Payload drop and servo pwm setting in mission mode


i tried to use the qgroundcontrol setting (mission) to activate a servo to a specified PWM setting, but got no response (that was noticeable.
servo # in mission waypoint menu was “0”, pwm was 775.
pwm setting was 775, which was set in “min” for the aux1 servo (default remained at 1000)
i had rc channel 8 mapped to (passthru) aux1 for some tests, for others i unmapped the rc from aux1.
the servo works when controlled from the RC Tx even in mission mode. (if it is mapped in qgroundcontrol).
how do i use the payload drop commands (BD_*) ?


What Pixhawk are you using? What version of PX4 are you using? What is the exact mission? What airframe and mixer configuration have you selected?


hi @JulianOes,
CUAV Pixhack V5
px4 1.9.0
qgc 3.5.3
mission: RWTO; WP1=TO; WP2=WP; WP3=loiter(time); WP4=WP;WP5=WP;WP6=Set Servo=Servo 0, PWM 775; WP7=WP; WP8/9=Landing pattern.
Airframe: basic plane
mixer config: What you talkin bout, willis?
btw, I tried another method… using camera trigger on WP setting, camera trigger to aux1. camera trigger works when ‘tested’ (qgc camera page), but mission doesn’t.


Ok. I don’t think the do_set_servo command for the mission is supported, so that could explain the problem.
Can you try the camera trigger in the mission then?


yes. I did try the camera trigger (seend of previous post). it works when the qgc ‘camera test - “trigger camera”’ button is pressed (before arming), but mission with neither a start image capture WP or a WP with a camera trigger added produce servo activation. Actually, when I land and disarm, even the qcg “camera test - trigger camera” button won’t trigger servo movement any more. FC needs to reboot to reactivate.
I just noticed (running tlog) that I didn’t check the “mode” box in the camera add for the WP item. it is grayed out with “photo”, so I assumed it was ok. now, when I check that box, subsequent mission items’ numbers increment. I wonder if that will have an effect.

is there a parameter or “mapping” that i’m not aware of? tthen why would the test work but mission not?
trig_interface : generic pwm
trig_mode: time base, on command
trig _act_time: 3000ms


No joy checking the"mode" box either. Couldn’t get any mission controlled servo to work at all. Can’t figure it out.


So have you tried to use the camera trigger as part of the mission?


is that different than what i mention in post#3 and post#5 ? i’ll take look and see if i can find a different option in the mission definitions.