diff --git a/include/devices.h b/include/devices.h
index 1bd3fe5..9c1e90c 100644
--- a/include/devices.h
+++ b/include/devices.h
@@ -37,13 +37,13 @@ namespace Devices {
 
     auto brightnessMqtt = Builder<Number>::instance(new Number{ "Brightness", "brightness",
             [](const char* msg) {
-                Display::Brightness::set(String{ msg }.toInt());
+                Display::brightness = String{ msg }.toInt();
             }
-        }).withMin(BRIGHTNESS_MIN).withMax(BRIGHTNESS_MAX).withStep(BRIGHTNESS_STEP).restoreStateFromCommand().build();
+        }).withMin(Display::Brightness::MIN).withMax(Display::Brightness::MAX).withStep(1).restoreStateFromCommand().build();
 
     auto hourFormatMqtt = Builder<Switch>::instance(new Switch{ "Format 24h", "format_24h",
             [](const char* msg) {
-                strcmp("ON", msg) == 0 ? Display::changeHourFormat24(true) : Display::changeHourFormat24(false);
+                Display::hourFormat24 = (strcmp("ON", msg) == 0);
             }
         }).restoreStateFromCommand().build();
     Number* displayTimerMqtt = Builder<Number>::instance(new Number{ "Timer duration", "timer_duration",
@@ -131,14 +131,14 @@ namespace Devices {
     }
 
     void setup() {
-        Display::hourFormatChangedCallback = []{
+        Display::hourFormat24.registerCallback([]{
             hourFormatMqtt->updateState(Display::hourFormat24);
-        };
-        Display::Brightness::brightnessChangedCallback = []{
-            brightnessMqtt->updateState(Display::Brightness::current);
-        };
-        Display::Timer::remainingCallback = [](int8 current){
+        });
+        Display::brightness.registerCallback([]{
+            brightnessMqtt->updateState(Display::brightness);
+        });
+        Display::Timer::timer.registerCallback([](int8 current){
             timerRemainingMqtt->updateState(to_string(current).c_str());
-        };
+        });
     }
 }
\ No newline at end of file
diff --git a/include/display.h b/include/display.h
index dce6e48..6e798e4 100644
--- a/include/display.h
+++ b/include/display.h
@@ -8,17 +8,23 @@
 #include "bme.h"
 
 #define DISPLAY_ADDRESS 0x70
-#define BRIGHTNESS_MIN 0
-#define BRIGHTNESS_MAX 15
-#define BRIGHTNESS_STEP 1
-#define BRIGHTNESS_NIGHT BRIGHTNESS_MIN
-#define BRIGHTNESS_DAY 11
 #define MILLISECONDS(value) value*TASK_MILLISECOND
 #define SECONDS(value) value*TASK_SECOND
 #define MINUTES(value) value*TASK_MINUTE
 #define DISPLAY_SENSOR_ITERATIONS 2+1
 #define DISPLAY_DELAY (SECONDS(2))
 
+typedef void (*callback_t)();
+
+template <typename T>
+struct CallbackAware {
+    void registerCallback(T f) {
+        callback = f;
+    }
+protected:
+    T callback;
+};
+
 namespace Display {
 
     void displayTime();
@@ -56,35 +62,77 @@ namespace Display {
             tDisplayTime.enable();
         });
 
-    bool hourFormat24 = false;
-    void (*hourFormatChangedCallback)();
+    struct HourFormat : public CallbackAware<callback_t> {
+
+        operator bool() {
+            return format24;
+        }
+
+        void operator=(bool value) {
+            format24 = value;
+            tDisplayTime.restart();
+            if (callback) callback();
+        }
+    private:
+        bool format24 = false;
+    } hourFormat24;
 
     // Create display object
     Adafruit_7segment clockDisplay = Adafruit_7segment();
 
-    namespace Brightness {
-        uint8_t current = BRIGHTNESS_NIGHT;
-        void (*brightnessChangedCallback)();
+    struct Brightness : public CallbackAware<callback_t> {
+        static constexpr uint8 MIN = 0;
+        static constexpr uint8 MAX = 15;
+        static constexpr uint8 DAY = 11;
+        static constexpr uint8 NIGHT = MIN;
 
