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Re: Pcmcia card speed



Hi,

> I can only talk from my experience with BlueZ and here everything
> works find when setting the serial port's rate to 115200 because the
> card itself will then deal with the rest, i.e. it really connects at
> 921600 because the UART chip inside the card is modified this way.

I have to disagree. Brainboxes' CF cards have a modified UART that runs
at either 38400 or 921600 baud (according to their documentation), but
their PCMCIA cards have a real 16950 UART and the CSR chip is preset to
run at 115200 baud. So, "out of the box" BBs PCMCIA cards run at 115200
baud.
To use other baud rates, both the CSR chip and the UART must be set to
other rates (in that order). It is possible to set the CSR chip's
baudrate either with BB's Windows tools or OpenBTs vendor specific
functions (the later doesn't work for me), but setting the UART to
921600 baud seems to be complicated, as it runs at 115200 baud when
setting the divisor register to 1. If you look at the serial kernel
driver (2.4.12), setting a baudrate higher than 460800 at a 16950 UART
has no effect, as the driver has no support for the 16950's CPR
register. The strange thing is that according to the 16950 specification
the CPR register should be disabled after a chip reset, so the baud rate
should be the maximum possible.
Unfortunatly, Brainboxes was so far unable to provide help in this
affair. I really doubt if anyone has ever got their PCMCIA cards working
with "real" 921600 baud under Linux. What data rates do you get with the
cards?

br, Ulrich Mueller