key debounce

src/main.rs

@@ -290,7 +290,7 @@ impl Default for DispalyState {
     }
 }
 
-#[derive(uDebug, Clone, Copy)]
+#[derive(uDebug, Clone, Copy, PartialEq, Eq)]
 enum InputKey {
     Up,
     C,
@@ -350,6 +350,32 @@ impl<KN: AdcChannel<Atmega, ADC>, KO: AdcChannel<Atmega, ADC>> Input<KN, KO> {
     }
 }
 
+#[derive(Default)]
+struct Debounce {
+    history: [Option<InputKey>; 4],
+    pos: usize,
+    last: Option<InputKey>,
+}
+
+impl Debounce {
+    fn input(&mut self, key: Option<InputKey>) -> Option<InputKey> {
+        self.history[self.pos] = key;
+        self.pos += 1;
+        if self.pos >= self.history.len() {
+            self.pos = 0;
+        }
+        if self.history.iter().all(|hist| hist == &key) && self.last != key {
+            self.last = key;
+            key
+        } else if self.history.iter().all(|hist| hist == &None) {
+            self.last = None;
+            None
+        } else {
+            None
+        }
+    }
+}
+
 #[arduino_hal::entry]
 fn main() -> ! {
     let dp = arduino_hal::Peripherals::take().unwrap();
@@ -388,6 +414,7 @@ fn main() -> ! {
 
     let mut adc = Adc::new(dp.ADC, Default::default());
     let input = Input::new(ADC7, ADC6);
+    let mut debounce = Debounce::default();
 
     let mut display = DispalyState::default();
     display.0[0] = SegmentState::Num(0, true);
@@ -416,17 +443,10 @@ fn main() -> ! {
             io_select.set_off();
         }
 
-        if let Some((no, kn, ko)) = key {
-            let key = InputKey::map(no, kn, ko);
-            ufmt::uwriteln!(
-                &mut serial,
-                "no: {} kn: {} ko: {} key: {:?}",
-                no,
-                kn,
-                ko,
-                key
-            )
-            .unwrap_infallible();
+        let key = key.and_then(|(no, kn, ko)| InputKey::map(no, kn, ko));
+
+        if let Some(key) = debounce.input(key) {
+            ufmt::uwriteln!(&mut serial, "key: {:?}", key).unwrap_infallible();
         }
         arduino_hal::delay_ms(1);
     }