From 4d1269051b9fc9e2b0fdbd7bdd6ba8a631fd7b80 Mon Sep 17 00:00:00 2001
From: Mark Thompson <129641948+NotherNgineer@users.noreply.github.com>
Date: Sun, 21 May 2023 19:06:37 -0500
Subject: [PATCH] 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 +++++++++++++++--------
 firmware/application/hw/debounce.hpp |  4 ++++
 2 files changed, 19 insertions(+), 8 deletions(-)

diff --git a/firmware/application/hw/debounce.cpp b/firmware/application/hw/debounce.cpp
index 2e338a102..7caf4ed22 100644
--- a/firmware/application/hw/debounce.cpp
+++ b/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;
 }
diff --git a/firmware/application/hw/debounce.hpp b/firmware/application/hw/debounce.hpp
index 0d2ba1cd7..52dfe1061 100644
--- a/firmware/application/hw/debounce.hpp
+++ b/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);