NEO-M8U : Is it possible to retain sensor calibration using UPD-SOS messages ?

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NEO-M8U sensors are recalibrated every time it is powered up and the vehicle is expected to make certain calibration movements. This means the vehicle will spend some time before starting to get sensor measurements.

We would like to fix calibration data once and for all after we install the module in the vehicle.

From what i understand from the datasheet, we can use V_BCKP for this but 15uA typical consumption is too much for our application. It is a huge drain in our battery which is expected to last for 20 years or so.

But we have some other advantage; we know main power is off and the module is alive for at least 10 more seconds. We want to know if it is possible to save sensor calibration data into NEO-M8U flash during this period. 

Our question in summary :

Can we use "UPD-SOS Create Backup File in Flash" command  to retain sensor calibration settings ?  If we save BBR memory right before power-down, could the module wake up with calibrated sensors ?







by makiferol asked Nov 7, 2018
0 votes
Yes, you can use UPD-SOS command to save calibration data. Search this forum for UPD-SOS and you will find answers and references.
But you must verify how much time that command takes to complete.  Do some lab tests to confirm that is UPD-SOS storage is complete within the sustained VCC duration.
Note that while calibration is saved, after two-to-four hours ephemeris data is stale hence your TTFF will be in the 18 to 36 second range with good signals.
by grampy answered Nov 7, 2018
by makiferol selected Nov 8, 2018
Best answer
Hi Grampy, thanks for the answer.

We don't mind TTFF requiring hot start after several hours. We just want to make sure that when vehicle is powered up, it can wake up with pre-calibrated fusion sensors and provide roll-pitch-heading values along with dead reckoning before GNSS. I assume this is possible then ?

We have relative protocol specification document. We will try this feature but i wanted to be sure if it is technically possible.

Clive :  I forwarded my two questions with "project form" as well. I plan to your visit your booth in Electronica for some questions too.
0 votes
This is a user forum, for technical questions related to specific functional implementation details you should discuss with the FAE assigned to your account/project.

You could also just test your hypothesis and come to some conclusions. Certainly to the point where you could ascertain whether something is or is not happening.
by clive1 answered Nov 7, 2018
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