From 6a8f4f364b05ed714943820a06c6e3109190ef5f Mon Sep 17 00:00:00 2001
From: Russell Gilbert <russell@sandyatom.org>
Date: Sat, 7 Feb 2026 06:44:18 +0000
Subject: [PATCH] Refactors heart beat mechanism with gpiod

Updates the heart beat mechanism to use a prepared request to control the GPIO line, improving efficiency and code clarity.
Removes the direct line request in the beat function.
Switches to using pkg-config to manage dependencies and linker flags.
---
 src/RobotNode/CMakeLists.txt         | 19 ++++++++----
 src/RobotNode/CardioCenter/Heart.cpp | 45 ++++++++++++++++++----------
 src/RobotNode/CardioCenter/Heart.h   | 25 +++++++++-------
 3 files changed, 58 insertions(+), 31 deletions(-)

diff --git a/src/RobotNode/CMakeLists.txt b/src/RobotNode/CMakeLists.txt
index 65145f2..955da47 100644
--- a/src/RobotNode/CMakeLists.txt
+++ b/src/RobotNode/CMakeLists.txt
@@ -1,12 +1,18 @@
 # Sets the minimum CMake version required to handle modern C++ features
-cmake_minimum_required(VERSION 4.1)
+cmake_minimum_required(VERSION 3.10) # Version 4.1 doesn't exist yet (standard is 3.x)
 
-# Defines the project name (used for internal variable naming and IDE display
+# Defines the project name
 project(Dixon)
 
-# Forces the compiler to use C++20 features (required for modern libgpiod)
+# Forces the compiler to use C++20 features
 set(CMAKE_CXX_STANDARD 20)
 
+# Load the PkgConfig tool to find libraries automatically
+find_package(PkgConfig REQUIRED)
+
+# Search for libgpiod v2.x C++ bindings
+pkg_check_modules(GPIOD REQUIRED libgpiodcxx)
+
 # Define the executable and its source files
 add_executable(Dixon main.cpp
         DixonNodeState.cpp
@@ -16,5 +22,8 @@ add_executable(Dixon main.cpp
         CardioCenter/Heart.cpp
         CardioCenter/Heart.h)
 
-# 2. Tell the linker what libraries to "glue" to that executable
-target_link_libraries(Dixon PRIVATE gpiodcxx gpiod)
\ No newline at end of file
+# Add the Include directories found by PkgConfig (where the .hpp files live)
+target_include_directories(Dixon PRIVATE ${GPIOD_INCLUDE_DIRS})
+
+# Link the specific libraries found by PkgConfig
+target_link_libraries(Dixon PRIVATE ${GPIOD_LIBRARIES})
\ No newline at end of file
diff --git a/src/RobotNode/CardioCenter/Heart.cpp b/src/RobotNode/CardioCenter/Heart.cpp
index fb3e3a9..49dc742 100644
--- a/src/RobotNode/CardioCenter/Heart.cpp
+++ b/src/RobotNode/CardioCenter/Heart.cpp
@@ -1,22 +1,35 @@
 #include "Heart.h"
+#include <gpiod.hpp>
 
-Heart::Heart(const char* chipName, unsigned int lineOffset)
-    : _chip(chipName),
-      _line(_chip.get_line(lineOffset)),
-      _isOn(false)
+namespace cardio
 {
-    // Request the GPIO line as an output, initial value LOW
-    _line.request(
-        { "heart", gpiod::line_request::DIRECTION_OUTPUT, 0 },
-        0
-    );
-}
+     Heart::Heart(const char* chipName, unsigned int lineOffset)
+    : _isOn(false),
+      _request(setup_request(chipName, lineOffset))
+    {
+    }
 
-void Heart::beat()
-{
-    // Toggle the state
-    _isOn = !_isOn;
+    void Heart::beat()
+    {
+        _isOn = !_isOn;
+        auto val = _isOn ? gpiod::line::value::ACTIVE : gpiod::line::value::INACTIVE;
 
-    // Write the new value to the GPIO line
-    _line.set_value(_isOn ? 1 : 0);
+        _request.set_value(HEART_LINE_INDEX, val);
+    }
+
+    gpiod::line_request Heart::setup_request(const char* chipName, const unsigned int lineOffset)
+     {
+         std::string chipPath = std::string("/dev/") + chipName;
+         gpiod::chip chip(chipPath);
+
+         auto settings = gpiod::line_settings()
+             .set_direction(gpiod::line::direction::OUTPUT);
+
+         auto line_cfg = gpiod::line_config();
+         line_cfg.add_line_settings(lineOffset, settings);
+
+         return chip.prepare_request()
+                    .set_line_config(line_cfg)
+                    .do_request();
+     }
 }
\ No newline at end of file
diff --git a/src/RobotNode/CardioCenter/Heart.h b/src/RobotNode/CardioCenter/Heart.h
index a76a30e..fe355bc 100644
--- a/src/RobotNode/CardioCenter/Heart.h
+++ b/src/RobotNode/CardioCenter/Heart.h
@@ -1,16 +1,21 @@
 #pragma once
 #include <gpiod.hpp>
 
-class Heart
+namespace cardio
 {
-public:
-    Heart(const char* chipName = "gpiochip0", unsigned int lineOffset = 17);
+    class Heart
+    {
 
-    // DixonBrain calls this when a beat occurs
-    void beat();
+    public:
+        explicit Heart(const char* chipName = GPIO_CHIP_NAME, unsigned int lineOffset = DEFAULT_HEART_PIN);
+        void beat();
 
-private:
-    gpiod::chip _chip;
-    gpiod::line _line;
-    bool _isOn;
-};
\ No newline at end of file
+    private:
+        static constexpr auto GPIO_CHIP_NAME = "gpiochip0";
+        static constexpr unsigned int DEFAULT_HEART_PIN = 17;
+        static constexpr unsigned int HEART_LINE_INDEX = 0;
+        static gpiod::line_request setup_request(const char* chipName, unsigned int lineOffset);
+        bool _isOn;
+        gpiod::line_request _request;
+    };
+}