIGH);
+  }
+
+  if (space_status > 3 && space_status < threshold - 3) {
+    digitalWrite(space_status_yellow_PIN, HIGH);
+  } else {
+    digitalWrite(space_status_yellow_PIN, LOW);
+  }
+}
\ No newline at end of file