Chris Albertson <albertson.chris@...> writes: > > On Fri, Apr 6, 2012 at 9:41 PM, Andrew Rodland <andrew@...> wrote: > > > Another option would be building something on an FPGA. This would be a > > considerable stretch for me, since I've never done FPGA work, but if I build > > from the ground up, I can have *very* tight control over things that are chosen > > for me with a micro controller. > > A compromise is to find a "soft core" for the FPGA. This is a CPU > implemented in FPGA and then it runs software just like a "real" CPU. > This would let you move your micro controller based be sign over to > the FPGA quickly. After that you can implement some specialized > peripherals that do time stamping > > How does the performance of the Arduino based NTP compare with what > you could do with Linux on (say) and Atom or ARM processor?
Pretty well, I think. A PPS generated by my board shows an RMS absolute jitter of 174ns compared to a Spectracom 9183, which is almost impossibly good considering that all the timing is done off of a 2MHz clock. As measured from the NTP side, the performance is diluted a lot by the fact that the W5100 ethernet chip has unknown and unpredictable delays, but it still comes back with a jitter of <20us (possibly better — the box I'm using to measure the NTP is a Linux machine that isn't really a timing champ. Wish I still had my net4801.) Andrew _______________________________________________ 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.