-        void set(uint8_t value) {
-            current = value % (BRIGHTNESS_MAX + 1);
+        void operator=(uint8 value) {
+            current = value % (MAX + 1);
             clockDisplay.setBrightness(current);
-            if (brightnessChangedCallback) brightnessChangedCallback();
+            if (callback) callback();
         }
 
-        void change(bool increase) {
-            increase ? set(current + BRIGHTNESS_STEP) : set(current - BRIGHTNESS_STEP);
+        operator uint8() {
+            return current;
         }
-    }
+
+    private:
+        uint8 current = NIGHT;
+    } brightness;
 
     namespace Timer {
-        int8 timer = 0, current = 0;
-        void (*remainingCallback)(int8);
+        typedef void (*remaining_callback_t)(int8);
+        struct : public CallbackAware<remaining_callback_t> {
+
+            void operator=(int8 value) {
+                initial = remaining = value;
+            }
+
+            operator int8() {
+                return remaining;
+            }
+
+            void start() {
+                remaining = initial + 1;
+            }
+
+            void decrease() {
+                remaining--;
+                if (callback) callback(remaining);
+            }
+
+            bool atBeginning() {
+                return initial == remaining;
+            }
+        
+        private:
+            int8 initial = 0, remaining = 0;
+        } timer;
 
         Task tDisplayTimer(SECONDS(10), TASK_ONCE + 1, 
             []{
-                if (current >= 0) {
-                    clockDisplay.print(current, DEC);
+                if (timer >= 0) {
+                    clockDisplay.print(timer, DEC);
                     clockDisplay.writeDisplay();
                 }
             }, &ts, false,
@@ -100,18 +148,17 @@ namespace Display {
         Task tTimer(MINUTES(1), TASK_FOREVER, 
             []{
                 static constexpr uint8 threshold = 16;
-                current--;
-                if (current == timer) {
+                timer.decrease();
+                if (timer.atBeginning()) {
                     if (timer <= threshold) tDisplayTimer.setIterations(TASK_FOREVER);
                     tDisplayTimer.restart();
-                } else if (current == threshold) {
+                } else if (timer == threshold) {
                     tDisplayTimer.setIterations(TASK_FOREVER);
                     tDisplayTimer.restart();
                 }
-                if (remainingCallback) remainingCallback(current);
             }, &ts, false, 
             []{
-                current = timer+1;
+                timer.start();
                 return true;
             },
             []{
@@ -155,11 +202,11 @@ namespace Display {
                     Ntp::tUpdateTime.restart();
                 }
                 if (currentHour == 8) {
-                    Brightness::set(BRIGHTNESS_DAY);
+                    brightness = Brightness::DAY;
                     Wifi::tConnect.enable();
                 }
                 if (currentHour == 17) {
-                    Brightness::set(BRIGHTNESS_NIGHT);
+                    brightness = Brightness::NIGHT;
                 }
             }
             static int currentMin = -1;
@@ -194,7 +241,7 @@ namespace Display {
         tDisplaySensor.setCallback(&displayTemp);
     }
 
-    void displayValue(uint8_t value) {
+    void displayValue(uint8 value) {
         tDisplayTime.disable();
         clockDisplay.print(value, HEX);
         clockDisplay.writeDisplay();
@@ -224,15 +271,9 @@ namespace Display {
         clockDisplay.writeDisplay();
     }
 
-    void changeHourFormat24(bool format24) {
-        hourFormat24 = format24;
-        tDisplayTime.restart();
-        if (hourFormatChangedCallback) hourFormatChangedCallback();
-    }
-
     void setup() {
         clockDisplay.begin(DISPLAY_ADDRESS);
-        clockDisplay.setBrightness(Brightness::current);
+        clockDisplay.setBrightness(brightness);
         tDisplayTime.enable();
     }
 }