[Gta04-owner] Bluetooth speed

Dr. H. Nikolaus Schaller hns at goldelico.com
Tue Oct 11 12:22:21 CEST 2011


Hi all,
while the first boards are being shipped and we are planning
for the next batch, we identified a detail that we did miss.

It is the UART speed of the Bluetooth interface.

The variant of the Bluetooth chip is pre-configured for
115200 bit/s. And that fits nicely to the maximum speed
of the UART driver of the Linux 2.6.32 kernel.

But newer kernels (after 2.6.34) introduced a new "OMAP UART"
driver, which identifies itself as /dev/ttyO1, /ttyO2 etc. This one
can support much higher speeds.

And since Bluetooth can support up to 700 kbit/s - we have
an artificial limitation through our choice of the UART speed.

There appears to be some trick to increase the speed to 921600 bit/s
reported on the Gumstix wii (the Gumstix Overo uses the same
Bluetooth/WLAN combo chip as the GTA04).

	http://wiki.gumstix.org/index.php?title=Category:How_to_-_bluetooth#Bluetooth_advice_from_Australia

So this may be something for the early adopters to play with.

For the next batch we can simply install chips that are
pre-initialized for 921600 bit/s.

Nikolaus


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