Pixhawk relay function - relay 2 does not function in copter 3.3.3

ArduCopter Copter 3.3
1

I’ve made a gopro controller which uses 2 separate pins - 1 for trigger/shutter & 1 for switching modes.

I’m using momentary switches (On Taranis - SH, and I’ve changed SD out to a momentary as well).

I originally did this on the FC I was running 3.4 rc on, and had no issues (other than finding which function actually allowed control of relay 2 which isn’t very well documented).

So my brother wanted one…I made it and put it on, and couldn’t get it to work.
Tried everything…nothing. His FC is a 3DR Pixhawk - running 3.3.3.

My FC suddenly lost motor 2 signal for some reason…so I replace with new Pixhak non-3DR. Used the mission planner setup wizard and loaded 3.3.3.
I went ahead and configured everything from scratch. Camera trigger on Relay 1 works…Relay 2 doesn’t work.

So I fool around with it and nothing. I decide to load 3.4 RC just to see and viola! Relay 2 control again.
Load it up on my brother’s and bam…starts working.

So after the long explanation…it appears the relay 2 function - or at least function the way I feel a relay should be working - has not worked in 3.3.3, and 3.4 has fixed it.

2

Only one relay can be controlled by radio even if you have more that one realy enabled in your configuration.

I don’t know if that changed with 3.4 but until 3.3 it is normal.

3

Yeah I got it figured out now - on 3.4 RC. Never could get the second one to work however.
You can issue Mavlink commands to do it through MP, but that’s not what I was wanting to do.

With 3.4, DON’T change any AUX RC_XX value. It needs to be set to 0 for any RC9-14 you’re using for a relay.
then assign the relay function to ch_xx_opt 28 for first relay (unless you’re using camera trigger), 34 for second, 35, 36 etc.