Parameter restore procedure when replacing a flight controller

Due to real (or suspected) flight controller damage or defect its helpful to have a clear understanding of the recommended procedure to load & update saved parameters from an old unit to its replacement.

Since many of the saved parameters are calibration data unique to the original device (e.g. accelerometer, compass related params), loading the parameter file from the old unit, also loads that old calibration data (I assume).

Is the recommended procedure to load the param file saved from the original device and then “re-calibrate” using the “initial configuration” tools in Mission Controller ?


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We normally don’t recommend reloading all the parameter values from a file because there isn’t actually enough room in the eeprom to hold individual values for each parameter so there is a risk of filling up the eeprom which would lead to being unable to update parameters. Still, I’ve almost never heard of this happening.

For me, I normally do a compare using MP’s full parameter tree screen and then just load the more critical parameter values like the tuning values that mostly start with ATC_ and FS_ and SERVO_

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You should (or may) re-load the parameters several times from file and re-boot the flight controller in-between. Some parameters like Q_ENABLE will not allow further Q settings from file until you re-boot and load them a second time once the feature has been enabled. This is evident when many of the parameters fail to write to the FC on the first attempt. I’m not sure about Rover.

Good luck!

Thank you very much Randy & Greg for your responses, though I’m still far from clear on this.

Greg seems to be saying there is sufficient room in persistent storage for all parameters to be loaded from a saved file, while Randy seems not so sure that’s true. How could the eeprom not be big enough to store all the parameter values ? Where else would they be stored ? Manually setting parameters from a “tree compare” seems pretty error prone & tedious - especially for systems with a large number of special devices and characteristics.

The “Q_” parameters appear to be relevant only for Quad-motor planes. Greg seems to imply there may be other similar parameters that require enabling, rebooting & reloading in order to be fully transferred ? Is there a list of these or a way to identify them ?

Finally, assuming one can ultimately load all parameters from a file, does the calibration data also get loaded, and can it be reliably updated by re-running the MP “initial setup” calibration tools on the replacement/ cloned flight controller without adversely affecting the other parameters ?

Its surprising a recommended procedure for flight controller replacement and/or “cloning” does not seem to exist since it is such a common need - e.g. how do suppliers of turn-key drones handle this ? If a written procedure does not exist and I can collect answers to the questions above, I would be happy to draft one for inclusion in the wiki(s).

Hi Tom,

Randy is the expert here. I’m more in the “do this because I’m lazy and it should work” department. In my experience, restoring params from file in either Copter or Plane seems to work fine. You can tell if you need a reboot after a certain parameter if other associated params fail to write. It’s a technique they use to reduce the size of the parameter list for unused features.


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I would at least recommend skipping parameters that start with:

RC (except RCx_OPTION)

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I think you should try out the “compare” feature, which lets you load only the params you choose, and just de-select the ones you don’t want. The calibration numbers are in there for you to choose to load or not as well.

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