MP 1.3.32 - Shows Wrong RC PWM Values for Some Channels

Using MP 1.3.32 & APM plane v3.4.0 with a Pixhawk , tested on two different Win7 computers & with direct USB connection as well as wireless telemetry connection.

The Radio-Calibration tab in the Intial-Settings screen shows the wrong PWM values for RC input CH 2 (Pitch) & CH 4 (Yaw).

As far as I can tell the radio calibration function works properly for all channels and I did not notice any discrepancy until I adjusted some neutral trim values.

In my case, the Status-Tab of the Flight Data screen reported the correct values but since the font size is small, I decided to use the Radio-Calibration tab , as it is easier to see, and found that CH 2 was 30 uSec lower in the Radio-Cal tab & CH 4 was 24 uSec lower.
Btw…Those two channels are the only ones that have reverse travel & all channels have 30 uSec of deadband.

I may try to reproduce this with a spare Pixhawk, but I suspect that it is just a typo in the MP code…


Further testing…
Using a spare Pixhawk with a spectrum satelite RX I was initially unable to reproduce the curious discrepancy in my O.P. [ That setup is a Pixhawk , installed in a plane and the RX is a Futaba R7008. ]

However, after copying the parameters to the bench-test -Pixhawk , I once again saw similar differences between the values in the Radio_calibration Tab & the others…
The “others” being… The Status Tab of the Flight-Data screen & the FailSafe Tab of the Initial_Setup screen.

In this case focusing on CH2 - elevator:
RC2 - Trim = 1514 ; Max = 1914 ; Min = 1113 ; DZ = 30 & rev = -1

The RC radio CH2 outputs are: Max = 1914 ; Min =1113 : Neutral stick = 1514 - no mixes , no expo.

In the Radio_ Calibration screen the CH2 values show : Max = 1887 ; Min =1085 ; Neutral stick = 1486.

If I UN-check the Reverse [RC2_Rev = 1] check box for CH2 the values show exactly correct! , that is the values match the true TX output. …and when I “re-check” the box [RC2_REV = -1] the incorrect values are once again displayed … But only after some movement from the stick otherwise the current (wrong value) is not updated on the screen until there is a change in the RC PWM value, this is true for the neutral position as well as for full stick up/down deflections.

I don’t think this is an indication of something being wrong in the Pixhawk software, but simply just an artifact of the the way that the PWM vaules are displayed in Mission Planner.


Try APM Planner2 and you will know :slight_smile:

I tried APM Planner2 and it (Radio-Calibration) shows the proper PWM’s .
So I re-calibrated the radio settings with APM Planner2 & checked Mission Planner and there is no change in it’s readings.
Just to be clear, this only shows up in the Radio_calibration window of Mission Planner.

Since I had the time ,earlier today, I re-installed the APM-Plane firmware in the Pixhawk. I first installed the Copter firmware & then the Plane firmware so that the parameters would get properly ‘wiped’ clear, and I used the “wizzard” to set up the Pixhawk again.
There was no change.