CAM_TRIGG_DIST in servo mode on Pixhawk outputs erratic PWM

I have extensively tested today the CAM_TRIGG_DIST functionality on Pixhawk, in servo mode (not relay mode). This means , if it weren’t bugged, that Pixhawk should output the maximum PWM value (as defined in camera gimbal parameter screen in mission planner) on ouput AUX1 (RC9) when the multicopter has moved CAM_TRIGG_DIST meters away (defined in full parameters list). If the multicopter does not move, the AUX1 (RC9) should output the minimum PWM value (as defined in the camera gimabl parameter screen).
However, connecting my PWM analyzer on AUX1 (RC9) of pixhawk shows that erractic PWM values are constantly changing on Pixhawk output AUX1 (between min and max values), and thus AUX1 does not behave as it should according to the CAM_TRIGG_DIST functionality.
This is very frustrating as it is the only good way to do ortho mapping and photogrammetry.

I already have read that CAM-TRIGG_DIST did not work in relay mode on PIxhawk in the current firmware. Can a developer confirm that it also does not work in servo mode in the current firmware (V3.1.2) ??
Or did I miss something ?

Hi Hughes,
I can say that I have been successfully using CAM_TRIG_DIST function on the current code on a pixhawk and not noticed your issues,… BUT they way I am doing it may be a little different. I have made a arduino pro mini board that receives a pwm from the pixhawk and then sends the first signal low for 0.05 seconds (focus pin on the camera, needs to be pressed to enable the shutter relesae) then adds in a low signal to a second pin to take the shot. unit set to trigger at 1600 onthe arduino board, pixhawk set to 1100 open, 1900 close for 0.5 seconds

Might be able to get out this afternoon and put a servo on the pixhawk output and record the position with a gopro and see what it’s actually doing…
I guess this is a good case for HIL testing, which admittedly I have never done!!

Actually I just remembered that I was getting the odd false trigger or un-commanded trigger using the APM 2.5 a while ago,… that was with do_digi_command maybe that might be tied in as well? thought it might have been a floating pin on the arduino board I made, I am thinking now that is not the case as it hasn’t happened since I installed the pixhawk…

Hi Steve,
I am interested about your hardware and software config that you use to have cam-trigg-dist work. How do you output a PWM signal from pixhawk? (Which config in MP? Aux1 ? Ch7? Which CaM-trigg param? Etc)

Is it confirmed? Does Cam_trigg_dist on a servo output not work on the pixhawk without using a separate Arduino board?

The Pixhawk output 3.3V. You need some kind of level shifter to make it work.


I’m talking about the servo outputs not the relay outputs. I should be able to use the output servo rail to power the IR trigger, if not, I can use external power and just use the servo signal and ground pin.

The original question was about erratic PWM using CAM_TRIGG_DIST in servo mode.