Hi all,
I have a couple CM4's setup running a simultaneous WiFi AP and Client. The AP is the "primary" connection and comes up first to allow a user to connect to the CM4 and control it. The WiFi is a "secondary" optional connection to let the CM4 connect to the internet for updates and other good stuff. While this setup works and provides good results (after working through some kinks with latency issues) it is limited to operating the AP and Station on the same channel. This means that if the local network is not on the same channel as the AP then the AP needs to be restarted with a new config to run on the same channel.
While this works it feels clunky and leaves a big gap in the connection to the device (30-50s while the AP is restarted). I looked into switching the AP channel dynamically (using chan_switch) although this fails due to missing support for CSA (iw phy shows no channel_switch command or anything mentioning that).
Is this a hardware/firmware limitation with the BCM4345/6? Has anyone figured any workarounds/patches to get channel switch support on RPi's WiFi chipset?
Software setup:
OS:
- buildroot raspberry_pi4_defconfig (+networking packages). Also tested with Raspbian.
AP:
- dnsmasq
- hostapd
Client:
- udhcpc
- wpa_supplicant
For those interested here's a good guide on how to do setup a WiFi AP+Client: https://imti.co/iot-wifi/#legacy-instru ... manual-way)
I have a couple CM4's setup running a simultaneous WiFi AP and Client. The AP is the "primary" connection and comes up first to allow a user to connect to the CM4 and control it. The WiFi is a "secondary" optional connection to let the CM4 connect to the internet for updates and other good stuff. While this setup works and provides good results (after working through some kinks with latency issues) it is limited to operating the AP and Station on the same channel. This means that if the local network is not on the same channel as the AP then the AP needs to be restarted with a new config to run on the same channel.
While this works it feels clunky and leaves a big gap in the connection to the device (30-50s while the AP is restarted). I looked into switching the AP channel dynamically (using chan_switch) although this fails due to missing support for CSA (iw phy shows no channel_switch command or anything mentioning that).
Is this a hardware/firmware limitation with the BCM4345/6? Has anyone figured any workarounds/patches to get channel switch support on RPi's WiFi chipset?
Software setup:
OS:
- buildroot raspberry_pi4_defconfig (+networking packages). Also tested with Raspbian.
AP:
- dnsmasq
- hostapd
Client:
- udhcpc
- wpa_supplicant
For those interested here's a good guide on how to do setup a WiFi AP+Client: https://imti.co/iot-wifi/#legacy-instru ... manual-way)
Statistics: Posted by warmpi — Mon Jan 06, 2025 6:55 pm
