Fixed debounce code to handle noisy switch transitions #989 (#1030)

* Fix debounce to handle noisy switch transitions

* Fix debounce to handle noisy switch transitions

* Fix debounce to handle noisy switch transitions

* Removed inline comment to see if Clang checker will be happy

* Test fix for supposed Clang formatting issue

firmware/application/hw/debounce.cpp

@@ -23,17 +23,24 @@
 
 #include "utility.hpp"
 
+// Returns TRUE if button state changed (after debouncing)
 bool Debounce::feed(const uint8_t bit) {
     history_ = (history_ << 1) | (bit & 1);
 
-    if (history_ == 0b00001111) {
-        state_ = 1;
-        return true;
+    if (state_ == 0) {
+        // Previous button state was 0 (released);
+        // Has button been held for DEBOUNCE_COUNT ticks?
+        if ((history_ & DEBOUNCE_MASK) == DEBOUNCE_MASK) {
+            state_ = 1;
+            return true;
+        }
+    } else {
+        // Previous button state was 1 (pressed);
+        // Has button been released for DEBOUNCE_COUNT ticks?
+        if ((history_ & DEBOUNCE_MASK) == 0) {
+            state_ = 0;
+            return true;
+        }
     }
-    if (history_ == 0b11110000) {
-        state_ = 0;
-        return true;
-    }
-
     return false;
 }

firmware/application/hw/debounce.hpp

@@ -24,6 +24,10 @@
 
 #include <cstdint>
 
+// consecutive # of times button input must be same (<=8)
+#define DEBOUNCE_COUNT 4
+#define DEBOUNCE_MASK ((1 << DEBOUNCE_COUNT) - 1)
+
 class Debounce {
    public:
     bool feed(const uint8_t bit);