diff --git a/src/main.rs b/src/main.rs
index e070df4..4ddd746 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -205,96 +205,134 @@ impl Show for NumberInput {
 
 #[derive(uDebug)]
 enum State {
-    EnterSignificant,
-    EnterExponent,
-    EnterOperation,
+    Trans(TransState),
+    Calc(CalcState),
+}
+
+#[derive(uDebug)]
+enum TransState {
     Err { timeout: usize },
 }
 
-impl State {
+impl TransState {
+    fn on_frame(
+        &mut self,
+        key: Option<KeyPress>,
+        number_input: &mut NumberInput,
+        calc: &mut Calc,
+    ) -> Option<CalcState> {
+        match self {
+            TransState::Err { timeout: 0 } => {
+                number_input.reset();
+                calc.reset();
+                Some(CalcState::EnterSignificant)
+            }
+            TransState::Err { timeout } => {
+                *timeout -= 1;
+                match key {
+                    Some(KeyPress::C) => {
+                        number_input.reset();
+                        calc.reset();
+                        Some(CalcState::EnterSignificant)
+                    }
+                    _ => None,
+                }
+            }
+        }
+    }
+}
+
+#[derive(uDebug)]
+enum CalcState {
+    EnterSignificant,
+    EnterExponent,
+    EnterOperation,
+}
+
+impl CalcState {
     fn on_key(
         &self,
         key: KeyPress,
         number_input: &mut NumberInput,
         calc: &mut Calc,
-    ) -> Result<State, ()> {
+    ) -> Result<CalcState, ()> {
         match self {
-            State::EnterSignificant => match key {
+            CalcState::EnterSignificant => match key {
                 KeyPress::C => {
                     number_input.reset();
                     calc.reset();
-                    Ok(State::EnterSignificant)
+                    Ok(CalcState::EnterSignificant)
                 }
                 KeyPress::Num(val) => {
                     number_input.input(val)?;
-                    Ok(State::EnterSignificant)
+                    Ok(CalcState::EnterSignificant)
                 }
                 KeyPress::Minus => {
                     number_input.toggle_minus();
-                    Ok(State::EnterSignificant)
+                    Ok(CalcState::EnterSignificant)
                 }
                 KeyPress::E => {
                     number_input.enter_exponent();
-                    Ok(State::EnterExponent)
+                    Ok(CalcState::EnterExponent)
                 }
-                _ => Ok(State::EnterSignificant),
+                _ => Ok(CalcState::EnterSignificant),
             },
-            State::EnterExponent => match key {
+            CalcState::EnterExponent => match key {
                 KeyPress::C => {
                     number_input.reset();
                     calc.reset();
-                    Ok(State::EnterSignificant)
+                    Ok(CalcState::EnterSignificant)
                 }
                 KeyPress::Num(val) => {
                     number_input.input(val)?;
-                    Ok(State::EnterExponent)
+                    Ok(CalcState::EnterExponent)
                 }
                 KeyPress::Minus => {
                     number_input.toggle_minus();
-                    Ok(State::EnterExponent)
+                    Ok(CalcState::EnterExponent)
                 }
                 KeyPress::E => {
                     number_input.done();
                     match calc.push(number_input.to_decimal()) {
-                        Ok(()) => Ok(State::EnterOperation),
+                        Ok(()) => Ok(CalcState::EnterOperation),
                         Err(_) => Err(()),
                     }
                 }
-                _ => Ok(State::EnterExponent),
+                _ => Ok(CalcState::EnterExponent),
             },
-            State::EnterOperation => match key {
+            CalcState::EnterOperation => match key {
                 KeyPress::Up => todo!(),
                 KeyPress::C => {
                     number_input.reset();
                     calc.reset();
-                    Ok(State::EnterSignificant)
+                    Ok(CalcState::EnterSignificant)
                 }
                 KeyPress::Num(_) => todo!(),
                 KeyPress::Mul => match calc.mul() {
                     Ok(dec) => {
                         number_input.set_result(dec)?;
-                        Ok(State::EnterOperation)
+                        Ok(CalcState::EnterOperation)
                     }
                     Err(_) => Err(()),
                 },
                 KeyPress::Div => match calc.div() {
                     Ok(dec) => {
                         number_input.set_result(dec)?;
-                        Ok(State::EnterOperation)
+                        Ok(CalcState::EnterOperation)
                     }
                     Err(_) => Err(()),
                 },
                 KeyPress::Plus => match calc.add() {
                     Ok(dec) => {
                         number_input.set_result(dec)?;
-                        Ok(State::EnterOperation)
+                        Ok(CalcState::EnterOperation)
                     }
                     Err(_) => Err(()),
                 },
                 KeyPress::Minus => match calc.sub() {
                     Ok(dec) => {
                         number_input.set_result(dec)?;
-                        Ok(State::EnterOperation)
+                        Ok(CalcState::EnterOperation)
                     }
                     Err(_) => Err(()),
                 },
@@ -304,18 +342,10 @@ impl State {
                         Err(())
                     } else {
                         number_input.reset();
-                        Ok(State::EnterSignificant)
+                        Ok(CalcState::EnterSignificant)
                     }
                 }
             },
-            State::Err { timeout } => match key {
-                KeyPress::C => {
-                    number_input.reset();
-                    calc.reset();
-                    Ok(State::EnterSignificant)
-                }
-                _ => Ok(State::Err { timeout: *timeout }),
-            },
         }
     }
 }
@@ -361,7 +391,7 @@ fn main() -> ! {
     number_input.show(&mut display);
 
