Missionplanner can't calibrate accel on MINI APM 3.1

My quad is suffering from vibrations. :cry:
First of all let me explain, that I did everything in my power to eliminate these vibs.
I balanced the props, motors (also dynamically the best I was able to). Also put the Mini APM 3.1 on several vibration dampening pads (Orange foam from HK, Dampener with 4 rubber balls, Moon gel and so on. Also used super soft silicon cables to enter the Mini APM)
All came out with no satisfactory result for me. :cry:
So here is what I want to ask:
I want to downgrade the Mini APM 3.1 to a former firmware, let’s say 2.9.1 so the sensitivity is not that much of an issue anymore (I hope)
BUT…. After downgrading, I can’t perform an accel calibration. :open_mouth:
Missionplanner “walks” through this section so fast that I can’t even touch my keyboard fast enough. :astonished:

So my key question is: Has anyone experienced this also? And how can I downgrade in a proper way so Missionplanner will accept my input?

Try APM planner2

Never tried this planner before, now there’s another issue for me. :confused:
How do I install an older firmware like 2.9.1 ?
The planner gives me only the latest one possible for the mini APM 3.1 (V3.2.1) :astonished:
In Missionplanner I can choose the older 2.9.1 version, but that gives me the calibration issue.

EDIT:
Tried flashing V2.9.1 with MissionPlanner and after this I wanted to calibrate the accel with APMPlanner2.
Another thing occured. Calibration doesn’t do anything but waiting for the timeout of 40 secs. :frowning:

APMPlanner2 does not have support for flashing older firmware(yet).
you can still download/compile any/older firmware and flash it as “custom” firmware.

I start to suspect 2.9.1 had an old calibration process.
BTW: why do you prefer that old firmware ?

Thank you very much (again) Andre. :smiley:
I just want to try an older version, because the older versions seem to be less sensitive to vibrations. At least so i read on the net.
I’m gonna try your suggestion "you can still download/compile any/older firmware and flash it as “custom” firmware."
I will let you know when I get back from my holidays, because I’m leaving tomorrow for 2 weeks and i won’t be able to do anything on my quad. :frowning:

I would suggest to reduce vibrations or improve damping try different foam, and make sure cables are not too tight, or loose, conducting vibrations.

Otherwise you may have bent motor shafts or very poorly balanced propellers.

the advantages EKF improvements make to reliability, and other improvements since 2.9 time would not make me even consider going back. I’d say current ArduCopter on a Pixhawk , is easily the most reliable/professional AP for a multirotor these days.

I know “something” about vibration dampening and balancing motor/props :wink:
My DIY Hexacopter with a Pixhawk flashed with AC V3.2.1. is standing like a rock in the sky. :smiley: :smiley:
But my Walkera QR-x350 PRO with the MINI APM 3.1 is suffering vibs like -3 to -25 on the Z-axis. :smiling_imp:
Perhaps you’re right on one or more bent axis, so I’m gonna check this when I get back home.
Do you know if EKF is also possible on the MINI APM 3.1 :question:
Does it have anough calculating power (only 8 bit) :question:

no, APM* and APM clones do not have the processing power, nor the program space to run EKF.