Navio2 GPS solution rate issues

Hi everybody,

I am running a modified version of GPS.py from the Emlid’s Github example repository and I want to store data from GPS and IMU at 5 Hz.

While I am receiving data from the Navio2 GPS, if I store and substract 2 consecutive iTow fields, the elapsed time is not constant. Moreover, it is generally 400 ms, in spite that in the code I set the GPS solution rate to 200 ms.

Yesterday I found out that lowering the SPI baud rate from 5000000 to 200000 improves the situation (at 5000000 I got GPS readings at about 1Hz and sometimes even lower).

The Python code is available in https://gist.github.com/gmsanchez/1145c42ae6a20d2867bec42cadc2e636

and the modified ublox.py file in order to support PVT messages can be found in the following fork https://github.com/gmsanchez/Navio2

Thanks in advance!

I am experiencing the same situation. What is more strange, even though the elapsed time is not constant, it’s always a multiple of the configured frequency. I.e., if I set the rate to 5 Hz, sometimes I get 200ms, and sometimes 400ms or 600ms, but never something like 260ms. And the fact that lowering the baud rate from 5000000 to 200000 improves the situation is also very strange. Does anyone have any idea about what could be causing this behavior?

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