Add just pressed buttons

src/async_io.rs

@@ -85,6 +85,13 @@ impl Keypad {
         })
     }
 
+    pub fn just_pressed_buttons(&self) -> BTreeSet<KeypadButton> {
+        critical_section::with(|cs| {
+            let presses = self.presses.borrow_ref(cs);
+            presses.keys().copied().collect()
+        })
+    }
+
     pub fn clear(&self) {
         critical_section::with(|cs| {
             let mut presses = self.presses.borrow_ref_mut(cs);