What you'll learn

Joining WiFi with network.WLAN in station mode
Waiting with a timeout instead of forever
Raising an error when something fails
Putting a job in a function you can call again

Difficulty: Beginner
Time: About 10 minutes
Board: Raspberry Pi Pico W
Parts: 1

How it works

Nothing is wired. The board joins a WiFi network as a client. Here that is Mokxi's simulated access point, named Mokxi-Lab with the password breadboard. At home, you would put in your own network's name and password.

The script calls connect, which waits up to ten seconds for the link. When it succeeds, the script prints the IP address the router handed out. If it times out, the script stops with an error saying it could not join.

Parts list

1 part, plus the jumper wires. They retail for about $6; on Mokxi they're free.

1 × Raspberry Pi Pico W

Kits that can build it

These 2 starter kits have every part in the circuit. Each kit's page lists what else it can build.

The code

The MicroPython code exactly as the editor opens it. Change a line there and press Run: the board runs it on the official MicroPython firmware, with nothing to compile.

main.py · Raspberry Pi Pico W

# Access to the network: join WiFi and print the address the router
# gives the board. Here the board joins Mokxi's simulated access point,
# whose name and password are the board's WiFi properties; at home, put
# in your own network's.
import network
import time

SSID = "Mokxi-Lab"
PASSWORD = "breadboard"

def connect(ssid, password):
    wlan = network.WLAN(network.STA_IF)
    wlan.active(True)
    wlan.connect(ssid, password)
    for _ in range(20):                    # give it ten seconds
        if wlan.isconnected():
            return wlan.ifconfig()[0]
        time.sleep_ms(500)
    raise RuntimeError("could not join " + ssid)

print("Connecting to", SSID)
ip = connect(SSID, PASSWORD)
print("Connected, IP address", ip)
while True:
    time.sleep(1)

Code walkthrough

The key functions of the sketch, and what each one does.

`connect` main.py

Turns on the station interface and starts joining with wlan.connect. It then checks up to 20 times, half a second apart, which is ten seconds. If isconnected turns true it returns the IP address. If not, it raises a RuntimeError naming the network.

def connect(ssid, password):
    wlan = network.WLAN(network.STA_IF)
    wlan.active(True)
    wlan.connect(ssid, password)
    for _ in range(20):                    # give it ten seconds
        if wlan.isconnected():
            return wlan.ifconfig()[0]
        time.sleep_ms(500)
    raise RuntimeError("could not join " + ssid)

Troubleshooting

The usual mistakes with this circuit, and the fix for each.

It stops with could not join This project
Check that SSID and PASSWORD match the network exactly. In Mokxi they are the board's WiFi properties.
Pins are powered from 5 V, or a 5 V signal goes into a GPIO. The RP2040 pins are 3.3 V only and are not 5 V tolerant. Raspberry Pi Pico W
Power the board from VBUS or VSYS at 5 V, but keep GPIO signals at 3.3 V. Use a level shifter or a divider for 5 V parts.
WiFi code fails to connect, or the on-board LED code does nothing. The LED on the Pico W is not on GP25 like on the plain Pico. Raspberry Pi Pico W
Use the board's LED_BUILTIN name so the library drives it through the WiFi chip. Join a 2.4 GHz network only, with the right SSID and password, and wait for the link before sending.