[email protected] said: > My specific question concerns the case that one of the boxes is a computer, > for example, a Linux box with time kept using ntpd or chrony (perhaps also > listening to a PPS signal coming in on a serial port). But I've never seen a > computer with a PPS *output*.
There is code in the Linux kernel to generate a PPS output. I've never tried it. I think it uses the printer port which isn't available on modern systems. You can probably get a PCI plugin card. You will probably have to build your own kernel. If I wanted to try something, I would write a user-level hack to flap a modem line and compare that to a PPS signal. The code would look something like this: t1 = time() set line low t2 = time() set line high t3 = time() log t2 and t3 wait 1/2 second set line low wait 1/2 second loop The first time/set is to warm out the cache. > (Perhaps PPS is overkill for this situation; perhaps it's the case that given > the inherent inaccuracies of software-based timekeeping, a software-based > query mechanism -- perhaps using ordinary NTP or PTP protocols -- would be > sufficient for That just gets time from one computer to another. Now you have the same "is it right?" question on another box. -- These are my opinions. I hate spam. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
