OESF Portables Forum

Everything Else => General Support and Discussion => Zaurus General Forums => Archived Forums => Accessories => Topic started by: clofland on July 29, 2005, 11:46:42 am

Title: Bluetooth Speed
Post by: clofland on July 29, 2005, 11:46:42 am

When doing a PPP connection over a bluetooth card, the connection appears to be limitted to 460800, though most CF Bluetooth cards can support up to 921600.

Has anyone looked into this, or am I confused?

I found this web site the references the problem with a kernel patch, but I don't think it applies to the Z:

http://www.hpl.hp.com/personal/Jean_Tourri...Brainboxes.html (http://www.hpl.hp.com/personal/Jean_Tourrilhes/bt/Brainboxes.html)

Any ideas? It seems a shame to limit the bluetooth PPP connection by this. I belive my PAN connections attain speeds above the 460800 level, but I could be meassuring wrong and maybe that is the limit PAN hits too?

Title: Bluetooth Speed
Post by: speculatrix on August 09, 2005, 05:27:09 pm

This is working from my memory of such devices a number of years ago...

these are parallel I/O devices, which means although they can appear as serial devices, there's actually no serial processing involved at the host interface, they just emulate a serial modem. The over-the-air interface is a serial protocol, however, there's a lot of overheads of error correction, checksums etc, so you can't ever achieve that speed.

In practise, bluetooth 1.1 will (again, from memory) struggle to get above 400kbps (equivalent) speed. This is fine when you're using it on your Z to surf the internet over a 512kbps adsl circuit, but not so good if you want to access samba shares!

Paul

Title: Bluetooth Speed
Post by: speculatrix on August 09, 2005, 05:28:17 pm

http://www.mobileinfo.com/Bluetooth/FAQ.htm (http://www.mobileinfo.com/Bluetooth/FAQ.htm)

Title: Bluetooth Speed
Post by: albertr on August 09, 2005, 08:36:32 pm

This falls down into two issues:
1. Hardware. Both UARTs (in BT module and in host computer) should support 921600 baud.
2. Software support. While module's firmware is not a problem, some linux kernels are so bloated that they might have problem with interrupt timings with 921600 baud.
That said, I can run CSR BC2 BT module @ 921600 baud on my Zaurus when hooked to OX950 UART.
-albertr

Title: Bluetooth Speed
Post by: dan on September 26, 2005, 07:28:10 pm

This seems to be more of a gui limit than anything real.   If you like you can go into the /home/root/Settings/NetworkSetupPPP.conf file and change the appropriate variable to 921600.

I havn't run any tests, but it seems faster.  Just make sure that you don't go into the gui configuration for that interface afterwards or it will knock you back down to the default speed (5700 or something) and that is definitly noticable.

-Dan