Using AUX pins as relays for CHDK

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?

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Replies

                • Hi Craig,

                  Did these ever become available in the store?

                  This is a real Pixhawk killer for me. The APM does everything I need without modification.

                • Good news! thanks Craig.

                  • Update, finally got it working, could only get it to trigger using a relay command.

                    CAM_TRIGGER_TYPE 1
                    CH7_OPT 9
                    RELAY_PIN 50

                  • Help guys please, made the circuit yesterday, connected it up and it fired the camera within seconds, thought I was on a winner, but it fires the camera just randomly.  I have it set for every 5 metres, but when I walk for at least 30m nothing happens, place it back on the ground to think about it, it fires. So I pick it up and start walking and it fires at 5 times in quickly. I am using AC 3.1.5 with these settings (same as Carl)

                    BRD_PWM_COUNT = 4  (Aux 1-4 setup as "servo" PWM outputs and Aux 5-6 as "relay" or digital outputs)

                    CAM_DURATION = 10 (1 second)

                    CAM_SERVO_OFF = 1100

                    CAM_SERVO_ON = 1800

                    CAM_TRIGG_DIST = 5 (meters for indoor testing)

                    CAM_TRIGG_TYPE = 0  (servo or PWM output)

                    RC11_FUNCTION = 10 (camera trigger) 

                    I am not an electronics expert, here is a pic of my board, what tests can I do on my board to see if it is ok, I confirmed I have 5v in and 0v out.

                    What am I missing?

                    Trigger.jpg

              • It is a shame, spent many hours trying to get it to work here as well, making the circuit today, hopefully it will work for me

    • Developer

      Just for security put a little fuse on the 5V.

      • A fuse amperage?
      • From power source to the middle AUX pins?

This reply was deleted.

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