Index: scripts/update_package_script/update_package.py
===================================================================
diff -u -r4958f2a616031e26b9d0f662b4faca8b28832a53 -r167604cac199c133488d55eb0163e88eadd0e123
--- scripts/update_package_script/update_package.py	(.../update_package.py)	(revision 4958f2a616031e26b9d0f662b4faca8b28832a53)
+++ scripts/update_package_script/update_package.py	(.../update_package.py)	(revision 167604cac199c133488d55eb0163e88eadd0e123)
@@ -61,6 +61,8 @@
         """
         status = False
         self._reset_variables()
+        # Create the CAN listener list from the Leahi messages
+        self._utilities.clear_can_listener()
         # TODO how to read from a manifest file. Right now it is passed directly
         # TODO if stack to update and stack target are not provided, then just read through the manifest files
         if stack_to_update is not None and destination is not None:
@@ -234,15 +236,12 @@
 
         @return none
         """
-
-        # Reset firmware
-        # Wait for the bootloader to come up
-        # Start updating
-
         list_of_binary_files = self._find_binary_files(packages_dir)
         if len(list_of_binary_files) == 0: exit(0)  # No binary files to process
 
-        #self._handle_broadcast_message_thread(start_thread=True)
+        self._utilities.send_update_available_to_firmware_stacks()
+        self._handle_broadcast_message_thread(start_thread=True)
+        time.sleep(1.5) # Wait a while or have a broadcast check
         for binary_file in list_of_binary_files:
             # Make sure the file is opened a binary or hex
             if not binary_file.endswith(".bin") and not binary_file.endswith(".hex"): continue
@@ -251,4 +250,4 @@
                 self._verify_stack_update() # TODO skip if the timeout or another error
 
         # Done with update binary files, stop sending the broadcast message
-        #self._handle_broadcast_message_thread(start_thread=False)
+        self._handle_broadcast_message_thread(start_thread=False)
Index: scripts/update_package_script/utilities.py
===================================================================
diff -u -r4958f2a616031e26b9d0f662b4faca8b28832a53 -r167604cac199c133488d55eb0163e88eadd0e123
--- scripts/update_package_script/utilities.py	(.../utilities.py)	(revision 4958f2a616031e26b9d0f662b4faca8b28832a53)
+++ scripts/update_package_script/utilities.py	(.../utilities.py)	(revision 167604cac199c133488d55eb0163e88eadd0e123)
@@ -7,11 +7,32 @@
 from can.interfaces.socketcan.socketcan import SocketcanBus
 
 class CANMessageListener(can.Listener):
+    """
+    CAN Message Listener
 
+    The class is CAN listener
+    """
     def __init__(self):
+        """
+         CANMessageListener class constructor
+
+        """
         self.raw_can_messages = list()
 
+    def clear_message_list(self):
+        """
+        Publicly accessible method to clear the list of the raw CAN messages.
+
+        @return none
+        """
+        self.raw_can_messages.clear()
+
     def on_message_received(self, msg: can.Message):
+        """
+        Publicly accessible method to receive the raw CAN messages
+
+        @return none
+        """
         self.raw_can_messages.append(msg)
 
 
@@ -92,11 +113,34 @@
         0xD2DFB272, 0xCC03DD33, 0xEF676CF0, 0xF1BB03B1, 0xA9AE0F76, 0xB7726037, 0x9416D1F4, 0x8ACABEB5,
     )
 
