Precise Timing options

Tachyon
1

Hello,

I was wondering if the GNSS receiver on the Tachyon allows to route a 1 PPS signal or similar to one of the header pins? For my application I need a sub microsecond timing accurate synchronization signal and was hoping I could use the inbuilt GNSS receiver for that, otherwise I may have to add an additional GNSS module, which I’d like to avoid.

Thanks a lot!

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Thanks for asking, @niklasc!

The QCM6490 on the Tachyon supports GNSS (GPS, GLONASS, etc.), but it doesn’t provide a PPS (pulse-per-second) output directly. That functionality typically comes from a separate GNSS module, so if you’re looking to use PPS for time sync (like with NTP or Chrony), you’ll need to connect a GNSS module that exposes a PPS signal on a GPIO.

We do synchronize time from cellular networks, but also don’t have a precise ms accurate time stamp sadly.

Since you’re using Tachyon, which is Raspberry Pi compatible, you can easily add one of the Raspberry Pi HATs that provide PPS:

1. Adafruit Ultimate GPS HAT

  • Based on a u-blox GPS chip

  • PPS on GPIO 4 by default

  • Works with gpsd and ntp or Chrony

  • Well-documented and reliable - we use their modules in our own products!

2. Waveshare MAX-M8Q GNSS HAT

  • Also uses a u-blox chip

  • Exposes PPS via a header

  • Compatible with standard Linux PPS tools

Both are low-cost and known to work well with Pi-style boards like Tachyon.

Hope that helps!

Thanks

Nick

1 Like
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This blog describes the implementation of an NTP server on a Raspberry Pi. What is needed for NTP is precise timing. The author is using a Uputronics GPS hat.

Raspberry Pi NTP Server - Part 1

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