On 2012-02-02, Chris Adams <[email protected]> wrote: > Once upon a time, unruh <[email protected]> said: >>In the latest linux kernels, the pps option is already included, if >>selected by your distribution. > > I'm using parallel port PPS with Fedora 16. I did the following:
As I mentioned, the problem is that parallel ports are becomeing rare on motherboards, and the parallel ports on add in cards are almost always ports with "shareable" interrupts, which means that they are level triggered not edge triggered. This means that they keep pouring out interrupts as long as the level is high, which means taht the system gets 10s of thousands of interrupts for each time the interrupt comes in from the GPS ( about 100ms long). At least this is what I found. The parallel port hardware does not seem to have anything which tells it to stop sending interrupts on a high ACK after the first one has been handled. > > - put this in /etc/sysconfig/modules/pps.modules (mode 755): > #!/bin/sh > exec /sbin/modprobe pps_parport > /dev/null 2>&1 || : > > - put this in /etc/udev/rules.d/99-local.rules > SUBSYSTEM=="pps", MODE:="0640", GROUP:="ntp" > > - put this in /etc/ntp.conf > server 127.127.22.0 minpoll 4 maxpoll 4 > > Serial port PPS would need to load pps-ldisc instead of pps_parport (who > knows why one has an "-" and the other an "_") and an extra step to call > ldattach to attach the PPS line discipline to the appropriate serial > port (not sure where the best place to put that would be, maybe after > loading the module?). > _______________________________________________ questions mailing list [email protected] http://lists.ntp.org/listinfo/questions
