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So, I thought I might try to set a time server (as one does). I have a nano ITX mb with a mPCIe slot on it, and I found a GPS card that supposedly outputs a 'timepulse'. It was cheap enough that I thought I could give it a try. After a bit of fiddling with gpsd I get a 3D fix, but no PPS data. So, shouldn't this give me a time pulse..? I sent an email to the manufacturer; I get a schematic back, apparently the timepulse is hooked up to pin 42 in the mPCIe connector. Now I don't know what to do. Is there any way to get the PPS signal from pin 42 in the mPCIe connector and into ntpd? Doesn't seem like any PPS kernel modules supports this natively, and PPS-tools is no help either.

Any assistance appreciated.

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  • \$\begingroup\$ UBLOX NEO-M8U datasheet suggests that timepulse output is disabled by default, and must be explicitly requested with "TIMEPULSE2" message. On pin 3 (digital I/O) of UBLOX module. This pin has other functions. \$\endgroup\$ – glen_geek Mar 23 '17 at 19:41
  • \$\begingroup\$ I see that, I could work with that, probably. I'm a little disappointed that they say "the module outputs a timepulse", when what they mean is; "if your motherboard has a LED, we can blink it". \$\endgroup\$ – torstefi Mar 23 '17 at 21:04
  • \$\begingroup\$ @torstefi It's quite possible that the module was intended to be integrated into a custom hardware design, where you could route that I/O wherever you wanted. \$\endgroup\$ – duskwuff Mar 23 '17 at 21:05
  • \$\begingroup\$ Yeah, probably, plus if I had a LED, it would blink on 3D fix; I can see the use case for that. I found a different mPCIe module, LS2603X-2RE from LOCOSYS, for which the datasheet promises "Support 1PPS synchronize with NMEA output " (In addition, it looks like, to outputting the timepulse on pin 49). Can't find it for end user sale anywhere, and the manufacturer went quiet when they understood that I'm not a business wanting to order hundreds or thousands of these cards. \$\endgroup\$ – torstefi Mar 24 '17 at 10:22
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Unlikely to be possible without custom hardware.

Pin 42 in the mini-PCIe connector is defined as "LED_WWAN#" -- it's an activity LED for cellular modems. It's unlikely to be connected to anything on your motherboard; even if it is hooked up, it's probably to an LED, not to any hardware that can be read by the CPU.

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  • \$\begingroup\$ Yeah, it's not hooked up to a led, so probably NC, then. The only idea I have left is to solder a wire to that pin and connect it to one of the board's GPIO pins. \$\endgroup\$ – torstefi Mar 23 '17 at 21:00

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