Yellow and external wifi antenna | Home Assistant | Page 1

sharp raft Dec 3, 2024, 12:13 PM

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The CM4 uses a small built-in antenna by default, but has a connector for an external antenna. On a Raspbian, you'd have to tweak dtparam in config.txt to switch to the external antenna, how to do the same on Yellow?

rustic sable Dec 3, 2024, 12:25 PM

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The same way. You can edit that file via the serial console. But I haven't really verified, if it reaĺly transmits via the external antenne. With the small external PCB antenna I didn't experience any benefits. I don't use the onboard WiFi or BT though.

sharp raft Dec 3, 2024, 1:34 PM

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Ah, I see now, SSH goes inside a Docker container, so no wonder there's no boot stuff. 😊 Talking about verify, how would you verify which antenna is actually used?

rustic sable Dec 3, 2024, 1:54 PM

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In the serial console you could try the command cat /sys/kernel/debug/gpio | grep ant - ant2 would be the external antenna.
That would be an indication it is working. I guess, measuring radio emissions would be the 100% accurate variant.

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But I don't have an oscilloscope to look, if the external antenna transmits anything.

sharp raft Dec 3, 2024, 7:07 PM

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# cat /sys/kernel/debug/gpio | grep ant
 gpio-573 (ANT1                |ant1                ) out lo
 gpio-577 (ANT2                |ant2                ) out hi

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Maybe I can check it with some aluminium foil to shield the signal, should cause the iBeacon to report a longer distance.

#Yellow and external wifi antenna