OK, I've hooked the Ublox6 up to a Debian box and I guess I've been wrong when I've described the interface as a USB-UART. In fact, its using the cdc_acm driver, the "Abstract Control Model driver for USB modems and ISDN adapters", although the device /dev/ttyACM0 is showing up as a character device. I'm thinking I should have realised something was up when I had to link /dev/gps0 to /dev/ttyACM0 before, as opposed to /dev/ttyUSBx, but no alarm bells rang at the time.
I wonder where that leaves me, w.r.t to using the Ublox6 with ntpd on Win XP. I suppose I should continue to look at the generic NMEA device issues I'm having for now. Cheers, Darren On 27 Sep 2011, at 18:08, Long, Darren wrote: >> -----Original Message----- >> From: Dave Hart [mailto:[email protected]] > >> The GetFileType documentation points out that a return value of >> FILE_TYPE_UNKNOWN (== 0) means either the function failed, or the type >> of the handle is unknown, and one must call GetLastError() to know >> which. I suggest you debug the problem again and determine what >> GetLastError() is returning in this path. My guess is it's returning >> 0 (no error) indicating the driver handling the USB-connected UART is >> failing to set the right bits to indicate it's a communications device >> during the open operation. > > I can't step into GetLastError() itself, but 0 is being passed into > _dosmaperr(). > >> If GetLastError() is returning an error >> value, something else is going wrong. I'd really like to know whether >> GetFileType() is reporting an error or a legitimate FILE_TYPE_UNKNOWN. >> >> Assuming a driver problem, I understand there are relatively few >> USB-to-UART bridging chips in the market, with something called the >> pl2003 (IIRC) found in most USB-connected GPS pucks. With enough >> spelunking, perhaps you can arrange to use a better Windows driver >> compatible with your USB-UART hardware to work around this problem. >> >> I do question my guess, though, as I'd expect failure to report >> FILE_TYPE_CHAR would also prevent other terminal apps from using the >> device, as for example setting the serial port rate and configuration >> presumably fails on devices that do not present as a communications >> device. > > Hmm, well, it gets stranger and stranger. I've just tried connecting to the > Ublox6 again with putty and some in-house code that is specifically intended > to work with the USB attached Ublox6, at the wrong baud rate (should be > 9600, I've tried 19200 and 4800), with wrong number of start and stop bits > and different parity variations and everything still works, contrary to > expectations. I'm now even more confused. I'll take the Ublox6 home again, > and hook it up to a Linux box and see what I can learn about the driver it's > using. > > Cheers, > > Darren > _______________________________________________ > questions mailing list > [email protected] > http://lists.ntp.org/listinfo/questions _______________________________________________ questions mailing list [email protected] http://lists.ntp.org/listinfo/questions
