I have V 2.9.1b loaded.  I configured channel 7 to be RTL when Pulse Width high. Low position produces pulse much shorter than value to change to RTL.  High position produces a pulse much longer than RTL. So all should work as advertised. I have no radio glitches   But as I fly with Mission Planner connected with 3DR radio telemetry, Mission planner keeps announcing changes to RTL without any change in channel 7  (always in the the low position - I.E.  RTL not enabled).   The mode goes to RTL then back to the previous mode (Stabilize, Altitude Hold, etc) 4 to 8 times in a 5 minute flight.  The logs indicate the RTL mode only lasts a very short time  (see below).

Flying in Stabilize and Altitude Hold modes seems OK even though this is going on but I really do not want to fly with this going on.  

Is this channel 7 set for RTL behavior normal?  

 Here is what actually happens (from flight log)

....(lots of log before)

NTUN, 908, 243, -727, -368, 1241, 3258, 452, 552
CTUN, 629, 0, 1331, 1475, 0, 34, 94, 553, 18
EV: 15
MOD:ALT_HOLD, 432   <  I actually changed to Altitude hold here
ATT, 0, 2162, 0, 968, 0, 13568, 13692
CTUN, 623, 0, 1342, 1476, 0, 33, 95, 526, 14

....more log

CTUN, 627, 0, 1334, 1507, 0, 51, 67, 612, 16
ATT, -513, -577, -3188, -2589, 0, 13589, 13692

EV: 15      <--  I did not touch the channel 7 switch but this sequence happens
EV: 29
MOD:RTL, 432    <-- MP announces change to RTL
DATA: 7, 13505
CURR, 626, 275781, 11.0300, 26.2900, 313
CTUN, 612, 0, 1335, 3048, 0, 36, 75, 484, 0
ATT, -440, -461, -3188, -2577, 0, 13589, 13692
GPS, 72495000, 12, 35.1228460, -106.2545860, 14.6200, 2091.2300, 691, 1615
NTUN, 121, 80, 107, 19, 0, 0, 119, 390
CTUN, 624, 0, 1341, 3048, 0, 31, 65, 439, 0
ATT, -367, -326, -3088, -2578, 0, 13610, 13692
EV: 15
EV: 28      <--  It goes back to Altitude hold all by it'self  I did not touch any switch
MOD:ALT_HOLD, 432     <-- MP announces change to Altitude hold
CTUN, 626, 0, 1347, 1459, 0, 32, 46, 455, 16
ATT, -391, -262, -2967, -2544, 0, 13651, 13692

....  more log  and more similar changes to RTL then Back at random times


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  • I have narrowed down the problem.  I am using a Spectrum DX8 transmitter and a Spectrum AR8000 8 channel receiver.  The channel 7 value in the APM glitches to a high pulse width randomly - about every minute or so, sometimes  more often.

    Simple fix:  Switch DX8 transmitter from 22 ms frame rate to 11 ms frame rate.   No more issue:

    This could be an issue with my (all) DX8 8 channel receiver or with the APM2.5 PPM Encoder.  Turns out the throttle channel also glitches from time to time.  The glitching goes away if I disconnect channel 5 from the AMP temporarily using 22ms frame rate.

    To figure out where the problem is I will have to put an oscilloscope on channel 7  (and or throttle) to see if glitch happens before the PPM Encoder (radio output) or just in the read_radio output (after the PPM Encoder).

    Thanks to Mike for steering me in this direction.  

    Stay tuned.

    Found the hint and solution here.  Also how to use radio calibrate to see radio glitches. Read that for more details.


  • It definitely sounds like radio glitching.

    What radio are you using?

    Can you post any logs?

    Do you have RTL configured for battery?

    Do you have RTL configured for throttle?

This reply was deleted.


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