GPS library
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GPS library

by Occitan on Mon Dec 04, 2017 12:36 pm


I am using the Adafruit ultimate logger shield.

With the documentation provided I succeed in making all the steps of GPS data acquisition and SD logging and I hope that will be enough for my own project (autonomous GPS guided platform). With the help of forums on internet, I also succeed in replacing the UNO by a MEGA in order to have more memory.

However, I would have found nice to have a more synthetic description of the GPS library, for example like the description of the other usual libraries (Servo, SD, etc…).
I would also have appreciated some schemes explaining the GPS data stream and the different methods to cope with it (limitations when working in the main loop, timer interruptions, hardware interruptions, etc…)

Due the the lack of global understanding, some things are « mysterious »… For example I did not understand the line « uint32_t timer = millis(); » in the sketch….

Note however that I am nearly beginner in ARDUINO…. Perhaps all these things can be found in the cloud ?

Thank you in advance for your suggestions.


Posts: 4
Joined: Mon Dec 04, 2017 8:06 am

Re: GPS library

by adafruit_support_carter on Tue Dec 05, 2017 3:43 pm

Some of the fields obtained from parsing the data are explained here:
https://learn.adafruit.com/adafruit-ult ... ata-output
but understanding the underlying code fully requires knowing a bit more about Arduino and the C++ programming language. For example, the line you're asking about:
Code: Select all | TOGGLE FULL SIZE
uint32_t timer = millis();

isn't really specific to the GPS. This simply creates a variable named timer and assigns it the value returned by the Arduino library function millis(), which is documented here:
https://www.arduino.cc/reference/en/lan ... me/millis/

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Joined: Tue Nov 29, 2016 2:45 pm

Re: GPS library

by Occitan on Tue Dec 05, 2017 7:37 pm

Thank You for the answer.

OK for uint32_t timer. I have just found the explanation in the meantime in a forum...

For the rest of my questions, I understand I have to do my own experiments with interruptions and the GPS shield.
This should improve my understanding and this is in the spirit of makers around arduino...
Fortunately, this is not so critical for my project since my guided platforms goes slowly.

Thank you again.

Posts: 4
Joined: Mon Dec 04, 2017 8:06 am

Please be positive and constructive with your questions and comments.