2019-10-22

GPS made easy

I am surprised how simple GPS is these days. For only £12 or so (from RS of all places, part 908-4085) I can get a small module with built in antenna that runs of 3.3V and provides serial GPS data and a very precise PPS output, is only 15mm square, and easily soldered to a PCB. It even has built in RTC that can run off a small button cell battery for fast fix and retaining time of day.

I have yet to decide on the best applications of this, apart from simple things like a speedo for a bicycle. There are applications with location logging (that dump to WiFi when back in range), or even if you just need a reliable time source for something like a door entry system (or a Brexit countdown clock, LOL).

A clock showing how long until sunset, wherever you are, would be cool :-)

I have made a module with GPS (the Adafruit module, as I found that before the RS part), and a display, so I can have a play around with it.

P.S. I have it set up for my bike, even with amount of daylight left...


5 comments:

  1. I was wondering how easy would that be for you to use it as NTP source?

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    Replies
    1. The module, obviously, especially with the high accuracy PPS. Obviously not so much if you use an ESP32 on Wi-Fi with it :-)

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  2. It lacks a PPS input but I use a GPS as a time source on Mikrotik routers which operate as local NTP servers.

    Maybe you could do the same with firebricks but add in the ability to accept PPS for extreme accuracy.

    Mikrotik have just started playing with IEEE 1588 on one of their switches so maybe they'll add GPS PPS support in the future as well

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    1. Without PPS you are liable to get skews that are greater than those caused by using remote network NTP servers.

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    2. Thanks Chris,
      Not too worried about small skew issues currently. Mainly happy with the convenience of the Router getting date/time and NTP setup early after boot, even without Internet access. In the future I might look at utilising something like a Pi with a GPS hat and PPS input to operate as a Time Source/NTP Server if I need greater precision.

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