[How to do instruction] Pi Zero 2 W: Fix choppy bluetooth playback (updated firmware package now available)

[jenzd]

Update: The Zero 2 W bluetooth issue is finally fixed in Moode version 8.3.6 (fresh install) which contains an updated version of the package firmware-brcm80211 (1:20230210-5~bpo11+1+rpt1). For older Moode versions you can run "sudo apt update" followed by "sudo apt install firmware-brcm80211" to solve the issue. No need to follow the guide anymore.

Many users of the Raspberry Pi Zero 2 W (including myself) have experienced choppy audio playback using its internal bluetooth adapter to connect to a speaker/headset. Fortunately a Support thread started by @citro recently came up with a solution (https://moodeaudio.org/forum/showthread.php?tid=4937).

The problem turns out to be caused by internal WLAN and bluetooth interfering with each other and can easily be fixed (or at least greatly improved) by adding coexistence parameters to a firmware configuration file (https://github.com/RPi-Distro/firmware-n.../issues/33). Interestingly the same coexistence parameters have already been in place for virtually all other Raspberry Pi variants - just the Zero 2 W was missing. Note also that the fix has already been added to the source of the respective Pi OS firmware package firmware-brcm80211 (see https://github.com/RPi-Distro/firmware-n...80211/brcm). So the issue should automatically be fixed in a future upgrade of Raspberry Pi OS.


The following guide shows how to fix the bluetooth settings in Moode already today (and spares you the time to browse through the quite long original thread):

1) After logging into Moode via ssh, first check which chip variant your 2 W is using (there are two versions with separate configuration files):

Code:

dmesg | grep brcmfmac43436

This shows either "using brcm/brcmfmac43436s-sdio for chip BCM43430/1" or "using brcm/brcmfmac43436-sdio for chip BCM43430/2".

2) Open the respective firmware configuration file in an editor (e.g. nano):

Code:

# For chip variant BCM43430/1 run
sudo nano /lib/firmware/brcm/brcmfmac43436s-sdio.txt

# For chip variant BCM43430/2 run
sudo nano /lib/firmware/brcm/brcmfmac43436-sdio.txt

3) Add the following lines at the end of the firmware configuration file (same parameters for both variants):

Code:

# Improved Bluetooth coexistence parameters
btc_mode=1
btc_params8=0x4e20
btc_params1=0x7530

4) Finally reboot:

Code:

sudo reboot

Bluetooth audio transmission should be clean now (yet at the cost of reduced WLAN throughput while there is bluetooth traffic).


Best regards
Jens