Skip to main content
Logo
Overview

How to Configure Wi-Fi on a Raspberry Pi 5 Running Minimal Yocto

Jian De (Jaydon) Jian De (Jaydon)
March 5, 2026
3 min read
Raspberry Pi
Yocto
Networking
Linux

Navigating networking on a minimal Linux distribution can sometimes feel like solving a puzzle. If you are running a custom Yocto image on a Raspberry Pi 5 and trying to get your Wi-Fi working without the luxury of NetworkManager, you might run into a few roadblocks.

When you check your network interfaces using networkctl and see that wlan0 is sitting stubbornly in an “off” and “unmanaged” state, it’s a clear sign that the default networking mechanisms aren’t kicking in as expected. Here is a comprehensive guide to understanding why this happens and how to fix it using wpa_supplicant and systemd-networkd.

The Problem: The “Yocto Factor”

In a standard Raspberry Pi OS setup, NetworkManager typically handles everything seamlessly out of the box. However, in a custom, minimal Yocto build, wpa_supplicant might be running via D-Bus (often denoted by the -u flag in its process string) but without a dedicated configuration file or a defined control interface.

Because of this missing link between the hardware and the daemon, running wpa_cli -i wlan0 to interactively connect to a network results in an error like:

Could not connect to wpa_supplicant: wlan0 - re-trying

This means wpa_cli is essentially shouting into a void. Let’s manually bridge that gap.

1. Create the Missing Configuration

We need to provide wpa_supplicant with a configuration file that explicitly defines the control interface socket required by wpa_cli.

Create the directory and the configuration file:

Terminal window
sudo mkdir -p /etc/wpa_supplicant
sudo tee /etc/wpa_supplicant/wpa_supplicant.conf > /dev/null <<EOF
ctrl_interface=/var/run/wpa_supplicant
ctrl_interface_group=0
update_config=1
EOF
  • ctrl_interface: Creates the socket that wpa_cli uses to connect.
  • update_config=1: Allows wpa_cli to save new networks directly back to this file.

2. Bind wpa_supplicant to the Interface

The existing wpa_supplicant service, managed by systemd, is likely running generally without being bound to the wlan0 interface. We need to kill that process, bring the wireless interface up at the kernel level, and restart the daemon manually.

Terminal window
# Stop the D-Bus version from running
sudo systemctl stop wpa_supplicant


# Force wlan0 up at the kernel level
sudo ip link set wlan0 up


# Start wpa_supplicant manually, linking it to the config and interface
sudo wpa_supplicant -B -i wlan0 -c /etc/wpa_supplicant/wpa_supplicant.conf
Tip

The -B flag runs the process in the background, -i specifies the interface, and -c points to the new configuration file we just made.

3. Connect via wpa_cli

Now that the daemon is explicitly watching wlan0 and has a control socket at /var/run/wpa_supplicant, wpa_cli will work as expected:

Terminal window
sudo wpa_cli -i wlan0

Once inside the interactive prompt (>), you can scan and connect to your network:

> scan
> scan_results
> add_network
0
> set_network 0 ssid "Your_Network_Name"
> set_network 0 psk "Your_Password"
> enable_network 0
> save_config
> quit

4. Make it Persistent with systemd-networkd

Even after successfully connecting to your Wi-Fi network, networkctl may still report the interface as unmanaged. This happens because systemd-networkd doesn’t automatically know it should manage IP assignment for this link.

To fix this and ensure the lifecycle is managed correctly on subsequent reboots, create a .network profile to handle DHCP:

Terminal window
sudo tee /etc/systemd/network/25-wlan0.network > /dev/null <<EOF
[Match]
Name=wlan0


[Network]
DHCP=yes
EOF

Restart the network manager to apply the changes:

Terminal window
sudo systemctl restart systemd-networkd

Your wlan0 interface should now be properly configured, connected, and assigned an IP address!

Troubleshooting: “Failed to initiate sched scan”

While working through these steps, checking your systemctl logs (sudo systemctl status wpa_supplicant) might reveal the following error:

wlan0: Failed to initiate sched scan

This commonly occurs if the interface is soft-blocked by a software switch or if there are issues with power saving modes affecting the Wi-Fi chip.

To resolve this:

  1. Try disabling power management for the interface to see if scanning resumes:
    Terminal window
    sudo iw dev wlan0 set power_save off
  2. Double-check that your radio is not blocked using rfkill:
    Terminal window
    sudo rfkill list
    sudo rfkill unblock wifi

By manually defining the control interface for wpa_supplicant and tying IP configuration to systemd-networkd, you can successfully tame the Wi-Fi on a custom Yocto build for the Raspberry Pi 5. Happy tinkering!

References