From 436c594cd81186324ec77eacd1e8284dcda76f81 Mon Sep 17 00:00:00 2001
From: Himsara Gallege <manurahimsara@gmail.com>
Date: Wed, 1 Sep 2021 07:36:36 +0000
Subject: [PATCH 1/3] Added Basic Functions

---
 heartbeat_listener.py | 63 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 63 insertions(+)
 create mode 100644 heartbeat_listener.py

diff --git a/heartbeat_listener.py b/heartbeat_listener.py
new file mode 100644
index 0000000..db604ad
--- /dev/null
+++ b/heartbeat_listener.py
@@ -0,0 +1,63 @@
+#!/usr/bin/env python3
+
+#--**--..--**--..--**--..--**--..--**--..--**--..--**--..--**--..--**--
+# 
+# Currently, it will flash the LED red if no heartbeat found 
+#
+# Author: Harrison
+# Last modified 22/03/21 by: Harrison
+# Translated to ROS2 by: Himsara
+#
+# Subscribed topics:
+#    - /base/heartbeat
+#--..--**--..--**--..--**--..--**--..--**--..--**--..--**--..--**--..--
+
+'''
+NOVA ROVER TEAM
+This node listens to heartbeat from base and performs actions if not received
+Currently, it will flash the LED red if no heartbeat found
+Author: Himsara Gallege
+'''
+
+import rclpy
+from rclpy.node import Node
+
+from std_msgs.msg import String
+
+class HeartbeatSub(Node):
+    # Store whether or not a beat has been found
+    beat = False
+    beat_count = 0
+
+    # The time out and loop counts
+    LOOP_HERTZ = 50
+    TIME_OUT = 25
+
+    # The initialisation function
+    def __init__ (self):
+        print("Initialising Heartbeat Subscriber class.")
+        super().__init__('HeartbeatSub')
+        self.subscription = self.create_subscription(String, 'topic', self.callback_func, 10)
+        self.subscription  # prevent unused variable warning
+
+        # Run the check node for seeing if heartbeat exists
+        self.check_heartbeat()
+
+    # Called when received heartbeat information
+    def received_cb (self, data):
+        self.heartbeat()
+        self.beat_count = 0
+
+
+    # When heartbeat times out
+    def no_heartbeat (self):
+	self.beat = False
+        print("\033[1;31;48mNo Heartbeart Detected\033[0;0m")
+
+
+    # When heartbeat returns
+    def heartbeat (self):
+	if not self.beat:
+	    print("\033[1;31;44mHeartbeat Returned\033[0;0m")
+	self.beat = True
+

From 50f807e15ee55379d0f31ea76e87ce1e0665f886 Mon Sep 17 00:00:00 2001
From: Himsara Gallege <manurahimsara@gmail.com>
Date: Wed, 1 Sep 2021 08:11:29 +0000
Subject: [PATCH 2/3] Added check heartbeat function

---
 heartbeat_listener.py | 17 ++++++++++++-----
 1 file changed, 12 insertions(+), 5 deletions(-)

diff --git a/heartbeat_listener.py b/heartbeat_listener.py
index db604ad..51f0432 100644
--- a/heartbeat_listener.py
+++ b/heartbeat_listener.py
@@ -36,18 +36,25 @@ class HeartbeatSub(Node):
     # The initialisation function
     def __init__ (self):
         print("Initialising Heartbeat Subscriber class.")
-        super().__init__('HeartbeatSub')
-        self.subscription = self.create_subscription(String, 'topic', self.callback_func, 10)
-        self.subscription  # prevent unused variable warning
 
-        # Run the check node for seeing if heartbeat exists
-        self.check_heartbeat()
+        # ROS initialisation
+        super().__init__('HeartbeatSub')
+        self.subscription = self.create_subscription(Empty, 'base/heartbeat', self.callback_func, 10)
+ 
+        # Create timer to run checkheartbeat frequently
+        self.timer = self.create_timer(0.1, self.check_heartbeat)
 
     # Called when received heartbeat information
     def received_cb (self, data):
         self.heartbeat()
         self.beat_count = 0
 
+    def check_heartbeat(self):
+        if self.beat_count <= TIME_OUT:
+            self.beat_count += 1
+        else:
+            self.no_heartbeat()
+
 
     # When heartbeat times out
     def no_heartbeat (self):

From 9033ddebdb76f920453ad4179fc242c3c9877cc7 Mon Sep 17 00:00:00 2001
From: Himsara Gallege <manurahimsara@gmail.com>
Date: Wed, 1 Sep 2021 21:56:58 +0000
Subject: [PATCH 3/3] Added paramter and description

---
 heartbeat_listener.py | 18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/heartbeat_listener.py b/heartbeat_listener.py
index 51f0432..6b91909 100644
--- a/heartbeat_listener.py
+++ b/heartbeat_listener.py
@@ -40,12 +40,17 @@ def __init__ (self):
         # ROS initialisation
         super().__init__('HeartbeatSub')
         self.subscription = self.create_subscription(Empty, 'base/heartbeat', self.callback_func, 10)
+
+        y_parameter_descriptor = ParameterDescriptor(description='Rover Heartbeat Parameter')
+
+        # Declare Parameter
+        self.declare_parameter('/rover/heartbeat')
  
         # Create timer to run checkheartbeat frequently
         self.timer = self.create_timer(0.1, self.check_heartbeat)
 
     # Called when received heartbeat information
-    def received_cb (self, data):
+    def callback_func (self, data):
         self.heartbeat()
         self.beat_count = 0
 
@@ -55,16 +60,19 @@ def check_heartbeat(self):
         else:
             self.no_heartbeat()
 
+        # Set parameter
+        self.set_parameters([Parameter('/rover/heartbeat', Parameter.Type.BOOL, self.beat_count <= TIME_OUT)])
+
 
     # When heartbeat times out
     def no_heartbeat (self):
-	self.beat = False
+        self.beat = False
         print("\033[1;31;48mNo Heartbeart Detected\033[0;0m")
 
 
     # When heartbeat returns
     def heartbeat (self):
-	if not self.beat:
-	    print("\033[1;31;44mHeartbeat Returned\033[0;0m")
-	self.beat = True
+        if not self.beat:
+            print("\033[1;31;44mHeartbeat Returned\033[0;0m")
+        self.beat = True