diff --git a/boot.py b/boot.py
index 53ecedd..88943c0 100644
--- a/boot.py
+++ b/boot.py
@@ -1,79 +1,4 @@
-import time
+from sign import App
 
-from machine import Pin
-
-D1 = 5
-D2 = 4
-D3 = 0
-D4 = 2
-D5 = 14
-
-
-class Girl:
-    def __init__(
-        self, p_g: int = D1, p_i: int = D2, p_r: int = D3, p_l: int = D5
-    ) -> None:
-        self.pins = [
-            Pin(p_g, Pin.OUT),
-            Pin(p_i, Pin.OUT),
-            Pin(p_r, Pin.OUT),
-            Pin(p_l, Pin.OUT),
-        ]
-        for pin in self.pins:
-            pin.off()
-
-    def show(self, text: str) -> None:
-        for pin, value in zip(
-            self.pins,
-            [
-                int("g" in text),
-                int("i" in text),
-                int("r" in text),
-                int("l" in text),
-            ],
-        ):
-            pin.value(value)
-
-    def on(self) -> None:
-        for pin in self.pins:
-            pin.on()
-
-    def off(self) -> None:
-        for pin in self.pins:
-            pin.off()
-
-
-separate = [
-    "g",
-    "",
-    "i",
-    "",
-    "r",
-    "",
-    "l",
-    "",
-]
-
-flash = [
-    "girl",
-    "",
-    "girl",
-    "",
-    "girl",
-    "",
-]
-gradual = [
-    "g",
-    "gi",
-    "gir",
-    "girl",
-    "",
-]
-
-sign = Girl(D1, D2, D3, D5)
-
-while True:
-    for pattern in [separate, flash, gradual, gradual, flash]:
-        for state in pattern:
-            sign.show(state)
-            time.sleep(0.5)
+app = App()
+app.run()
diff --git a/sign.py b/sign.py
new file mode 100644
index 0000000..4c7b9c3
--- /dev/null
+++ b/sign.py
@@ -0,0 +1,170 @@
+import time
+
+from machine import Pin
+
+D1 = 5
+D2 = 4
+D3 = 0
+D4 = 2
+D5 = 14
+D6 = 12
+DEBOUNCE_DELAY = 50
+
+
+class Girl:
+    letters = list("GIRL")
+
+    def __init__(
+        self, p_g: int = D1, p_i: int = D2, p_r: int = D3, p_l: int = D5
+    ) -> None:
+        self.pins = [
+            Pin(p_g, Pin.OUT),
+            Pin(p_i, Pin.OUT),
+            Pin(p_r, Pin.OUT),
+            Pin(p_l, Pin.OUT),
+        ]
+        for pin in self.pins:
+            pin.off()
+
+    def show(self, text: str) -> None:
+        for pin, value in zip(
+            self.pins,
+            [
+                int("G" in text),
+                int("I" in text),
+                int("R" in text),
+                int("L" in text),
+            ],
+        ):
+            pin.value(value)
+
+    def on(self) -> None:
+        for pin in self.pins:
+            pin.on()
+
+    def off(self) -> None:
+        for pin in self.pins:
+            pin.off()
+
+
+def chain(iterators):
+    for iterator in iterators:
+        yield from iterator
+
+
+def cycle(iterator):
+    while True:
+        yield from iterator
+
+
+def repeat(value):
+    while True:
+        yield value
+
+
+class App:
+    MODE_STATIC = "static"
+    MODE_FLASH = "flash"
+    MODE_SEPARATE = "separate"
+    MODE_GRADUAL = "gradual"
+    MODE_COMBINED = "combined"
+
+    def __init__(self):
+        self.sign = Girl(D1, D2, D3, D5)
+        self.mode_switch_pressed = False
+        self.mode_switch_last = None
+        self.mode_switch_pin = Pin(D6, Pin.IN, Pin.PULL_UP)
+        self.modes = cycle(
+            [
+                self.MODE_STATIC,
+                self.MODE_FLASH,
+                self.MODE_SEPARATE,
+                self.MODE_GRADUAL,
+                self.MODE_COMBINED,
+            ]
+        )
+
+    @property
+    def pattern_static(self):
+        return [self.sign.letters]
+
+    @property
+    def pattern_flash(self):
+        return list(chain(zip(self.pattern_static, repeat(""))))
+
+    @property
+    def pattern_separate(self):
+        return self.sign.letters + [""]
+
+    @property
+    def pattern_gradual(self):
+        seq = [self.sign.letters[: i + 1] for i in range(len(self.sign.letters))]
+        return seq + [""]
+
+    @property
+    def pattern_combined(self):
+        return list(
+            chain(
+                [
+                    self.pattern_separate * 2,
+                    self.pattern_flash * 3,
+                    self.pattern_gradual * 2,
+                    self.pattern_flash * 3,
+                ]
+            )
+        )
+
+    def set_mode(self, mode):
+        self.mode = mode
+        if mode == self.MODE_STATIC:
+            self.states = cycle(self.pattern_static)
+        elif mode == self.MODE_FLASH:
+            self.states = cycle(self.pattern_flash)
+        elif mode == self.MODE_SEPARATE:
+            self.states = cycle(self.pattern_separate)
+        elif mode == self.MODE_GRADUAL:
+            self.states = cycle(self.pattern_gradual)
+        elif mode == self.MODE_COMBINED:
+            self.states = cycle(self.pattern_combined)
+        else:
+            return
+        self.mode = mode
+        print(f"[mode] mode='{mode}'")
+        self.update()
+
+    def update(self, delay=500):
+        self.state = next(self.states)
+        self.delay = delay
+        print(f"[update] state='{self.state}', delay={self.delay}")
+        self.sign.show(self.state)
+        self.last_update = time.ticks_ms()
+
+    def tick(self):
+        if (not self.mode_switch_pin.value()) != self.mode_switch_pressed:
+            if self.mode_switch_last is None:
+                self.mode_switch_last = time.ticks_ms()
+            elif (
+                time.ticks_diff(time.ticks_ms(), self.mode_switch_last) > DEBOUNCE_DELAY
+            ):
+                self.mode_switch_pressed = not self.mode_switch_pressed
+                self.mode_switch_last = None
+                print("BUTTON CHANGE", self.mode_switch_pressed)
+                if not self.mode_switch_pressed:
+                    # Was just released
+                    self.set_mode(next(self.modes))
+        elif time.ticks_diff(time.ticks_ms(), self.mode_switch_last) > DEBOUNCE_DELAY:
+            self.mode_switch_last = None
+        if time.ticks_diff(time.ticks_ms(), self.last_update) > self.delay:
+            self.update()
+
+    def run(self):
+        print("Starting application loop")
+        self.set_mode(next(self.modes))
+        while True:
+            self.tick()
+            time.sleep_ms(0)
+
+
+if __name__ == "__main__":
+    app = App()
+    app.run()