I'm working on a project using the M5 Dial with MicroPython and UIFlow 2.0, and I'm encountering an issue where adding Wi-Fi and MQTT code causes my RFID reader to timeout and throw exceptions. When I run the RFID code alone, it works perfectly, but when I include the Wi-Fi connection and MQTT functionalities, the RFID reader starts experiencing problems.

Problem Description:

• RFID Reader Works Alone: The RFID reader functions correctly when running only the RFID-related code.

• Issue When Adding Wi-Fi and MQTT: Including Wi-Fi connection code and MQTT client causes the RFID reader to throw timeout errors and sometimes leads to the device restarting.

• Error Messages:

  Exception during RFID operation: [Errno 116] ETIMEDOUT
  Traceback (most recent call last):
    File "<stdin>", line XX, in main_loop
    File "unit/rfid.py", line X, in is_new_card_present
    File "driver/mfrc522/__init__.py", line XXX, in picc_request_a
    ... (additional traceback lines)
  OSError: [Errno 116] ETIMEDOUT
  

What I'm Doing:

• RFID Reader: Reading RFID tags using the built-in RFID unit connected via the M5Stack PORT.B (I2C).
• Wi-Fi Connection: Connecting to a Wi-Fi network using the built-in Wi-Fi module.
• MQTT Client: Publishing and subscribing to topics using the umqtt.simple library.
• Asynchronous Tasks: Using uasyncio to handle asynchronous operations, including reading RFID tags and maintaining MQTT connections.

Code Snippets:

Here are the relevant parts of my code:

• RFID Reading Loop:

  async def main_loop():
      global rfid
      while True:
          try:
              if rfid:
                  # Attempt to detect a card
                  card_present = rfid.is_new_card_present()
                  if card_present:
                      # Read card UID
                      card_uid = rfid.read_card_uid()
                      # Process the card UID
              else:
                  print("RFID object is None, attempting to reinitialize")
                  try:
                      rfid = RFID()
                      print("RFID reinitialized")
                  except Exception as e:
                      print(f"Error reinitializing RFID: {e}")
          except Exception as e:
              print(f"Exception in main_loop: {e}")
          await asyncio.sleep(0.1)
  

• Wi-Fi Connection Function:

  async def connect_wifi():
      global wlan
      wlan = network.WLAN(network.STA_IF)
      wlan.active(True)
      await asyncio.sleep(1)
      wlan.connect('Your_SSID', 'Your_Password')
      while not wlan.isconnected():
          print('Waiting for Wi-Fi connection...')
          await asyncio.sleep(1)
      print('Wi-Fi Connected')
  

• MQTT Connection Function:

  async def connect_mqtt():
      global mqtt_client
      mqtt_client = MQTTClient('client_id', MQTT_BROKER, port=MQTT_PORT, user=MQTT_USER, password=MQTT_PASSWORD)
      mqtt_client.connect()
      print('MQTT Connected')
  

• Initialization Function:

  async def setup():
      global rfid
      M5.begin()
      # Initialize RFID
      try:
          rfid = RFID()
          print("RFID initialized")
      except Exception as e:
          print(f"Error initializing RFID: {e}")
          rfid = None
      # Connect to Wi-Fi
      await connect_wifi()
      # Connect to MQTT
      await connect_mqtt()
  

Observations:

• Possible Resource Conflict: I suspect there might be a resource conflict between the RFID reader and the Wi-Fi module when both are active.
• Task Scheduling Issues: The asynchronous tasks for Wi-Fi, MQTT, and RFID might be interfering with each other, causing timeouts in RFID operations.
• RFID Timeout Only When Wi-Fi and MQTT Are Active: If I remove the Wi-Fi and MQTT code, the RFID reader works without any issues.

What I've Tried:

1. Using Asyncio Locks: Implemented asyncio.Lock() around hardware access code to prevent resource conflicts.

   # Initialize a lock
   lock = asyncio.Lock()
   
   # In RFID operation
   async with lock:
       # RFID read code
   
   # In Wi-Fi and MQTT operations
   async with lock:
       # Wi-Fi and MQTT code
   

2. Adjusting Task Frequencies: Increased sleep durations in non-critical tasks to reduce CPU load and potential interference.

3. Ensuring Proper Initialization: Made sure all variables and hardware components are properly initialized and declared as global where necessary.

4. Simplifying the Code: Tested the code by removing the Wi-Fi signal strength monitoring task, but the issue still persists when MQTT is active.

Questions:

1. Resource Contention: Could the RFID reader and Wi-Fi module be conflicting due to shared hardware resources? If so, how can I effectively manage this conflict?

2. Task Synchronization: Is there a recommended way to synchronize tasks involving RFID, Wi-Fi, and MQTT to prevent interference?

3. Hardware Limitations: Are there known limitations with the M5Stack Core2 when using RFID and Wi-Fi/MQTT simultaneously?

4. Alternative Approaches: Suggest some other methods to handle such scnarios

Additional Information:

• Device: M5Stack Core2
• Programming Language: MicroPython
• RFID Reader Connection: Built-in RFID unit connected via I2C (PORT.B)
• Wi-Fi Module: Built-in Wi-Fi module
• MQTT Library: Using umqtt.simple
• Asyncio Version: Using uasyncio for asynchronous operations

Any insights or suggestions would be greatly appreciated! I'm looking for guidance on how to resolve this issue so that I can use RFID, Wi-Fi, and MQTT together without conflicts.

Thank you!