Setting up Wi-Fi in Yocto

Configuring Wi-Fi

A common requirement for embedded devices is Wi-Fi.

However, having a Wi-Fi chip on the board does not automatically mean that Linux will be able to use it.

Several components may be required:

The exact architecture depends on the board and Linux distribution.

Checking the Wi-Fi interface

After Linux boots, first check the available interfaces:

ip link

or:

ifconfig

A wireless interface may appear as:

wlan0

Modern Linux systems can use different predictable interface names, so the actual name may differ.

Scanning for Wi-Fi networks

Depending on the networking tools installed, Wi-Fi networks can be scanned using:

iw dev wlan0 scan

or through higher-level network management tools.

If the wireless interface does not exist, the problem may be at a lower level.

Possible causes include:

• Missing kernel driver
• Missing firmware
• Incorrect device tree
• Hardware not enabled
• Power-management issue
• Incorrect BSP configuration

This is an important debugging principle:

Do not assume a networking problem is a network configuration problem. First verify that the hardware and driver are working.

Connecting using wpa_supplicant

A traditional embedded Linux setup can use wpa_supplicant.

A simplified configuration looks like:

ctrl_interface=/var/run/wpa_supplicant
update_config=1

network={
    ssid="MY_WIFI"
    psk="MY_PASSWORD"
}

Then:

wpa_supplicant \
    -B \
    -i wlan0 \
    -c /etc/wpa_supplicant.conf

After association, an IP address can be requested:

dhclient wlan0

The exact commands depend on the networking stack used by the image.

Debugging Wi-Fi

When Wi-Fi does not work, I normally check the problem from the bottom up.

First:

ip link

Is the interface present?

Then:

dmesg | grep -i wlan

and:

dmesg | grep -i firmware

Then inspect:

iw dev

If the interface exists, check whether it can scan.

Finally check IP configuration:

ip addr

and routing:

ip route

This gives a useful troubleshooting sequence: