Precise Camera Trigger

Hi, I was using a pixhawk running 3.4 dev and was using pin 55 (aux6) as the feedback for the precise camera trigger. It worked fine for pixhawk but I can not seem to get the cam messages to log with Navio2 on RPI3. Is this currently not a working feature? I know on pixhawk you had to set BRD_PWM_CNT= 4 so pins 55 and 56 would accept the trigger signal but there is no BRD_PWM_CNT parameter on Navio2.

Basically i need to know how to configure the feedback pin… I would think pin 55 would be RC14 but no luck

Also i tried setting the feedback pin to 50 which if following the pixhawk pin layout should be RC in 14. Didnt work, so i also tried to set the first relay to 50, AUXOUT1. This cause me to get lockout of my raspberry pi 3 to where I could not SSH anymore. I can get mission planner to connect but not SSH. I reflashed and duplicated the process three times and each time I changed the relay pin to 50 it recreated this issue. I also noticed that navio will no longer log anything even though its set to log all (bitmask 655358) and also any paramter changes I make return to what they were after reboot. Its like everything gets locked out.


It seems like I need to use two of the unused GPIO pins, I’m thinking ADC 4 and 5 are the two unused on Navio2. If someone could guide me in the right direction I would appreciate it. I’m thinking I need to change some code so navio knows to listen for a high and low voltage and change some code in ap camera so it listens on that pin for the cam message log. Again any advice would be greatly appreciated

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@Nikker Hi!

Pixhawk pin layout is not compatible with Navio2.
Currently RC outputs on Navio2 can only be used as outputs.
You can try to use pins 17 and 18 in the UART port. Not 100% sure though that it will work on Linux port - please try and tell if it works.

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Right now the UART port on my Navio2 separated from the board so I am using an osepp USB to FTDI board. I have it working with an RFD900 right now. Is there any way to make it work as an input for the camera trigger? If not, is it possible to allow some of the PWM outputs to be configured as inputs. I used this heavily on my pixhawk and is the only setup issue I have stopping me from retiring my pixhawk flight controller.

Thanks for your help!

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Is there any plan to support rc outputs as inputs on navio2?

@Nikker no, external hardware won’t work with the Ardupilot without the support for it.

@aquila we’ll see what we can do, but it won’t be soon probably.

For anyone wanting a really precise camera time marks I recommend to use Reach - it captures camera feedback with the precision of tens of nanoseconds.


Thanks for the input, unfortunately reach is not a viable option for me. As a surveyor in California I am obligated by law to prove my data at a 95% confidence level and is done by ground control, something we have to do anyways. At this time reach will not let us satisfy this with it alone.

Thanks for your help and input