> 1. Does anyone know of a device that will take a 1PPS GPS timing signal and > generate a 32.768 kHz sine wave output ? I have big digital clock that uses > an 8 bit micro processor and an external 32.768 crystal. Obviously the > external crystal is awful for accuracy.
I don't know of any off-the-shelf device that does that. Have you looked at the micro? Is there a spare input pin for the PPS? Could you rewrite the software to use the PPS rather than counting to 32K? If you get a GPSDO with a 10 MHz output, then you could do it in software. I'm a bit surprised that tvb doesn't already have one as an option for his picDEVs. http://www.leapsecond.com/pic/picdiv.htm If you think (analog) hardware is more fun than software, you could build a PLL. I'm not a PLL wizard. My guess is that 32K:1 is too big a step. I'd probably try 2 steps of 256:1 and 128:1. If you like software, you can do the PLL in software. (Less hardware than the analog version.) The idea is to run a tiny CPU at some handy frequency, measure that clock using the PPS, and figure out how many cycles you need for each half cycle at 32K Hz. You don't need each (half) cycle to be super accurate, but the long term has to be right. If you knew the clock frequency and it was stable, the cycles-per-tick would turn into the same sort of math at Bresenham's algorithm gets for drawing diagonal lines: some steps are N cycles, some are N+1. I'll bet the code is nice and clean after you figure out how to do it. Maybe it's just a PLL in software. -- These are my opinions. 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.