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mikalhart / TinyGPSPlus

A new, customizable Arduino NMEA parsing library
http://arduiniana.org
1.1k stars 494 forks source link

Do not use date/time until we have a fix. #6

Closed denravonska closed 7 years ago

denravonska commented 10 years ago

It turned out that some (?) receivers use an old timestamp in at least GGA when they do not have a position. This causes the date/time to become unreliable so it's better to wait until we have some sort of reception.

This invalidates #2 and closes #5.

stilldavid commented 8 years ago

I'm not the repo owner, but I'm going to point out that some receivers (like the Adafruit Ultimate GPS) have a built-in RTC with a battery backup. I'm using one as a time source, and it's nice to be able to pull the time without requiring a location fix. In this case, the time will still be valid even without a position fix, which I consider a feature and not a bug.

AlyssonRowan commented 8 years ago

While my GPS continues to produce valid timestamps,it does not include a date.

I agree that this is definitely a feature, but the RTC in my (inexpensive) GPS does tend to drift rather more than the DS3231 RTC that I have installed on my arduino.

I am currently working on a navigational app whereby the built in RTC is updated occasionally (top of the hour - ish) when there is a fix from the GPS, and the display time is fed from the RTC rather than the GPS.

On 14 February 2016 at 17:32, David Stillman notifications@github.com wrote:

I'm not the repo owner, but I'm going to point out that some receivers (like the Adafruit Ultimate GPS) have a built-in RTC with a battery backup. I'm using one as a time source, and it's nice to be able to pull the time without requiring a location fix. In this case, the time will still be valid even without a position fix, which I consider a feature and not a bug.

— Reply to this email directly or view it on GitHub https://github.com/mikalhart/TinyGPSPlus/pull/6#issuecomment-183933785.

mikalhart commented 7 years ago

I think the comments from @stilldavid and @AlyssonRowan have convinced me to leave this as is for now.