+    CRC_LIST = (
+        0, 49, 98, 83, 196, 245, 166, 151, 185, 136, 219, 234, 125, 76, 31, 46,
+        67, 114, 33, 16, 135, 182, 229, 212, 250, 203, 152, 169, 62, 15, 92, 109,
+        134, 183, 228, 213, 66, 115, 32, 17, 63, 14, 93, 108, 251, 202, 153, 168,
+        197, 244, 167, 150, 1, 48, 99, 82, 124, 77, 30, 47, 184, 137, 218, 235,
+        61, 12, 95, 110, 249, 200, 155, 170, 132, 181, 230, 215, 64, 113, 34, 19,
+        126, 79, 28, 45, 186, 139, 216, 233, 199, 246, 165, 148, 3, 50, 97, 80,
+        187, 138, 217, 232, 127, 78, 29, 44, 2, 51, 96, 81, 198, 247, 164, 149,
+        248, 201, 154, 171, 60, 13, 94, 111, 65, 112, 35, 18, 133, 180, 231, 214,
+        122, 75, 24, 41, 190, 143, 220, 237, 195, 242, 161, 144, 7, 54, 101, 84,
+        57, 8, 91, 106, 253, 204, 159, 174, 128, 177, 226, 211, 68, 117, 38, 23,
+        252, 205, 158, 175, 56, 9, 90, 107, 69, 116, 39, 22, 129, 176, 227, 210,
+        191, 142, 221, 236, 123, 74, 25, 40, 6, 55, 100, 85, 194, 243, 160, 145,
+        71, 118, 37, 20, 131, 178, 225, 208, 254, 207, 156, 173, 58, 11, 88, 105,
+        4, 53, 102, 87, 192, 241, 162, 147, 189, 140, 223, 238, 121, 72, 27, 42,
+        193, 240, 163, 146, 5, 52, 103, 86, 120, 73, 26, 43, 188, 141, 222, 239,
+        130, 179, 224, 209, 70, 119, 36, 21, 59, 10, 89, 104, 255, 206, 157, 172
+    )
+
     _SEND_CMD_MAIL_BOX = 0x601
     _BROADCAST_UPDATE_MAIL_BOX = 0x606
-    MSG_ID_FFU_SIGNAL_TD_UPDATE_AVAILABLE = 0xA6
-    MSG_ID_FFu_SIGNAL_DD_UPDATE_AVAILABLE = 0xA7
 
+    _LEAHI_START_MESSAGE_BYTE = 0xA5
+    _LEAHI_SEQ_1_BYTE = 0x1234
+    _LEAHI_SEQ_2_BYTE = 0x34
+    _LEAHI_SIGNAL_TD_UPDATE_AVAILABLE = 0x00A6
+    _LEAHI_SIGNAL_DD_UPDATE_AVAILABLE = 0x00A7
+
     _SHIFT_8_BITS_FOR_BYTE_SHIFT = 8
     _SHIFT_24_BITS = 24
     _SHIFT_BITS_BY_A_NIBBLE = 4
@@ -123,6 +167,7 @@
         self._msg_id_count = 0
         self._msg_sw_update_index = 0
         self._update_mail_boxes = dict()
+        self._leahi_mail_boxes = dict()
         self._msg_ack_nack_status = dict()
         self._total_msg_count = 0
         self._stack = 0
@@ -131,7 +176,7 @@
         self._msg_ack_nack_status[self.UPDATE_MSG_ACK_STATUS_KEY_NAME] = [CanCommStatus.CAN_COMM_NOT_STARTED.value, 0]
         self.file_handle = open(os.path.join(os.getcwd(), 'ack_log.log'), 'w')
 
-        self._prepare_update_mail_boxes(self._update_mail_boxes)
+        self._prepare_update_mail_boxes()
 
         self._can_listener = CANMessageListener()
         self._notifier = can.Notifier(self._can_bus, [self._can_listener])
@@ -156,6 +201,14 @@
         """
         self._msg_ack_nack_status[msg_type][0] = CanCommStatus.CAN_COMM_NOT_STARTED.value
 
+    def clear_can_listener(self):
+        """
+        Publicly accessible method to clear the CAN listener.
+
+        @return none
+        """
+        self._can_listener.clear_message_list()
+
     def send_command_msg(self, cmd: int, stack: int, destination: int):
         """
         Publicly accessible method to send a command message to the bootloader
@@ -227,7 +280,14 @@
         self._get_bootloader_ack_nack_resp(self.UPDATE_MSG_ACK_STATUS_KEY_NAME)
 
     def send_update_available_broadcast_message(self, stop_event, interval: int):
+        """
+        Publicly accessible method to send the update available broadcast message.
 
