diff --git a/ch32v-insert-coin/src/app.rs b/ch32v-insert-coin/src/app.rs
new file mode 100644
index 0000000..81caeee
--- /dev/null
+++ b/ch32v-insert-coin/src/app.rs
@@ -0,0 +1,66 @@
+#[derive(Default)]
+pub enum State {
+    // system is asleep, waiting for wake from coin insertion
+    DeepSleep,
+    // system is in low-power mode, dimmed lights, waiting for interaction
+    Idle,
+    // system is active. on entry: play coin sound. on button press: play different sound
+    #[default]
+    Active,
+}
+
+mod settings {
+    pub enum Level {
+        Off,
+        Low,
+        Medium,
+        High,
+        Maximum,
+    }
+
+    impl Level {
+        pub fn next(&mut self) {
+            *self = match self {
+                Self::Off => Self::Low,
+                Self::Low => Self::Medium,
+                Self::Medium => Self::High,
+                Self::High => Self::Maximum,
+                Self::Maximum => Self::Off,
+            };
+        }
+    }
+
+    pub struct Settings {
+        pub brightness: Level,
+        pub volume: Level,
+        pub button_sound_index: usize,
+    }
+
+    impl Default for Settings {
+        fn default() -> Self {
+            Self {
+                brightness: Level::Medium,
+                volume: Level::Medium,
+                button_sound_index: 0,
+            }
+        }
+    }
+}
+
+pub use settings::Settings;
+
+pub struct App {
+    state: State,
+    pub settings: Settings,
+    // TODO: make this the "sound module" or whatever.
+    // synthesizers: AppSynthesizers,
+}
+
+impl Default for App {
+    fn default() -> Self {
+        Self {
+            state: State::default(),
+            settings: Settings::default(),
+        }
+    }
+}
diff --git a/ch32v-insert-coin/src/main.rs b/ch32v-insert-coin/src/main.rs
index ed5e986..f044b57 100644
--- a/ch32v-insert-coin/src/main.rs
+++ b/ch32v-insert-coin/src/main.rs
@@ -13,6 +13,9 @@ mod system;
 mod synthesizer;
 use synthesizer::AppSynthesizers;
 
+mod app;
+use app::App;
+
 use ch32_hal::{adc::AdcChannel, interrupt::typelevel::Handler, timer::low_level::OutputPolarity};
 use insert_coin::{CoreConfig, InsertCoin, SimplePwmCore};
 
@@ -28,42 +31,6 @@ use hal::println;
 
 use qingke::riscv;
 
-enum Level {
-    Off,
-    Low,
-    Medium,
-    High,
-    Maximum,
-}
-
-impl Level {
-    pub fn next(&mut self) {
-        *self = match self {
-            Self::Off => Self::Low,
-            Self::Low => Self::Medium,
-            Self::Medium => Self::High,
-            Self::High => Self::Maximum,
-            Self::Maximum => Self::Off,
-        };
-    }
-}
-
-struct Settings {
-    brightness: Level,
-    volume: Level,
-    button_sound_index: usize,
-}
-
-impl Default for Settings {
-    fn default() -> Self {
-        Self {
-            brightness: Level::Medium,
-            volume: Level::Medium,
-            button_sound_index: 0,
-        }
-    }
-}
-
 struct DebouncedGPIO<'a> {
     input: Input<'a>,
     // value of the GPIO
@@ -508,7 +475,8 @@ fn app_main(mut p: hal::Peripherals, mut delay: Delay) -> ! {
     interfaces.set_active(true);
     // insert_coin.init();
 
-    let mut settings = Settings::default();
+    // let mut settings = Se::default();
+    let mut app = App::default();
 
     let mut led0_index = 0;
     let led0_dcs = [0u8, 25u8, 50u8, 75u8, 100u8, 75u8, 50u8, 25u8];
@@ -672,10 +640,10 @@ fn app_main(mut p: hal::Peripherals, mut delay: Delay) -> ! {
                     //     .dac
                     //     .load_data(button_sounds[settings.button_sound_index]);
 
-                    settings.button_sound_index += 1;
-                    if settings.button_sound_index > 2 {
+                    app.settings.button_sound_index += 1;
+                    if app.settings.button_sound_index > 2 {
                         // if settings.button_sound_index > button_sounds.len() - 1 {
-                        settings.button_sound_index = 0;
+                        app.settings.button_sound_index = 0;
                     }
                     #[cfg(feature = "enable_print")]
                     println!("reset hold timers + enable");
@@ -691,13 +659,13 @@ fn app_main(mut p: hal::Peripherals, mut delay: Delay) -> ! {
             if volume_btn_input.ready() {
                 #[cfg(feature = "enable_print")]
                 println!("volume btn value: {}", volume_btn_input.value());
-                settings.volume.next();
+                app.settings.volume.next();
                 volume_btn_input.reset();
             }
             if light_ctrl_btn_input.ready() {
                 #[cfg(feature = "enable_print")]
                 println!("light_ctrl_btn value: {}", light_ctrl_btn_input.value());
-                settings.brightness.next();
+                app.settings.brightness.next();
                 light_ctrl_btn_input.reset();
             }