Possibly faulty barometer component in APM 2.5

Is there any way I can test the barometer component?

My APM 2.5 was working well until yesterday, when the barometer altitude began reading -22 million meters. The GPS altitude is correct.

I've not changed anything major, and not had any serious crashes, so I'm wondering if the part is bad.

I'm running Arducopter 2.9.1 in a 3DR Quad.

I've run the altitude test from the CLI in Mission Planner. Here's what I got:

alt: 0cm, pres:99731mbar, temp: 309/100degC, raw pres:8772901, raw temp 8128156

Any suggestions?



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  • Hello Friends,
    Problem solved the barometer in Arduflyer RcTimer V2.5.
    First deleted the eeprom, the Mission Planner updated to version 1.2.98 and installed V3.1.2 Fw Arducopter Quad, did compassmot, calibrated the barometer and everything returned to normal, did alt hold and loiter, were perfect.
    Re-put the foam like this on the APM website.
    The problem was the firmware
    I want to thank you for your attention.
    Thank you all.
    • Hi Roberto-I am having issues with barometer also and the altitude starts normally and then starts dropping off to negative altitudes even though copter is at relatively stationary altitude. How did you end up erasing the eeprom and reinstalling firmware. Did you just reinstall thru Mission Planner?

      • Hello @all

        i have a similar issue with my baro.

        I have an APM 2.5.

        It seems that the temperature compensation is not working anymore:

        I saw the effect in the mission planner, while the apm was on my desk connected via USB. The altitude was drifting away 10.. 20 m.

        I tried a few things: erase eeprom with the cli , reflash old firmware, reflash current firmware in MP and APM Planner... nothing helps.

        Attached a little trace, where I heated up the APM on a warm surface very fast to have a short trace. 

        As you can see, the altitude drifts 50 m with 5 degree celsius. This is nothing to have in the air, isn't it?

        I would be glad , If somebody has any suggestions how to fix this.

        Or is the baro just damaged?

        Where is the temperature compensation implemented? Is it the barometer itself or is it in the arducopter software?

