There should be no difference between COM2 or COM3/4, all four UARTs are likely hard logic. GPIO is just an alternate function for the COM3/4 pins. It will come down to what your are more comfortable with code or soldering. The NCT5104D is a QFP and its pins are reasonably accessible using 30 AWG or finer gauge wire.
On Sun, Aug 14, 2016 at 12:37 PM, STR . <stry...@hotmail.com> wrote: > Thanks for your previous email, it shed light on the situation of choosing > COM ports. > > COM1 is required for console access so that's out. > COM2 has headers and seemed like an obvious choice as I have no real need > for a 2nd serial port. > > I wish to power the GPS via the mini-PCI slot to avoid soldering power > cables along with a PPS line. > Will there be any difference in jitter between using the COM2 header or > COM3 provided by the NCT5104D GPIO pins? > Or will they both be identical in performance? > > > -----Original Message----- > From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Attila > Kinali > Sent: Sunday, August 14, 2016 5:30 PM > To: Discussion of precise time and frequency measurement < > time-nuts@febo.com> > Subject: Re: [time-nuts] How to get PPS from ublox mini-PCI GPS to APU2 > SoC serial port for ntpd > > On Sun, 14 Aug 2016 08:29:48 +0000 > "STR ." <stry...@hotmail.com> wrote: > > > Serial port 3 and 4 are provided via the GPIO pins connected to an > NCT5104D I/O controller which is 5V tolerant. > > http://datasheet.octopart.com/NCT5104D-Nuvoton-datasheet-38893851.pdf > > I believe that's why it was suggested to avoid the 3V-5V conversion. > > Oops.. I missed that the other UARTs were connected to the GPIO header. > > If you use those, you can directly connect the LEA outputs, as the LEA > does use 3.3V CMOS for I/O. > > Attila Kinali > -- > Malek's Law: > Any simple idea will be worded in the most complicated way. > _______________________________________________ > 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. > _______________________________________________ > 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. > _______________________________________________ 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.