On Sun, May 02, 2010 at 20:56:36 +1000, Aaron Mason wrote: > On Sun, May 2, 2010 at 5:33 PM, Neil O'Brien <[email protected]> wrote: > > On Sat, May 01, 2010 at 15:30:28 -0700, J.C. Roberts wrote: > >> > status = tcsetattr(fd, TCSANOW, &options); > >> > >> How does it behave if you use "TCSAFLUSH" rather than "TCSANOW" ? > > > > I made that substitution and added a > > #define DEBUG 1 > > > > The resulting binary sometimes fails to return and I then have to > > hit ctrl-c. I've tried it several times, and not seen any (repeating) > > pattern in terms of when it works and when it fails. > > > Is the system running Linux running on the same type of board as your > OpenBSD system? If not, try running Linux on a system identical to > the one you're using - see if it's the board causing the problem. >
Hi Aaron, No, they are very different machines. I don't have a spare ALIX system that I can load Linux onto for testing. If I can't resolve it any other way I will switch my current machine to Linux; but having just got everything set up in OpenBSD, I'd like to avoid that if possible. I have however tried the code in my initial email on a different OpenBSD machine (a Dell Optiplex Pentium II, dmesg is at http://www.tigerturnings.dyndns.dk/dmesg-dell) In this case I used cua0, the onboard serial port, on an ns16550a controller. Running the example from my initial post, with #define DEBUG 1 added and /dev/ttyU0 replaced by /dev/cua00, I get sporadic failures: # time ./ex_obsd_now_cua0 ; sleep 3 ; time ./ex_obsd_now_cua0 Port has been opened and set up 1 bytes available, read: 6 0m0.12s real 0m0.00s user 0m0.00s system Port has been opened and set up ^C 0m7.00s real 0m0.00s user 0m0.00s system If I replace TCSANOW with TCSAFLUSH on this machine, it doesn't help, though the instrument does sometimes send 21 (NAK) which I've never seen it do when using TCSANOW. # time ./ex_obsd_flush_cua0 Port has been opened and set up 1 bytes available, read: 6 0m0.14s real 0m0.00s user 0m0.00s system # time ./ex_obsd_flush_cua0 Port has been opened and set up ^C 0m3.97s real 0m0.00s user 0m0.01s system # time ./ex_obsd_flush_cua0 Port has been opened and set up ^C 0m3.65s real 0m0.00s user 0m0.00s system # time ./ex_obsd_flush_cua0 Port has been opened and set up 1 bytes available, read: 21 Expecting <ACK>, got 21 0m0.23s real 0m0.00s user 0m0.00s system I think that this should rule out any problems with the USB-RS232 converter or its drivers, and with the USB controller on the ALIX system. I'd be grateful for any further ideas or suggestions. -- Neil