        Best regards, Felix

        Alt: -0.10m, Raw: 207516.3 Temperature: 27.3

        Alt: -0.37m, Raw: 207522.6 Temperature: 27.3

        Alt: -0.59m, Raw: 207527.9 Temperature: 27.4

        Alt: -1.12m, Raw: 207540.4 Temperature: 27.4

        Alt: -1.64m, Raw: 207552.7 Temperature: 27.5

        Alt: -1.95m, Raw: 207560.1 Temperature: 27.5

        Alt: -2.35m, Raw: 207569.4 Temperature: 27.6

        Alt: -2.97m, Raw: 207584.1 Temperature: 27.6

        Alt: -3.71m, Raw: 207601.5 Temperature: 27.7

        Alt: -4.09m, Raw: 207610.6 Temperature: 27.7

        Alt: -4.58m, Raw: 207622.2 Temperature: 27.8

        Alt: -5.32m, Raw: 207639.6 Temperature: 27.9

        Alt: -5.78m, Raw: 207650.6 Temperature: 27.9

        Alt: -6.19m, Raw: 207660.2 Temperature: 28.0

        Alt: -7.07m, Raw: 207681.0 Temperature: 28.0

        Alt: -7.88m, Raw: 207700.2 Temperature: 28.1

        Alt: -8.36m, Raw: 207711.3 Temperature: 28.2

        Alt: -8.88m, Raw: 207723.8 Temperature: 28.2

        Alt: -9.83m, Raw: 207746.2 Temperature: 28.3

        Alt: -10.77m, Raw: 207768.2 Temperature: 28.4

        Alt: -11.34m, Raw: 207781.8 Temperature: 28.5

        Alt: -11.82m, Raw: 207793.2 Temperature: 28.5

        Alt: -12.74m, Raw: 207814.9 Temperature: 28.6

        Alt: -13.80m, Raw: 207840.0 Temperature: 28.7

        Alt: -14.31m, Raw: 207852.1 Temperature: 28.8

        Alt: -14.84m, Raw: 207864.5 Temperature: 28.9

        Alt: -15.96m, Raw: 207891.0 Temperature: 29.0

        Alt: -17.03m, Raw: 207916.3 Temperature: 29.0

        Alt: -17.52m, Raw: 207927.8 Temperature: 29.1

        Alt: -18.08m, Raw: 207941.1 Temperature: 29.2

        Alt: -19.18m, Raw: 207967.0 Temperature: 29.3

        Alt: -20.29m, Raw: 207993.4 Temperature: 29.4

        Alt: -20.84m, Raw: 208006.3 Temperature: 29.4

        Alt: -21.42m, Raw: 208020.2 Temperature: 29.5

        Alt: -22.55m, Raw: 208046.8 Temperature: 29.6

        Alt: -23.61m, Raw: 208071.9 Temperature: 29.7

        Alt: -24.21m, Raw: 208086.2 Temperature: 29.8

        Alt: -24.83m, Raw: 208100.9 Temperature: 29.9

        Alt: -25.97m, Raw: 208127.8 Temperature: 30.0

        Alt: -27.12m, Raw: 208155.0 Temperature: 30.1

        Alt: -27.74m, Raw: 208169.7 Temperature: 30.1

        Alt: -28.32m, Raw: 208183.4 Temperature: 30.2

        Alt: -29.46m, Raw: 208210.4 Temperature: 30.3

        Alt: -30.61m, Raw: 208237.6 Temperature: 30.4

        Alt: -31.29m, Raw: 208253.7 Temperature: 30.5

        Alt: -31.93m, Raw: 208269.0 Temperature: 30.6

        Alt: -33.10m, Raw: 208296.5 Temperature: 30.7

        Alt: -33.70m, Raw: 208310.8 Temperature: 30.8

        Alt: -34.36m, Raw: 208326.6 Temperature: 30.8

        Alt: -35.43m, Raw: 208351.7 Temperature: 30.9

        Alt: -36.47m, Raw: 208376.4 Temperature: 31.0

        Alt: -37.01m, Raw: 208389.1 Temperature: 31.1

        Alt: -37.67m, Raw: 208404.8 Temperature: 31.2

        Alt: -38.73m, Raw: 208430.0 Temperature: 31.3

        Alt: -39.69m, Raw: 208452.8 Temperature: 31.3

        Alt: -40.32m, Raw: 208467.8 Temperature: 31.4

        Alt: -40.79m, Raw: 208478.8 Temperature: 31.5

        Alt: -41.78m, Raw: 208502.2 Temperature: 31.6

        Alt: -42.75m, Raw: 208525.4 Temperature: 31.6

        Alt: -43.32m, Raw: 208538.7 Temperature: 31.7

        Alt: -43.75m, Raw: 208549.0 Temperature: 31.8

        Alt: -44.73m, Raw: 208572.3 Temperature: 31.9

        Alt: -45.49m, Raw: 208590.2 Temperature: 31.9

        Alt: -45.99m, Raw: 208602.0 Temperature: 32.0

        Alt: -46.31m, Raw: 208609.7 Temperature: 32.0

        Alt: -46.98m, Raw: 208625.5 Temperature: 32.1

        Alt: -47.54m, Raw: 208638.9 Temperature: 32.1

        Alt: -47.78m, Raw: 208644.7 Temperature: 32.1

        Alt: -48.11m, Raw: 208652.4 Temperature: 32.2

        Alt: -48.55m, Raw: 208662.8 Temperature: 32.2

        Alt: -48.89m, Raw: 208671.0 Temperature: 32.2

        Alt: -49.07m, Raw: 208675.3 Temperature: 32.3

        Alt: -49.25m, Raw: 208679.5 Temperature: 32.3

