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Session 1: Wi-Fi Basics in MicroPython

Synopsis

Covers station mode setup, connecting to wireless networks, IP configuration, and the practical constraints of networking on a microcontroller.

Session Content

Session 1: Wi-Fi Basics in MicroPython

Session Overview

Duration: ~45 minutes
Audience: Python developers with basic programming knowledge
Platform: Raspberry Pi Pico 2 W
IDE: Thonny
Language: MicroPython

Learning Outcomes

By the end of this session, learners will be able to: - Set up Thonny for MicroPython development on the Pico 2 W - Connect the Pico 2 W to a Wi-Fi network - Retrieve and display network information - Understand the basics of Wi-Fi-related MicroPython APIs - Write a simple script that checks Wi-Fi connection status

Prerequisites

  • Raspberry Pi Pico 2 W
  • USB cable for power and data
  • Wi-Fi network name (SSID) and password
  • Thonny installed on a computer
  • MicroPython firmware for Raspberry Pi Pico 2 W

Development Environment Setup

1) Install Thonny

  • Download and install Thonny from: https://thonny.org
  • Launch Thonny

2) Install MicroPython firmware on the Pico 2 W

  1. Hold BOOTSEL while connecting the Pico 2 W to USB.
  2. Copy the appropriate MicroPython UF2 firmware to the Pico drive.
  3. The board will reboot automatically.

3) Configure Thonny

  • Open Tools > Options > Interpreter
  • Select:
  • Interpreter: MicroPython (Raspberry Pi Pico)
  • Port: Auto-detect or the Pico 2 W serial port
  • Click OK

4) Verify connection

In the Thonny shell, run:

print("Hello, Pico 2 W!")

Expected output:

Hello, Pico 2 W!

Theory: Wi-Fi on the Pico 2 W

What is Wi-Fi in MicroPython?

The Pico 2 W includes wireless networking hardware that can be controlled using the network module in MicroPython. This module lets you: - Enable the wireless interface - Connect to a local access point - Check connection status - Read network configuration such as IP address

Key Concepts

  • Station mode (STA_IF): The Pico connects to an existing Wi-Fi network.
  • Access point mode (AP_IF): The Pico creates its own Wi-Fi network.
  • DHCP: The router typically assigns the Pico an IP address automatically.
  • SSID: The Wi-Fi network name.
  • Password: Network security credential.

Common Wi-Fi tasks

  • Activating Wi-Fi
  • Scanning for available networks
  • Connecting to a router
  • Waiting for connection
  • Checking IP configuration

Hands-On Exercise 1: Connect to Wi-Fi

Goal

Connect the Pico 2 W to a Wi-Fi network and display the assigned IP address.

Code

Create a new file in Thonny and save it as main.py on the Pico.

import network
import time

# Replace these with your Wi-Fi credentials
SSID = "YOUR_WIFI_NAME"
PASSWORD = "YOUR_WIFI_PASSWORD"

# Create a station interface (connect to an existing Wi-Fi network)
wlan = network.WLAN(network.STA_IF)

# Activate the Wi-Fi interface
wlan.active(True)

print("Connecting to Wi-Fi...")

# Start the connection process
wlan.connect(SSID, PASSWORD)

# Wait for the connection to complete
timeout = 15
start_time = time.time()

while not wlan.isconnected():
    if time.time() - start_time > timeout:
        print("Connection timed out.")
        break
    print("Waiting for connection...")
    time.sleep(1)

# Show network details if connected
if wlan.isconnected():
    print("Connected successfully!")
    print("Network config:", wlan.ifconfig())
else:
    print("Not connected.")

Expected Output

Connecting to Wi-Fi...
Waiting for connection...
Waiting for connection...
Connected successfully!
Network config: ('192.168.1.42', '255.255.255.0', '192.168.1.1', '192.168.1.1')

Notes

  • Replace YOUR_WIFI_NAME and YOUR_WIFI_PASSWORD with your actual credentials.
  • If the connection fails, verify the SSID/password and ensure the Pico 2 W is within range.

