diff --git a/libraries/Tiny/Tiny.h b/libraries/Tiny/Tiny.h
index 77aeef2..93fc239 100644
--- a/libraries/Tiny/Tiny.h
+++ b/libraries/Tiny/Tiny.h
@@ -2,3 +2,11 @@
 
 #include <ContactSensor.h>
 #include <TempSensor.h>
+
+enum SensorId : int {
+	WINDOW1 = 1,
+	WINDOW2 = 2,
+	WATER_SENSOR = 3,
+	TEMP_SENSOR = 4,
+	LIGHT_SENSOR = 5
+};
diff --git a/light_sensor/light_sensor.ino b/light_sensor/light_sensor.ino
new file mode 100644
index 0000000..b5b9050
--- /dev/null
+++ b/light_sensor/light_sensor.ino
@@ -0,0 +1,32 @@
+#include "Arduino.h"
+#include <TinyPower.h>
+#include <Tiny.h>
+
+// Pins
+#define SWITCH 0
+#define SENDER 2
+
+ContactSensor sensor = ContactSensor(LIGHT_SENSOR, SENDER);
+
+void setup() {
+
+  pinMode(SWITCH, INPUT_PULLUP);
+
+  sensor.setup();
+
+  sensor.sendStateAndVoltage(readState());
+
+  TinyPower::setup();
+}
+
+void loop() {
+  TinyPower::sleep();
+}
+
+boolean readState() {
+  return digitalRead(SWITCH);
+}
+
+ISR(PCINT0_vect) {
+  sensor.sendStateAndVoltage(!readState());
+}
diff --git a/temp_sensor/temp_sensor.ino b/temp_sensor/temp_sensor.ino
index 86d7eb6..a9178c0 100644
--- a/temp_sensor/temp_sensor.ino
+++ b/temp_sensor/temp_sensor.ino
@@ -8,15 +8,13 @@
 #define SENDER 1
 #define TEMP_PIN A1
 
-#define SENSOR_ID 4
-
 #if DEBUG
 #define RxD 3
 #define TxD 4
 SoftwareSerial AttinySerial(RxD, TxD);
 #endif
 
-TempSensor sensor = TempSensor(SENSOR_ID, SENDER);
+TempSensor sensor = TempSensor(TEMP_SENSOR, SENDER);
 
 int counter = 0;
 
diff --git a/water_sensor/water_sensor.ino b/water_sensor/water_sensor.ino
index 1c82c94..688c6d7 100644
--- a/water_sensor/water_sensor.ino
+++ b/water_sensor/water_sensor.ino
@@ -6,9 +6,7 @@
 #define SENDER 2
 #define CONTROLLER 4
 
-#define SENSOR_ID 3
-
-ContactSensor sensor = ContactSensor(SENSOR_ID, SENDER);
+ContactSensor sensor = ContactSensor(WATER_SENSOR, SENDER);
 
 int counter = 0;
 
diff --git a/window1/window1.ino b/window1/window1.ino
index 5f26177..d3baed2 100644
--- a/window1/window1.ino
+++ b/window1/window1.ino
@@ -5,9 +5,8 @@
 #define SWITCH 0
 #define SENDER 2
 #define CONTROLLER 4
-#define SENSOR_ID 1
 
-ContactSensor sensor = ContactSensor(SENSOR_ID, SENDER);
+ContactSensor sensor = ContactSensor(WINDOW1, SENDER);
 
 int counter = 0;
 bool currentState;
diff --git a/window2/window2.ino b/window2/window2.ino
index 56df2a5..5b7900c 100644
--- a/window2/window2.ino
+++ b/window2/window2.ino
@@ -4,9 +4,8 @@
 // Pins
 #define SWITCH 0
 #define SENDER 2
-#define SENSOR_ID 2
 
-ContactSensor sensor = ContactSensor(SENSOR_ID, SENDER);
+ContactSensor sensor = ContactSensor(WINDOW2, SENDER);
 
 int counter = 0;
 bool currentState;