+        @param stop_event: the stop event thread flag
+        @param interval: broadcast interval
+
+        @return none
+        """
         count = 1
         while not stop_event.is_set():
             count += 1
@@ -237,8 +297,28 @@
             crc_32 = self._get_crc32(can_msg_bytes)
             can_msg_bytes += self._convert_data_to_bytes('<I', crc_32)
             self._send_can_message(self._BROADCAST_UPDATE_MAIL_BOX, can_msg_bytes, '')
+            # Sleep the thread for the define interval
             stop_event.wait(interval)
 
+    def send_update_available_to_firmware_stacks(self):
+        """
+        Publicly accessible method to send update is available message to firmware stacks
+
+        @return none
+        """
+        can_msg_bytes = self._convert_data_to_bytes('<B', self._LEAHI_START_MESSAGE_BYTE)
+        can_msg_bytes += self._convert_data_to_bytes('<H', self._LEAHI_SEQ_1_BYTE)
+
+        for msg_id, mail_box in self._leahi_mail_boxes.items():
+            # Loop through the Leahi mail boxes
+            can_msg_bytes += self._convert_data_to_bytes('<H', msg_id)
+            can_msg_bytes += self._convert_data_to_bytes('<B', 0) # Payload length is 0
+            crc_8 = self._get_crc8(can_msg_bytes[1:])
+            can_msg_bytes += self._convert_data_to_bytes('<B', crc_8)
+            can_msg_bytes += self._convert_data_to_bytes('<B', 0) # Padding the last byte to be an 8-byte frame
+            mail_box_id = mail_box[self._STACK_SEND_UPDATE_MAIL_BOX]
+            self._send_can_message(mail_box_id, can_msg_bytes, '')
+
     ######################## PRIVATE/CLASS/STATIC METHODS ##############################
 
     def _send_can_message(self, mail_box: int, data: bytes, msg_type: str):
@@ -316,13 +396,40 @@
 
         return crc
 
-    def _prepare_update_mail_boxes(self, update_mail_boxes: dict):
+    @classmethod
+    def _get_crc8(cls, message_list: bytes):
+        """
+        Class method to calculate CRC8
 
-        update_mail_boxes[UpdateStacks.STACK_TD.name] = {self._STACK_SEND_UPDATE_MAIL_BOX: 0x603,
-                                                         self._STACK_RCV_RESP_MAIL_BOX: 0x602}
-        update_mail_boxes[UpdateStacks.STACK_DD.name] = {self._STACK_SEND_UPDATE_MAIL_BOX: 0x605,
-                                                         self._STACK_RCV_RESP_MAIL_BOX: 0x604}
+        @param message_list: is a list of integer numbers containing the message
 
+        @return 8-bit CRC
+        """
+        crc = 0
+        for byte in message_list:
+            unsigned_byte = byte ^ crc
+            crc = cls.CRC_LIST[unsigned_byte]
+
+        return crc
+
+    def _prepare_update_mail_boxes(self):
+        """
+        Privately accessible method to prepare the update mailboxes in the dictionaries
+
+        @return none
+        """
+        self._update_mail_boxes[UpdateStacks.STACK_TD.name] = {self._STACK_SEND_UPDATE_MAIL_BOX: 0x603,
+                                                               self._STACK_RCV_RESP_MAIL_BOX: 0x602}
+        self._update_mail_boxes[UpdateStacks.STACK_DD.name] = {self._STACK_SEND_UPDATE_MAIL_BOX: 0x605,
+                                                               self._STACK_RCV_RESP_MAIL_BOX: 0x604}
+
+        self._leahi_mail_boxes[self._LEAHI_SIGNAL_TD_UPDATE_AVAILABLE] = {self._STACK_SEND_UPDATE_MAIL_BOX: 0x041,
+                                                                          self._STACK_RCV_RESP_MAIL_BOX: 0x040}
+
+        # TODO DEFINE THE DD CHANNELS IN LEAHI -> THESE ARE FOR BOOTLOADER
+        #self._leahi_mail_boxes[UpdateStacks.STACK_DD.name] = {self._STACK_SEND_UPDATE_MAIL_BOX: 0x605,
+        #                                                      self._STACK_RCV_RESP_MAIL_BOX: 0x604}
+
     @staticmethod
     def _convert_data_to_bytes(conversion: str, data: int):
         """
@@ -352,7 +459,11 @@
         return converted
 
     def _get_current_message_count(self):
+        """
+        Privately accessible method to get the current message count.
 
+        @return current message count
+        """
         self._msg_id_count = self._msg_id_count + 1 if self._msg_id_count < 0xFFFF else 0
 
         return self._msg_id_count