[time-nuts] How to get PPS from ublox mini-PCI GPS to APU2 SoC serial port for ntpd

STR . strykar at hotmail.com
Sun Aug 14 12:37:21 EDT 2016

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-bounces at 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 at 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 ." <strykar at 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.
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