> The temperature swings won't be large, just the usual diuneral indoor cycles.
In California, the diurnal temperature swings are big enough to be useful. :) This is what ntp sees the main/CPU crystal doing in a non airconditioned room. Each color is a different day. http://www.megapathdsl.net/~hmurray/ntp/slope.gif The swing would be much bigger outside, especially with an open sky. > Since we'd be measuring 4 PPS signals that won't be in phase, I wasn't > planning on sleeping for long. But, I some 10 usec sleeps with usleep(10000) > after reading a pulse would be reasonable. But, with the system not doing > anything but polling and writing to the disk, I wasn't expecting much > interruptions from other processes. I was thinking of keeping track of when you expected each pulse to arrive next and sleeping until a little before you expected the soonest one. (Adjust "a little" by trial and error.) I agree that Tom's picPET will be a fine way to do it. I was just playing with how to do it with the parallel port. It's still an interesting question of how accurate you need to measure the time. That's probably a good one to work through with your son on the back of an envelope. How are you measuring temperature? -- These are my opinions, not necessarily my employer's. I hate spam. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
