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Using AUX pins as relays for CHDK

Posted by Dave Williams on February 11, 2014 at 12:39pm

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

      • Wiki Ninja
        Hamish Willee > Thorsten July 5, 2015 at 5:30pm

        Hi Thorsten

        > I'll try it for sure and I hope they'll place it in the wiki!

        Who is this "they" you speak of :-) Were you thinking this should be added here? I don't think this can be added as is - minimally should have labels or diagram which shows what components go where on the pcb. Did it work OK?

        Cheers

        Hamish

        • T3
          Thorsten > Hamish Willee July 6, 2015 at 12:36pm

          Hi Hamish,

          Who is this "they" you speak of :-)

          The power, the force, the motion, the drive! :-) 

          You guys are doing a brilliant job on the wiki! Thanks!

          The problem with this circuit stuff is that it is not straight forward to build your now board based on Marco's circuit or the derived version which is now posted on the wiki. Hence, a while back, I posted a more detailed how-to.

          But now I saw the Za Pf's brd files which he made available on OSH Park. I haven't tested it so far (just ordered it) but I think this is the way to go. And before it gets lost in the "Ning-space" I hope that it will be placed more prominent. I agree more details are required.

          The design is from Reuben and is based on two 220k resistors and one 547 transistor. 

          I'll post some details when I tested it.

          Cheers,

          Thorsten

      • Za Pf > Thorsten June 30, 2015 at 11:48am

        Again, I must stress that this is not my design. This was posted earlier, and there is an example from Brian Christal on the previous page. I just wanted to make one as cheap and easily accessible as possible.

        • T3
          Thorsten > Za Pf June 30, 2015 at 12:16pm

          Hi Za Pf,

          I know. There have been lots of reposts here and everything is a little chaotic.

          You posted the brd files and that really makes things easier!

          Thanks to everyone who contributed!

          Thorsten

  • Plinio Augusto June 4, 2015 at 1:14pm

    Hello everyone,

    Hhow to solve the delay problem in shots on CHDK? When the signal is sent to camera takes a while to shoot, there is a way that shooting happen faster? Perhaps for this reason Ebee uses Canon without CHDK. Probable Ebee connect the trigger cable directly to the canon shutter button. We realize the difference by aligning the blue and green balls during image processing in Pix4D. Any help is welcome.

    Regards,

    • Brian Christal > Plinio Augusto June 4, 2015 at 2:02pm

      Chasing the camera delay from CAM trigger message to shutter open is futile. Feedback from the camera to the autopilot is required. It's being addressed here:

      https://github.com/diydrones/ardupilot/issues/2289

      http://chdk.setepontos.com/index.php?topic=12398.0

      Brian

      • Plinio Augusto > Brian Christal July 5, 2015 at 6:53pm

        Hi Brian,

        I have a Canon SX260... You know any way to adapt external flash to catch the feedback signal in this model? I also think of using the IXUS 155 20 mp...

        Regards,

        • Brian Christal > Plinio Augusto July 5, 2015 at 7:17pm

          Hi Plinio,

          Yes, sort of. There is a beta version of the KAP UAV script that lights the red eye lamp when the shutter opens. I'm working a cable now that uses a phototransistor to read the lamp and send a feedback signal to the Pixhawk. But, the cable is not ready yet, nor is the ardupilot firmware.

          I don't think CHDK is available for your IXUS 155.

          Brian

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