[Gumstix-users] Re: BT on BTUART

[Henk M. <he...@co...>]

On Feb 28, 2005, C Hughes wrote:
> On Feb 28, 2005, at 12:52 AM, Tim Auton wrote:
>
> > There may not be any more hardware serial ports, but there are plenty 
> > of GPIOs. With the oomph of the PXA255 I wouldn"t have thought 
> > bit-banging serial using the GPIOs would be a prohibitive overhead. 
> > I"m confident that the hardware is up to the task, but I"m no Linux 
> > kernel hacker, so there may be a world of stuff I"m missing there.
>
> I think as has been pointed out that bit-banging a new "UART" on GPIOs 
> would be difficult if not impossible in practice at any reasonable baud 
> rate.  However, creating a "super serial" buddy board with 2, 4, 8, 
> however many UARTs you want, linked to the PXA over SPI would work 
> fine, and likely be pretty easy to implement,
>

Hi Craig and others,

This only works for folks who have not yet integrated the Gumstixes in
their system. I am the proud owner of twenty custom-made boards that
interface the gumstix to our sensor/power bus. Yes, you guessed right, the
sensor bus runs of the HWUART. (We developed this board based on a Gumstix
with a working Bluetooth interface on the BTUART, I think it was r35 of the
software.)

The problem is that neither the interface boards nor the Gumstixes are big
enough to function as door-stops...

Given that the Bluetooth module is soft programmed, it appears to me that
the solution may lie in Infineon releasing a version of their firmware that
properly interfaces with the BTUART interface of the PXA255. This does not
seem to be a Gumstix specific problem, and as such, Infineon has an
interest here. Am I right in all those assumptions? If so, has anyone from
Gumstix tried and lean on Infineon?

In the meantime, I suggest that the kernel module that initialises
gpio4[2345] gets a parameter which tells it which UART to go for. Ie,
usebtuart=1 will cause it to use the BTUART. That way, people who need the
HWUART do not have to patch the kernel, but can just patch the root file
system.

Any help greatly appreciated.

H-)

University of Bristol, MV Building, Woodland Road, Bristol, BS8 1UB, UK.
+441179545137    http://www.cs.bris.ac.uk/~henkm/    he...@cs...