Some AUX pwm outputs go lower on arm

[Thijs----]

Describe the bug When the UAV is armed (via RC), some AUX pwm outputs (actuator_outputs_1) shortly go to a lower value, although this is not commanded via an actuator_control message. It seems that this only happens with AUX outputs who's PWM_AUX_DIS is set.

To Reproduce Steps to reproduce the behavior:

1. change PWM_AUX_DIS2 (or another) from -1 to 100
2. (set SDLOG_MODE 0 -> 1)
3. pre-arm UAV via onboard arm-switch
4. arm via RC
5. see in log: during 2nd arming the actuator_outputs_1[1] goes down for a short while

Expected behavior The output should be following the commanded value via the mixer file, thus stay constant.

Log Files and Screenshots Always provide a link to the flight log file:

• 1st log: modified firmware PX4 Flight Review, AUX output chart. PWM_AUX_DIS2 and PWM_AUX_DIS3 set to 100 (AUX output 1 & 2). Note that the lower value is 1050 and ramps up to commanded value. Used mixer: actuator_outputs_1[0] = actuator_control_0[7] (landing gear) actuator_outputs_1[1] = actuator_control_2[1] (mount pitch) actuator_outputs_1[2] = actuator_control_2[4] (mount custom)

• 2nd log: PX4 v1.10.0, vmount enabled PX4 Flight Review, AUX output chart. PWM_AUX_DIS2 set to 100 (AUX output 1). Note that the lower value goes to 100, then 1050 and ramps up to commanded value. Used mixer: mount activated

• 3rd log: PX4 v1.10.0, default mixer PX4 Flight Review, AUX output chart. PWM_AUX_DIS2 set to 100 (AUX output 1). Note that the lower value goes to 100, then 1050 and ramps up to commanded value. Used mixer: default (pass trough?)

Add screenshots to help explain your problem. 1st log: Note that the arming_state is scaled 2nd and 3rd log: Note that the arming_state is scaled

Drone (please complete the following information):

• octo/quadcopter
• PX4 1.10.0

Additional context Add any other context about the problem here.

[dagar]

Could you please re-test this on the current v1.11.0-beta1 (or master)? If it's still an issue I'd like to make sure it's fixed for the upcoming v1.11.0 stable release.

[Thijs----]

I Tested with v1.11.0-beta1: PX4 Flight Review (AUX output chart) Same effect: with PWM_AUX_DIS2 set too 100, on arm AUX output 1 goes down to 100, then 1050 and ramp up to 1500 again.

[Thijs----]

Two updates:

1. I also tested with PWM_AUX_DIS2 set to 1900: on arm AUX output 1 goes shortly to 1900 and direct back to commanded value: PX4 Flight review. So same behavior, except there is no ramp up from 1050.

2. I also noticed during another test that if even no PWM_AUX_DIS is set, this behavior occurs. In this PX4 Flight review the AUX output 0 is commanded to 1000, on arm it goes shortly to 1500 (default disarm pwm).

[stale[bot]]

This issue has been automatically marked as stale because it has not had recent activity. Thank you for your contributions.

[JaCoHSU]

@Thijs---- I am facing the same problem. Is there any solution? I figured out that this happens only at the first arming after boot.

[Thijs----]

Hi @JaCoHSU, I don't think there was a solution or workaround. I can't verify it, because I no longer have access to the project.