Makes general improvements to microcontroller script with imports, er…

…ror handling and some comments.

build/figurines/microcontroller_comms.py

@@ -9,19 +9,22 @@
 
 # =========================== IMPORTS ================================== #
 
-import serial.tools.list_ports
 import threading
 import time
 from time import sleep
-import requests
-import socket
+from json import JSONDecodeError
 import json
 import logging
 
+import serial.tools.list_ports
+import requests
+from serial import SerialException, SerialTimeoutException
 # =========================== GLOBAL VALUES ================================== #
 
 POLL_DELAY = 15
 COM_PORT_PREFIX = "cu.usbmodem"  # usbmodem1101 and usbmodem2101
+MAX_CONNECTION_COUNT = 10
+
 global connect_status, read_state, port, serialPort
 global serial_count  # Optimized counter, used to clear the serial input buffer
 serial_count = 0
@@ -106,8 +109,11 @@ def check_presence(port, interval=0.01):
 
 
 def start_thread():
+    """Starts a thread that checks serial port presence"""
     global port, connect_status
     _LOGGER.info("Starting thread at port %s", port)
+    # target - callable object invoked by the start() or run() command
+    # args - arguments passed to check_presence command
     port_controller = threading.Thread(target=check_presence, args=(port, 0.1))
     port_controller.daemon = True
     port_controller.start()
@@ -120,28 +126,62 @@ def main():
     global port, connect_status
     figurine_status = {}
 
+    connection_count = 0
+
     while True:
+        if connection_count >= MAX_CONNECTION_COUNT:
+            _LOGGER.error("Could not find valid serial connection and timed out, try again")
+            return
+
         if not connect_status:
-            port_device = None 
+            port_device = None
             ports = serial.tools.list_ports.comports()
             for port in ports:
-                if COM_PORT_PREFIX in port.name:
+                _LOGGER.info("Trying port - %s", port.device)
+                if port.name is not None and COM_PORT_PREFIX in port.name:
                     port_device = port[0]
                     break
+            connection_count += 1
             if port_device is not None:
-                initialise_serial(port_device)
-                start_thread()
+                try:
+                    initialise_serial(port_device)
+                except ValueError as e:
+                    _LOGGER.error("Parameter given is out of range")
+                    _LOGGER.debug(e)
+                except SerialException as e:
+                    # SerialException derives from IOError
+                    _LOGGER.error("Device can not be found or configured")
+                    _LOGGER.debug(e)
+
+                try:
+                    start_thread()
+                except RuntimeError as e:
+                    _LOGGER.error("start() method called more than once for same thread object")
+                    _LOGGER.debug(e)
+
             else:
                 connect_status = False
             continue
         if serialPort.is_open:
             try:
-                response = json.loads(
-                    requests.get('http://127.0.0.1:8000/figurines', timeout=5).text
-                )
-                if response != figurine_status:
-                    figurine_status = response
-                    send_to_controller(figurine_status)
+                response_body = requests.get('http://127.0.0.1:8000/figurines', timeout=5).text
+                if response_body is not None:
+                    try:
+                        response = json.loads(response_body)
+                    except JSONDecodeError as e:
+                        _LOGGER.error("Not valid JSON document")
+                        _LOGGER.debug(e)
+                else:
+                    _LOGGER.Error("Got nothing from the api")
+                    continue
+                try:
+                    send_to_controller(response)
+                except SerialTimeoutException as e:
+                    _LOGGER.error("Write timeout")
+                    _LOGGER.debug(e)
+                # if response != figurine_status:
+                #     figurine_status = response
+                #     send_to_controller(figurine_status)
                 sleep(POLL_DELAY)
             except requests.exceptions.ConnectionError as e:
                 _LOGGER.info("Error making HTTP request")