The picPET is vastly different from an Arduino. My goal with the picPET was to make a self-contained, single-chip, works-out-of-the-box continuous time-stamping event counter with an $1 8-pin DIP chip, even if the resolution wasn't good by time nut standards. You can see how simple it is: http://leapsecond.com/pic/
It turned out really well and is useful for many sub-microsecond timing projects. I do not use it to compare high-end GPS, rubidium, or cesium clocks. That's a different class of measurement. Note most microcontroller based time interval counters or frequency counters are not suited for high-accuracy or long-term measurement because they lose cycles with sloppy hardware or poor software design and depend on cheap crystal oscillators. /tvb ----- Original Message ----- From: "Anders Wallin" <[email protected]> To: "Discussion of precise time and frequency measurement" <[email protected]> Sent: Thursday, January 23, 2014 3:31 AM Subject: Re: [time-nuts] PICPET- was Affordable (cheap) COTS (etc) > Given that Arduinos are now sold in (almost) every super-market, and the > programming IDE is free/open-source, and the C/C++ code is familiar to > many, I would have thought the logical evolution of the "pictic" is to > become an Arduino shield? > > One drawback (AFAIK) is that e.g. Arduino Due doesn't have a dedicated > counter/encoder input, like the dsPICs made for motor-control have. > On the other hand the Due has 12-bit analog inputs (and DACs) that might > work for interpolation. > > How fast can the QEI (quadrature encoder interface) on a dsPIC clocked at > 140MHz count? Were you planning on using a dsPIC with two QEIs, for TIC > start&stop coarse counting? > For 1ns or 2ns resolution an analog (or fpga?) interpolator is required > anyway? > > AW > > > On Thu, Jan 23, 2014 at 4:10 AM, Tom Van Baak (lab) > <[email protected]>wrote: > >> Hi Bob, >> >> It's pretty easy to get a tiny PIC or AVR down to 50 ns, so to me the next >> sweet spot would be 1 or 2 ns. A couple of us are trying. Contact me >> off-list re the dsPIC33. >> >> /tvb (i5s) >> >> > On Jan 22, 2014, at 5:53 PM, Bob Stewart <[email protected]> wrote: >> > >> > Tom, >> > >> > Do you know of any other PIC projects that get a greater resolution? I >> was thinking of doing something with a dsPIC33 running at 140MHz or >> greater, but I'm not sure I want to devote the time to if it's it's been >> done. >> > >> > Bob >> > >> > >> > >> > >> >> ________________________________ >> >> From: Tom Van Baak (lab) <[email protected]> >> >> To: Robert Atkinson <[email protected]>; Discussion of precise >> time and frequency measurement <[email protected]> >> >> Sent: Wednesday, January 22, 2014 7:39 PM >> >> Subject: Re: [time-nuts] Affordable (cheap) COTS / eBay kit for TIE / >> 1PPS phase comparison >> >> >> >> >> >> As much as I'm fond of my picPET it has 400 ns resolution and not >> intended to replace a 5 or 10 or 50 ns TIC (which is what the OP asked for). >> >> >> >> /tvb (i5s) >> > _______________________________________________ >> > time-nuts mailing list -- [email protected] >> > To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> > and follow the instructions there. >> _______________________________________________ >> time-nuts mailing list -- [email protected] >> To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. >> > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
