diff --git a/src/main.cpp b/src/main.cpp
index b6220af..8d30c5b 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -7,8 +7,74 @@
 const char* ssid = "REPLACE_WITH_YOUR_SSID";
 const char* password = "REPLACE_WITH_YOUR_PASSWORD";
 
+class App {
+public:
+    virtual void loop() = 0;
+};
+
+class OTA: public App {
+public:
+    OTA() {
+        M5.Display.startWrite();
+        M5.Display.clearDisplay(TFT_WHITE);
+        M5.Display.setCursor(0, 10);
+        M5.Display.printf("SSID: %s\n", ssid);
+        M5.Display.printf("IP Address: %s\n", WiFi.localIP().toString());
+        M5.Display.printf("\n\n");
+        M5.Display.printf("Web server running on port 80\n");
+        M5.Display.printf("ElegantOTA available at\n"
+                          "http://%s/update\n",
+                          WiFi.localIP().toString());
+
+        button_power.initButton(&M5.Display, M5.Display.width() / 2, M5.Display.height() / 2, 200, 100, TFT_BLACK, TFT_LIGHTGRAY, TFT_BLACK, "Power", 3, 3);
+        button_power.drawButton();
+        M5.Display.endWrite();
+    }
+    void loop() {
+        auto t = M5.Touch.getDetail();
+        if (t.wasPressed()) {
+            if (button_power.contains(t.x, t.y)) {
+                button_power.press(true);
+            } else {
+                button_power.press(false);
+            }
+        } else {
+            button_power.press(false);
+        }
+        if (button_power.justReleased()) {
+            M5.Display.clearDisplay(TFT_WHITE);
+            M5.Power.powerOff();
+        }
+        yield();
+    }
+protected:
+    LGFX_Button button_power;
+};
+
+class Clock: public App {
+public:
+    Clock() {
+        M5.Display.clearDisplay(TFT_WHITE);
+    }
+    void loop() {
+        static constexpr const char* const wd[7] = {"Sun","Mon","Tue","Wed","Thr","Fri","Sat"};
+        auto dt = M5.Rtc.getDateTime();
+        M5.Display.setCursor(0, 15);
+        M5.Display.printf("RTC : %04d/%02d/%02d (%s)  %02d:%02d:%02d"
+               , dt.date.year
+               , dt.date.month
+               , dt.date.date
+               , wd[dt.date.weekDay]
+               , dt.time.hours
+               , dt.time.minutes
+               , dt.time.seconds
+               );
+        delay(500);
+    }
+};
+
 AsyncWebServer server(80);
-LGFX_Button button_power;
+App* app;
 
 void setup(void) {
     auto cfg = M5.config();
@@ -43,38 +109,19 @@ void setup(void) {
     server.begin();
     Serial.println("HTTP server started");
 
-    M5.Display.startWrite();
-    M5.Display.clearDisplay(TFT_WHITE);
-    M5.Display.setCursor(0, 10);
-    M5.Display.printf("SSID: %s\n", ssid);
-    M5.Display.printf("IP Address: %s\n", WiFi.localIP().toString());
-    M5.Display.printf("\n\n");
-    M5.Display.printf("Web server running on port 80\n");
-    M5.Display.printf("ElegantOTA available at\n"
-                      "http://%s/update\n",
-                      WiFi.localIP().toString());
-
-    button_power.initButton(&M5.Display, M5.Display.width() / 2, M5.Display.height() / 2, 200, 100, TFT_BLACK, TFT_LIGHTGRAY, TFT_BLACK, "Power", 3, 3);
-    button_power.drawButton();
-    M5.Display.endWrite();
+    app = new OTA;
 }
 
 void loop()
 {
     M5.update();
-    auto t = M5.Touch.getDetail();
-    if (t.wasPressed()) {
-        if (button_power.contains(t.x, t.y)) {
-            button_power.press(true);
-        } else {
-            button_power.press(false);
-        }
-    } else {
-        button_power.press(false);
-    }
-    if (button_power.justReleased()) {
-        M5.Display.clearDisplay(TFT_WHITE);
-        M5.Power.powerOff();
+    if (M5.BtnA.wasClicked()) {
+        delete app;
+        app = new Clock;
+    } else if (M5.BtnC.wasClicked()) {
+        delete app;
+        app = new OTA;
     }
+    app->loop();
     yield();
 }