You are right: in both ROI changes there is a single message showing not only a glitch on RCIN.C4 but also value changes in C1, C3, C5, C6 and C7 (not in C2 ???). So surely this is related to the problem. Anyhow, I am not sure of what would happen if you change yaw with a stick during a mission (I am certain that changing throttle does nothing), but will try this next time.
The transmitter in this case is a Futaba 7C. C5 is on two switches for mode change (channel 5), C6 is a knob (potentiometer, channel 6) for gimbal pitch (unused), and C7 is on a switch. RCIN.C6=0
, as appear in the message, would be impossible to get.
These ROI changes have been observed on different Arducopter versions and vehicles (first on Tradheli, with a Futaba T8FG), and using two different Futaba 7C transmitters.
Receivers used are FrSky TFR4-B in all these cases.
I didn’t move the sticks while in the mission. Otherwise, it would be impossible to manually do such a small instantaneous change on a stick, a knob and at least two switches, precisely with copter in north orientation.
These are the relevant configuration parameters:
For RCIN.C5=1482 mode is Auto. For RCIN.C5=965 (glitches) mode would be AltHold during an instant, but mode is not changed.
So unless admitting that two different Futaba transmitters (7C (Copter) and T8FG (TradHeli)), or three different FrSky TFR4-B receivers, produce sometimes somekind of simultaneous channel glitches, precisely when the controlled vehicle is oriented north, and simultaneously somehow producing RCIN.C6=0 and RCIN.C7=0, there must be other explanation.
Anyhow, since 1516-1092=24 > 20=RC4_DZ, I will change RC4_DZ=30 and keep observing.