Part 3 - Connect to a WiFi Network

To connect your microcontroller to a network, you must provide a network name (SSID) and password. However, directly using sensitive data like WiFi passwords in your code is risky. Therefore, creating a separate file to hold your personal keys and passwords outside your code.py file is a good idea. This way, you can share your code without revealing sensitive data to others.

1. Begin by clicking the + icon labeled New in the top toolbar of Mu Editor.

2. Copy and paste the following code to the new file, replacing network-name with the name of your WiFi network and network-passwd with your network’s password (or the iPSK generated during part two when connecting to TUD-facility).

settings = {
    "ssid": "network-name",
    "password": "network-passwd"
}

1. Click the Save button in the toolbar and save the file on your CIRCUITPY drive using the name settings.py.

2. Enter your code.py file and replace the code you wrote in part one with the code below, then hit Save.

• PicoExpander
• BitsyExpander

• print("hello world")
  

• import board
  import busio
  import time
  import digitalio
  from adafruit_esp32spi import adafruit_esp32spi
  
  # Get WiFi details from your settings.py file
  from settings import settings
  
  # Define the pins used by the BitsyExpander's ESP32 WiFi module
  esp32_cs = digitalio.DigitalInOut(board.D9)
  esp32_ready = digitalio.DigitalInOut(board.D11)
  esp32_reset = digitalio.DigitalInOut(board.D12)
  spi = busio.SPI(board.SCK, board.MOSI, board.MISO)
  
  # Initialize the ESP32 WiFi module
  esp = adafruit_esp32spi.ESP_SPIcontrol(spi, esp32_cs, esp32_ready, esp32_reset)
  
  if esp.status == adafruit_esp32spi.WL_IDLE_STATUS:
      print("\nESP32 WiFi Module found.")
      print("Firmware version:", str(esp.firmware_version, "utf-8"))
      print("*" * 40)
  
  print("\nScanning for available networks...\n")
  network_list = [str(ap["ssid"], "utf-8") for ap in esp.scan_networks()]    
  if settings["ssid"] not in network_list:
      print(settings["ssid"], "not found.\nAvailable networks:", network_list) 
      raise SystemExit(0)
           
  print(settings["ssid"], "found. Connecting...")
  while not esp.is_connected:
      try:
          esp.connect_AP(settings["ssid"], settings["password"])
      except (RuntimeError, ConnectionError) as e:
          print("\nUnable to establish connection. Are you using a valid password?")
          print("Error message:", e, "\nRetrying...")
          continue
           
  print("Connected! IP address:", esp.pretty_ip(esp.ip_address))
            
  while True:
      print("\nPinging google.com...")
      response = esp.ping("google.com")
      print("Ping successful. Response time:", response, "ms")
      time.sleep(5)
  

1. Open Mu’s Serial Monitor to verify that the microcontroller successfully connects to the chosen network and can get a response from google.com.

2. Note the differences from the code you encountered in part one of this tutorial:

   • An import statement for your newly created settings.py file has been added. This gives the code access to the network name (SSID) and password.
   • The network scan has been moved out of the while True: loop and is performed once before entering the loop.
   • The code verifies the network you configured is available and waits for the successful establishment of a connection.
   • The content of the while True: loop has been replaced: It now pings google.com and reports the response time. This confirms internet connectivity for your microcontroller.

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Your microcontroller is now ready for connecting to the internet or even other microcontroller’s! Good luck with your connected projects ;-)