        Alt: -49.53m, Raw: 208686.0 Temperature: 32.3

        Alt: -49.76m, Raw: 208691.6 Temperature: 32.3

        Alt: -49.93m, Raw: 208695.7 Temperature: 32.3

        Alt: -50.03m, Raw: 208698.0 Temperature: 32.4

        Alt: -50.20m, Raw: 208702.2 Temperature: 32.4

        Alt: -50.34m, Raw: 208705.3 Temperature: 32.4

        Alt: -50.36m, Raw: 208706.0 Temperature: 32.4

        Alt: -50.54m, Raw: 208710.1 Temperature: 32.4

        Alt: -50.63m, Raw: 208712.3 Temperature: 32.4

        Alt: -50.68m, Raw: 208713.4 Temperature: 32.4

        Alt: -50.75m, Raw: 208715.1 Temperature: 32.4

        Alt: -50.87m, Raw: 208717.8 Temperature: 32.4

        Alt: -50.91m, Raw: 208718.8 Temperature: 32.4

        Alt: -50.97m, Raw: 208720.3 Temperature: 32.4

        Alt: -51.04m, Raw: 208721.9 Temperature: 32.4

        Alt: -51.02m, Raw: 208721.5 Temperature: 32.5

        Alt: -51.03m, Raw: 208721.7 Temperature: 32.5

        Alt: -51.10m, Raw: 208723.4 Temperature: 32.5

        Alt: -51.08m, Raw: 208722.9 Temperature: 32.5

        Alt: -51.10m, Raw: 208723.4 Temperature: 32.5

        Alt: -51.04m, Raw: 208722.0 Temperature: 32.4

        Alt: -51.08m, Raw: 208723.0 Temperature: 32.4

        Alt: -51.05m, Raw: 208722.2 Temperature: 32.4

        Alt: -50.96m, Raw: 208720.0 Temperature: 32.4

  • I recently started facing issues with the barometer. When I power APM through USB, everything looks fine. But when I connect the battery which powers APM through power module, things go utterly bad. The altitude drops to about -40 meters. I thought, it was the firmware issue, but refreshing the firmware did me no good.

    Here are my test results:
    3692665258?profile=original3692665094?profile=originalI remember that my APM had got heated up, while I was experimenting with additional serial connection from UART2 using FTDI cable. Connecting the power from FTDI resulted in heating up the APM to insane temperatures.

    Without connecting the battery my barometer just works fine. Do I have a reason to believe that I have spoiled my barometer sensor ?

  • I am having the same issue, got the APM installed and tuned and went to fly it, Loiter held position but it kept slowy decending.  Looked at altitude and it was at a constant -70455496.00 feet and will not move.  I opened the case figuring it was the same foam issue - no alt change.  I guess i'll have to reload firmware and hope it fixes it.

  • Yes I found the same solution last night and resolved by erasing.

    I also had a secondary problem where the mission planner showed movements whilst the APM was sat still.

    The erase cured this as well
  • It looks like the component is ok. I erased the EEPROM, reloaded the firmware, and now the readings are correct again. Glad it's not a hardware problem, so I don't have to send in my APM. Would still like to find out what caused the issue, however.

    • Hello David, I am having the same problem with the barometer, when I put in loiter, the quad falls slowly, as if in self landing.

      I have other cards with Megapirate / Mission Planner, and its installation is done via Arduino and there I have the option to erase the eeprom these plates.

      In the case of APM, it is also possible to be done by Arduino or is at Mission Planner?.

      If possible would greatly appreciate your help.

      Thank you very much.

      Roberto-São Paulo-Brazil.

  • I'm having the same symptoms - can't find a solution. Mine is a brand new APM2.5

    I disconnected the compass but same result

  • I'm currently having the same issue. However, my alt starts out at -5cm and continues to fall. After about 5 mins, it falls to -850cm. Whenever I try flying with loiter above my sonar alt, it just goes max throttle and heads for the skies. Any responses from 3DR yet?

    Here is a graph of the data form my latest flight, comparing Baro Alt to Sonar Alt. During the flight, I only flew up to ~40ft, so I don't understand what's going on with my Barometer.


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