A Pi3 Bluetooth Speaker Problem -SOLVED!

I have a Kitchen Pi project that aesthetics and usability dictate using both Wifi and a Bluetooth Speaker in conjunction with a Chromium Browser.

This is a recipe for disaster with a Pi3 setup.

a) Chromium is both a memory and an I/O hog

b) The integrated Bluetooth and Wifi on a Pi3 are not usable as they share common interfaces, and this appears to be buggy

c) After a period of time the Wifi will crash out, bringing down the Bluetooth in an uncorrectable buffer underrun.

Three measures are needed to fix these issues:

a) Chromium itself will cause BlueAlsa buffer underruns when using an SD card. Simply replacing the SD card with a USB stick helps but not enough. The only real solution to this part of the problem is to use a cheap SSD (64GB is more than enough for most purposes). This addition also avoids the early failure of the SD card caused by Chromium’s  high volume of cache writes.

b) Turn off either the onboard Bluetooth or the onboard Wifi and replace with a USB dongle. To do this a simple addition to /boot/config.txt is all that is required using one of the following:

dtoverlay=pi3-disable-wifi
dtoverlay=pi3-disable-bt

c) Wifi crashing is more contentious as many dispute the logic of why the solution works. Snake oil is one phrase that has been used. It appears that the cause is somewhere in the wlan0 kernel code for wlan power saving, and the cure is to turn off power saving at the source by adding iwconfig wlan0 power off  to /etc/rc.local:

The snake oil comment comes from some bloggers as the Pi turns off power management at kernel level. However, this patch is probably continually active and consumes too many clock cycles which consequently results in the Bluetooth Speaker not being ‘fed’ fast enough. This causes Bluetooth underruns/crashes. The etc/local addition by-passes  the buggy kernel patch.