Core Electronics Forum

Bluetooth range on Pi 4 very limited

It appears that the bluetooth range on the Raspberry Pi 4 is rather limited, dropping off within a few meters in an open space.

Are there any options to extend the bluetooth range on the Pi 4? Would a bluetooth dongle help?

Not sure if the weak signal strength is at the device end, in this case a Mijia Bluetooth Temperature/Humidity Sensor.

Any thoughts would be much appreciated, thanks!

– Jono

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Hmm, that’s not normal - though bluetooth is only good for about 10m line of sight.

RF interference can also decrease the effective range - anything in the 2.4GHz region can have an impact: Microwaves, WiFi, and USB 3 devices have all been known to cause issues with bluetooth, as well as the shielding from anything metal being in the way, such as a metal Pi Case.

What BT device are you using? And what else do you have near it?

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I am using the https://core-electronics.com.au/mijia-bluetooth-temperature-humidity-sensor-with-lcd-display.html.

I am able to read the temperature and humidity data using GitHub - uduncanu/lywsd03mmc: Python library for Xiaomi Mijia LYWSD03MMC sensors, if it is close by.

I have a 2.4/5 GHz WiFi router, which the Pi is connected to (5 GHz), along with all the devices in the house…

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I have the Pi housed in a Argon Neo case, which has a plastic bottom, don’t think it interferes too much, but you never know…

– Jono

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Hi Jono,

The plastic bottom of the Neo case should allow it to still work with BlueTooth, just to help isolate the cause of the issues could you test it again without the Neo case to see if anything changes? That way you can rule the case in or out as a contributing factor.

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If it’s any consolation I have that same case and experience a similar sort of Bluetooth drop-off. Granted, I haven’t tested it without the case, but it might be worth trying it like Trent suggests just for testing. I’m OK with the limited range myself for my purposes.

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Just a quick update and good news.

It does appear that the bluetooth range on the Pi 4 is rather limited, that seems to be the general consensus out there. The Pi Zero W, however, is reported to have an excellent bluetooth range.

The Pi Zero WH arrived today (finally in stock, yay!), and I’m glad to report that it discovered and connected to all the Mijia Bluetooth Temperature/Humidity sensors I have scattered around the house, both inside and just outside the house! Go the mighty tiny Zero!!!

So I’m a happy camper!

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@Jono if you’ve still got your Pi 4 setup, try disabling the ethernet port (I don’t have a Pi 4 myself to test, but this should work I think)

    ip link set eth0 down

There’s also an older article on the Core site here that uses a different method:

My theory as to why this might work is that ethernet on the Pi 4 is actually via USB 3.0 - USB 3.0 can cause some nasty interference with bluetooth devices that really kills the range. Thus disabling the ethernet adapter (and making sure to only be using the USB 2.0 ports and not the blue 3.0 ports) might reduce the interference and improve the range of bluetooth on the Pi 4.

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Very interesting!

I do have the Pi 4 booting off a USB 3 stick at the moment, which is plugged in to the USB 3 for the extra speed. Will experiment with disabling the ethernet port first, then see how I go with not vacating USB 3 port.

Thanks for the heads up @Oliver33!

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No worries, let us know how it goes. It’s a bit of a shot in the dark, but fingers crossed :crossed_fingers:

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