Hands-On Exercise 2: Scan for Nearby Networks

Goal

List nearby Wi-Fi networks and their signal strengths.

Code

import network

# Enable station interface
wlan = network.WLAN(network.STA_IF)
wlan.active(True)

print("Scanning for networks...")

# Scan returns a list of tuples with network details
networks = wlan.scan()

for net in networks:
    ssid = net[0].decode("utf-8")
    bssid = ":".join("{:02x}".format(b) for b in net[1])
    channel = net[2]
    rssi = net[3]
    security = net[4]
    hidden = net[5]

    print("SSID:", ssid)
    print("  BSSID:", bssid)
    print("  Channel:", channel)
    print("  Signal (RSSI):", rssi)
    print("  Security:", security)
    print("  Hidden:", hidden)
    print("-" * 30)

Expected Output

Scanning for networks...
SSID: HomeWiFi
  BSSID: 12:34:56:78:9a:bc
  Channel: 6
  Signal (RSSI): -48
  Security: 3
  Hidden: False
------------------------------

Hands-On Exercise 3: Check Connection Status Repeatedly

Goal

Create a script that checks whether the Pico remains connected to Wi-Fi.

Code

import network
import time

SSID = "YOUR_WIFI_NAME"
PASSWORD = "YOUR_WIFI_PASSWORD"

wlan = network.WLAN(network.STA_IF)
wlan.active(True)
wlan.connect(SSID, PASSWORD)

print("Monitoring Wi-Fi connection...")

for i in range(10):
    if wlan.isconnected():
        print("Check", i + 1, ": Connected")
        print("IP:", wlan.ifconfig()[0])
    else:
        print("Check", i + 1, ": Not connected")
    time.sleep(2)

Expected Output

Monitoring Wi-Fi connection...
Check 1 : Connected
IP: 192.168.1.42
Check 2 : Connected
IP: 192.168.1.42
...

Mini-Challenge: Build a Wi-Fi Status Script

Modify the connection script so that it: - Prints "Wi-Fi OK" when connected - Prints "Wi-Fi disconnected" when not connected - Retries connection every 5 seconds if disconnected

Starter Template

import network
import time

SSID = "YOUR_WIFI_NAME"
PASSWORD = "YOUR_WIFI_PASSWORD"

wlan = network.WLAN(network.STA_IF)
wlan.active(True)

while True:
    if not wlan.isconnected():
        print("Trying to connect...")
        wlan.connect(SSID, PASSWORD)
        time.sleep(5)
    else:
        print("Wi-Fi OK | IP:", wlan.ifconfig()[0])
        time.sleep(5)

Common Issues and Troubleshooting

1) Wrong SSID or password

  • Double-check spelling and case sensitivity
  • Ensure the router is broadcasting the correct network name

2) Weak signal

  • Move the Pico closer to the router
  • Reduce interference from walls or devices

3) Unsupported Wi-Fi settings

  • Some networks use settings that may not work well with embedded devices
  • Prefer standard WPA/WPA2 networks

4) No serial output in Thonny

  • Check the correct interpreter is selected
  • Reconnect the board and restart Thonny

Key Takeaways

  • The network module is the main MicroPython interface for Wi-Fi
  • Use network.WLAN(network.STA_IF) to join a Wi-Fi network
  • wlan.active(True) enables the radio
  • wlan.connect(ssid, password) starts the connection
  • wlan.isconnected() confirms connection status
  • wlan.ifconfig() shows IP and network settings

Review Questions

  1. What does STA_IF mean?
  2. Why do we call wlan.active(True) before connecting?
  3. What information does ifconfig() return?
  4. How can you tell if the Pico is connected to Wi-Fi?
  5. What should you check if the connection fails?

Suggested Next Step

In the next session, use this Wi-Fi connection setup to make HTTP requests and connect the Pico 2 W to internet services.

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