     let mut calc = Calc::default();
-    let mut state = State::EnterSignificant;
+    let mut state = State::Calc(CalcState::EnterSignificant);
 
     loop {
         let mut last_key_readout: Option<KeyReadout> = None;
@@ -378,40 +408,37 @@ fn main() -> ! {
             io_select.set_off();
         }
 
-        match &mut state {
-            State::Err { timeout } if *timeout == 0 => {
-                number_input.reset();
-                calc.reset();
-                state = State::EnterSignificant;
-                number_input.show(&mut display);
-                ufmt::uwriteln!(&mut serial, "err timout state: {:?}", state).unwrap_infallible();
-            }
-            State::Err { timeout } => {
-                *timeout -= 1;
-            }
-            _ => (),
+        let key = debounce.input(last_key_readout);
+
+        if let Some(key) = &key {
+            ufmt::uwriteln!(&mut serial, "key: {:?} state: {:?}", key, state).unwrap_infallible();
         }
 
-        if let Some(key) = debounce.input(last_key_readout) {
-            ufmt::uwriteln!(&mut serial, "key: {:?} state: {:?}", key, state).unwrap_infallible();
-            match state.on_key(key, &mut number_input, &mut calc) {
-                Ok(new_state) => state = new_state,
-                Err(()) => {
-                    state = State::Err {
-                        timeout: ERROR_TIMEOUT,
+        match &mut state {
+            State::Trans(trans_state) => {
+                if let Some(calc_state) = trans_state.on_frame(key, &mut number_input, &mut calc) {
+                    state = State::Calc(calc_state);
+                }
+            }
+            State::Calc(calc_state) => {
+                if let Some(key) = key {
+                    match calc_state.on_key(key, &mut number_input, &mut calc) {
+                        Ok(new_state) => *calc_state = new_state,
+                        Err(()) => {
+                            state = State::Trans(TransState::Err {
+                                timeout: ERROR_TIMEOUT,
+                            });
+                        }
                     }
+                    ufmt::uwriteln!(&mut serial, "state: {:?} stack: {}", state, calc.len())
+                        .unwrap_infallible();
                 }
             }
-            ufmt::uwriteln!(&mut serial, "state: {:?} stack: {}", state, calc.len())
-                .unwrap_infallible();
-            match &state {
-                State::EnterSignificant | State::EnterExponent | State::EnterOperation => {
-                    number_input.show(&mut display)
-                }
-                State::Err { .. } => {
-                    display.error();
-                }
-            }
+        }
+
+        match &state {
+            State::Trans(_) => display.error(),
+            State::Calc(_) => number_input.show(&mut display),
         }
 
         arduino_hal::delay_ms(1);