diff --git a/src/src/main.cpp b/src/src/main.cpp
index 0835fe4..212a766 100644
--- a/src/src/main.cpp
+++ b/src/src/main.cpp
@@ -27,6 +27,9 @@ int password = 0; // 0-9999
 int passwordValue = 0;
 String savedPassword = "";
 
+// stav zámku
+bool isOpen = false;
+
 // enkodér
 int lastCLK = HIGH;
 
@@ -36,8 +39,8 @@ unsigned long lastEncoderMove = 0;
 bool masked = false;
 
 // přeformátování kódu na 4 cifry
-String formatCode(int value) {
-    String s = String(value);
+String formatCode(const int value) {
+    auto s = String(value);
     while (s.length() < 4) s = "0" + s;
     return s;
 }
@@ -48,8 +51,8 @@ void CloseLock() { servo.write(CLOSED_POS); }
 
 // chování bzučáku
 void OpenSound() {
-    int melody[] = { 262, 330, 392, 523 }; // C4, E4, G4, C5
-    int durations[] = { 150, 150, 150, 300 };
+    const int melody[] = { 262, 330, 392, 523 }; // C4, E4, G4, C5
+    const int durations[] = { 150, 150, 150, 300 };
 
     for (int i = 0; i < 4; i++) {
         tone(BUZZER_PIN, melody[i], durations[i]);
@@ -59,8 +62,8 @@ void OpenSound() {
 }
 
 void CloseSound() {
-    tone(BUZZER_PIN, 262, 150);
-    delay(500);
+    tone(BUZZER_PIN, 200, 200); delay(230);
+    tone(BUZZER_PIN, 150, 400); delay(430);
     noTone(BUZZER_PIN);
 }
 
@@ -110,15 +113,28 @@ void ButtonPressed() {
     }
 }
 
-// setup hesla
-void showSetupScreen(bool showValue) {
+// zobrazení zadávací obrazovky
+void showEntryScreen(const bool showValue) {
+    lcd.setCursor(0, 0);
+    lcd.printstr("Zadejte heslo:  ");
+    lcd.setCursor(0, 1);
+    if (showValue) {
+        String code = formatCode(password);
+        const String display = code[0] + String(" ") + code[1] + String(" ") + code[2] + String(" ") + code[3] + String("        ");
+        lcd.printstr(display.c_str());
+    } else {
+        lcd.printstr("*  *  *  *      ");
+    }
+}
+
+// zobrazení setup obrazovky
+void showSetupScreen(const bool showValue) {
     lcd.setCursor(0, 0);
     lcd.printstr("Nastavte heslo: ");
     lcd.setCursor(0, 1);
     if (showValue) {
         String code = formatCode(passwordValue);
-        // mezery okolo pro vizuální oddělení číslic
-        String display = code[0] + String(" ") + code[1] + String(" ") + code[2] + String(" ") + code[3] + String("        ");
+        const String display = code[0] + String(" ") + code[1] + String(" ") + code[2] + String(" ") + code[3] + String("        ");
         lcd.printstr(display.c_str());
     } else {
         lcd.printstr("*  *  *  *      ");
@@ -137,10 +153,9 @@ void runPasswordSetup() {
 
     while (savedPassword == "") {
         // čtení enkodéru
-        int currentCLK = digitalRead(ENCODER_CLK_PIN);
+        const int currentCLK = digitalRead(ENCODER_CLK_PIN);
         if (currentCLK != lastCLK && currentCLK == LOW) {
-            int dt = digitalRead(ENCODER_DT_PIN);
-            if (dt != currentCLK) {
+            if (const int dt = digitalRead(ENCODER_DT_PIN); dt != currentCLK) {
                 passwordValue = (passwordValue + 1) % 10000;
             } else {
                 passwordValue = (passwordValue - 1 + 10000) % 10000;
@@ -227,5 +242,72 @@ void setup() {
 }
 
 void loop() {
+    // čtení enkodéru – jen pokud je zamčeno
+    // (při odemčeném stavu enkodér nemá smysl)
+    if (!isOpen) {
+        const int currentCLK = digitalRead(ENCODER_CLK_PIN);
+        if (currentCLK != lastCLK && currentCLK == LOW) {
+            if (const int dt = digitalRead(ENCODER_DT_PIN); dt != currentCLK) {
+                password = (password + 1) % 10000;
+            } else {
+                password = (password - 1 + 10000) % 10000;
+            }
+            masked = false;
+            lastEncoderMove = millis();
+            showEntryScreen(true);
+        }
+        lastCLK = currentCLK;
 
-}
\ No newline at end of file
+        // maskování po nečinnosti
+        if (!masked && millis() - lastEncoderMove >= MASK_DELAY_MS) {
+            masked = true;
+            showEntryScreen(false);
+        }
+    }
+
+    // tlačítko
+    if (digitalRead(BUTTON_PIN) == HIGH) {
+        // debounce
+        while (digitalRead(BUTTON_PIN) == HIGH) {}
+        delay(50);
+
+        if (!isOpen) {
+            // pokus o odemčení
+            if (formatCode(password) == savedPassword) {
+                isOpen = true;
+                OpenLock();
+                OpenLED();
+                OpenSound();
+
+                lcd.setCursor(0, 0);
+                lcd.printstr("Odemceno!       ");
+                lcd.setCursor(0, 1);
+                lcd.printstr("Stiskni pro zamk");
+            } else {
+                CloseSound();
+
+                lcd.setCursor(0, 0);
+                lcd.printstr("Spatne heslo!   ");
+                lcd.setCursor(0, 1);
+                lcd.printstr("                ");
+                delay(1500);
+
+                // návrat na zadávací obrazovku, hodnota zachována
+                masked = false;
+                lastEncoderMove = millis();
+                showEntryScreen(true);
+            }
+        } else {
+            // zamčení
+            isOpen = false;
+            CloseLock();
+            CloseLED();
+            CloseSound();
+
+            password = 0;
+            masked = false;
+            lastEncoderMove = millis();
+            showEntryScreen(true);
+        }
+    }
+}