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I'm confused and a bit frustrated, would appreciate any help as I'm not sure how to proceed.

Setup: I have a pixhawk autopilot running Arduplane 2.77, using Mission Planner 1.2.95

I've been following this guide to get my CHDK enabled camera working with my pixhawk. I'm interested in getting the camera triggering based on distance traveled.

Obviously the guide was written with APM in mind, so it needs to be adapted a bit for pixhawk; specifically the setting for RELAY_PIN. I've kept the rest of the settings the same as in the tutorial.

Pixhawk has 6 AUX ports according to the quick start guide, I am assuming that the numbers above the pins correspond to the AUX port numbering. When you mouse over the RELAY_PIN parameter, it says that pin 54 corresponds to Pixhawk FMU AUX1.

Tried setting RELAY_PIN to 54, no joy. Did a bit more looking, discovered in the release notes for 2.77: 

"Improved relay code
The relay and servo set code has had a major overhaul, with up to 4 relays now supported for MAVLink control and much better support for the DO_SET_SERVO, DO_SET_RELAY, DO_REPEAT_SERVO and DO_REPEAT_RELAY MAVLink commands. Along with these changes is a new parameter BRD_PWM_COUNT which allows you to specify how many auxillary PWM outputs to enable, with the remaining outputs being available as digital relays. This allows you to re-assign some of the aux servo outputs on Pixhawk for use as relays, by setting the RELAY_PIN, RELAY_PIN2, RELAY_PIN3 and RELAY_PIN4 parameters. The pin numbers for these pins start at 50 for the first aux servo pin, and go to 55 on Pixhawk."

Additionally,I found this github issue about this same problem that states that the Pixhawk can't trigger CHDK because its relay pins operate at 3.3V instead of 5V.

So i suppose my specific questions are:

1) Is AUX1 pin 50 or 54?

2) Can anyone confirm that the relays, when working properly, won't be able to trigger CHDK?