Erratic altimeter readings on ArduCopter 2.5.5

Hi Everyone,

I recently setup a new hexacopter and loaded ArduCopter 2.5.5.  I'm using an APM 1.  After plugging in the battery and using wireless telemetry to connect to the Mission Planner the altitude readings are all over the place:

3690939433?profile=originalThis does not happen when connecting directly via USB.

The only workaround I've found so far is to turn on my hexa and make an initial link via USB.  I then disconnect and reconnect via wireless telemetry...which is a pain since I have to remove and reattach the dome every time.

Any ideas?

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  • Rigel,

    I have the same problem.  Normal baro without 900 Mhz Xbee connected - plot similar to yours with Xbee connected. 

    I was also wondering if this was related to 2.5X since I haven't seen this issue before. 

    Now onto troubleshooting and will report back if I learn anything. 

  • Moderator

    Yeah, you might not have to give up on the 900Mhz entirely. If you want to keep it, look at moving the RX farther way from the Xbee (sometimes these two interact and cause problems together.... I know, an RX is not supposed to transmit, but they do, sometimes, when near a VTX or Xbee.) and look at shielding some of the exposed cables.... it might be your sonar cable, or GPS cable or any cable (did you say you have a magnetometer? I believe that is i2c, and I believe the barometer is i2c also) that is getting a signal from the Xbee and causing fluctuations on the bus used by the barometer. I'd suspect the i2c devices and wires first.... Is your mag soldered to the board, or attached with a cable?

  • I have the exact same problem, thats almost identical to my alt graph thismorning. logs show that ots the sonar, wirh very bad noise. seems to be crosses up with thr gyros or something because its relatively quick movements that make it worse, slowly tilting the quad does nothing and tapping the bars with ascrewdriver does nothing. ill post my log files when i get home. 

  • Moderator

    Odd. As a test, try creating a longer telemetry cable and placing the telemetry model farther away from the APM1. See if that makes any difference. 

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