[EE] Problem with virtual com port for bluetooth unit

Hi,

I have a problem with a bluetooth connecton for a GPS receiver, using a virtual 
COM port in a PC.

My setup is as follows:
LevelOne usb bluetooth adapter (have also tried adapter from MSI).
Globalsat BT338, bluetooth GPS receiver.
Standard windows bluetooth stack in XP, sp2 (have also tried Toshiba and Blue 
Soleil).
A virtual COM port provided by the BT stack (bthmodem.sys).

My problem is that as soon as I open the virtual com port for the GPS receiver 
in my program I get 100% CPU usage (even when there is no communication). The 
component I use to communicate with serial ports is an ActiveX component called 
Commx from Greenleaf and my program is written in unmanaged C++ with visual 
studio 6.

The problem seems to be that the commx component doesn't like the virtual com 
port. Hyperterminal and other terminal programs seems to work fine. When I 
study the problems more closely it actually seems that it is one of the three 
threads created by commx when a port is open that loads the CPU. I can also see 
the trace message "Bad result from GetOverlappedResult in status thread" 
continouously in the trace window when I run the program through the debugger. 
The status thread is the one that handles pin change on the status and 
handshaking pins I think. All this seems to indicate that it actually is CommX 
that is the problem here. Other virtual comports seems to work fine though (USB 
to serial converter for example). I have been in contact with Greenleaf about 
this but they are clueless.

So my question is this: Could it be anything else but the commx that is the 
problem? Perhaps the virtual com port for the bluetooth device is working a bit 
differently? Have anyone seen this problem before and have found a solution for 
it? 

/Ruben
==============================
Ruben Jönsson
AB Liros Electronic
Box 9124, 200 39 Malmö, Sweden
TEL INT +46 40142078
FAX INT +46 40947388
ruben <at> pp.sbbs.se
==============================
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