David Lord <[email protected]> wrote: > Rob wrote: >> I would like to use the Atom driver (22) on a Linux system with a >> parallel port. It is not clear to me from the scattered info I have >> found on internet if this is going to work. >> >> Using a modern Linux kernel with the PPS module, is it possible to >> symlink /dev/pps0 to a parallel port device and then connect the PPS >> signal to the ACK input (pin 10)? >> >> If not, what else is required to get this working? >> >> Examples always refer to the use of a serial port DCD input, but for >> best accuracy (in the microsecond range) I think the parallel port >> is better. >> (no RS232 drivers/receivers, no funny UART that may delay interrupts) >> >> Any other suggestions for an accurate PPS input? > > On NetBSD with stock ntpd, pre 2010, I did comparisons of > pps from Sure GPS with output from dcd at ttl level vs the > "serial" dcd but didn't really see any consistent difference.
Did you try the parallel port? I am interested not only in jitter but also in any constant offset between the PPS pulses and system time on different systems (possibly using different makes of serial card). 4-6 us would be good enough for my purpose, but it would not be good when one system had a 10us offset because of a propagation delay in a linedriver/receiver. _______________________________________________ questions mailing list [email protected] http://lists.ntp.org/listinfo/questions
