added arduino code and moved raspbi code

added arduino code is the read out of the sensor via an arduino.
the raspicode is moved to its own section.

arduino/door_status.ino

@@ -0,0 +1,66 @@
+# arduino Duemilanove
+#define IR_INPUT_PIN A0
+#define IR_LED_PIN 13
+
+#define status_red_PIN 12
+#define status_yellow_PIN 11
+#define 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);
+}
+
+
+int threshold = 900;
+int value_b4 = 900;
+
+int value = 0;
+
+void loop(){
+  int ambient = 0;
+  int lit = 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);
+  Serial.print(" ");
+  Serial.println(ambient);
+  delay(500);
+
+  if (value >= threshold) {
+    digitalWrite(status_red_PIN, HIGH);
+    digitalWrite(status_yellow_PIN, LOW);
+    digitalWrite(status_green_PIN, LOW);
+  }
+
+  //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);
+  }
+
+  value_b4 = value;
+}