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. On your picoexpander there is a settings.toml file. Open this file in a text-editor. Unfortunately you can not use Mu Editor to do this.

  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).

CIRCUITPY_WIFI_SSID = "network-name"
CIRCUITPY_WIFI_PASSWORD = "network-password"

  1. Save your settings.toml file.

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

  • import time
import wifi
import socketpool
import ipaddress
import os

print("Raspberry Pi Pico 2 W Connection Test")
print("*" * 40)

print("\nScanning for available networks...")
network_list = []

# Scan for networks (native method)
# start_scanning_networks returns an iterable, so we loop through it
for network in wifi.radio.start_scanning_networks():
    if network.ssid: # Filter out hidden/empty SSIDs
        network_list.append(network.ssid)
wifi.radio.stop_scanning_networks()

# Check if your target SSID was found in the scan
if os.getenv("CIRCUITPY_WIFI_SSID") not in network_list:
    print(os.getenv("CIRCUITPY_WIFI_SSID"), "not found.\nAvailable networks:", network_list)
    # In CircuitPython, SystemExit doesn't always stop the code effectively in IDEs,
    # but we will keep it to match your logic.
    raise SystemExit(0)

print(os.getenv("CIRCUITPY_WIFI_SSID"), "found. Connecting...")

# Connection Loop
while not wifi.radio.ipv4_address:
    try:
        # Connect to the WiFi network
        wifi.radio.connect(os.getenv("CIRCUITPY_WIFI_SSID"), os.getenv("CIRCUITPY_WIFI_PASSWORD"))
    except Exception as e:
        print("\nUnable to establish connection. Are you using a valid password?")
        print("Error message:", e, "\nRetrying...")
        time.sleep(2) # Short pause before retry
        continue

print("Connected! IP address:", wifi.radio.ipv4_address)

# Create a SocketPool to resolve domain names (DNS)
pool = socketpool.SocketPool(wifi.radio)

while True:
    print("\nPinging google.com...")
    try:
        # 1. Resolve domain name to IP address
        # getaddrinfo returns a list of info; we grab the first IP address found
        info = pool.getaddrinfo("google.com", 80)
        google_ip_str = info[0][4][0]
        google_ip = ipaddress.ip_address(google_ip_str)
        
        # 2. Ping the IP address
        # wifi.radio.ping returns time in seconds (float) or None if timeout
        response_s = wifi.radio.ping(google_ip)
        
        if response_s is not None:
            # Convert seconds to milliseconds to match your original format
            ms = response_s * 1000
            print(f"Ping successful. Response time: {ms:.1f} ms")
        else:
            print("Ping timed out.")
            
    except Exception as e:
        print("Ping failed with error:", e)

    time.sleep(5)

  • import board
import busio
import time
import digitalio
from adafruit_esp32spi import adafruit_esp32spi
import os

# 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 os.getenv("CIRCUITPY_WIFI_SSID") not in network_list:
    print(os.getenv("CIRCUITPY_WIFI_SSID"), "not found.\nAvailable networks:", network_list) 
    raise SystemExit(0)
         
print(settings["ssid"], "found. Connecting...")
while not esp.is_connected:
    try:
        esp.connect_AP(os.getenv("CIRCUITPY_WIFI_SSID"), os.getenv("CIRCUITPY_WIFI_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:

    • 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.

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