yeah thanks, but it didnt seem to have that command in the manual im lookin
at,
(v2.00) so I just wired cts high and ignored rts.

im not sure what the pc end does with flow hw control
as its via the bluetooth dongle, I cld play around with this
if it still gives trouble, but for now it seems to have solved this
last problem.

I think I just have it set so the hw flow control output lines are asserted
but the flow control inputs lines are ignored.

well, when it went wrong the rts line was de asserted,
and reading all the characters available at the pc didnt
clear the condition and didnt re assert rts,
anything I did at the pc end didnt clear it,
and it just stayed connected.

hmm maybe the confusion is im never clear wich direction rts/cts are going
in,
despite wiring up rs232 conections 100s of times,
we seem to be using oposite directions,
but going by the manual rts is an output from the modem,
I usualy just go by wether the manual says is input or output.

I think it messed it up when it got many more characters when rts was
inactive.
idealy it should just ignore any more chars,
and recover gracefully, but this doesnt seem to be the case.

the messages are short packets of 25chars avg csv (comma seperated
variables).

the remote device isnt realy capable of buffering much so the data logging
eqpmnt just simply has to keep up.
it does usually, seems to be when I stop the data loging aplication to debug
it
or some other windows thing suddenly decides to hog the cpu that it hangs
up.

I did have the appp as high priority but under some conditions it could hang
the pc,
particularly sometimes when it trties to open the com15 port and it doesnt
open straight away.
or maybe its garbage collection in my c# app hmmm ...

the odd missed data packet isnt too much trouble,
but when it hangs up for hours it is.

I had to add crc error detection becuase the microcontroller uart dma has an
intermitent problem where it repeats chars.
but otherwise the system has virtualy no errors

the system is rotating so needs wirless transmision,
but is right next to the pc,
although I wish id used a diferent method,
maybe more slip rings wich I use 2 for power already,
or irda.

what would be realy neat is if I could have a wirless usb conection,
then the usb microcontroller programer could remain on the moving platform.
there are wirless routers wich have usb ports,
but these only claim to support a limited set of printers etc.

anyway thanks again for you help and interest,
seems i might of solved it,
although ive had it apart for the last few days,
there are parts spinning at 10krpm and its
taking a lot of fiddling with to get it running smothly enough.

Colin =^.^=

Hi John,
Hi Colin,

thanks for your very interesting discussion.
My problem with bluetooth gps units is the following.
I use Nokia 770 to connect to a remote bluetooth ghps device to read
nmea sentences by a navigation application.
One option toi select provided by software is scanning for bluetooth
enabled devices.
So I select scan and get a list of bluetooth devices and their
respective mac addreses, than I select one and connect to my gps unit.
Unfortunately, sometimes fix or signal is lost and a software
reconnects.

So sometims I test few gps units and would like my application to
perform scanning, self-selection and
re-select another gps unit given its fix is on .
So to have a number of gps units on and have an application to switch
into discovering mode and select another unit if signal from the first
is lost or no fix is available.

As I see, bluetooth enabled device like gps can be considered a serial
modem and AT commands are valid.
There is a number of application , open-source under Linux to work
with BT gps devices.
But I still can't understand how they work in discovering mode,
discovering every BT gps unit in proximity, reading its mac address.
How scanning is done ?
Thanks for your kind explanations.

Darius