A free and open source tool to trigger cameras using Pixhawk and Raspberry Pi (Tested on raspberry pi 3 model b+ and pixhawk 4)
MavSDK (To get telemetry info from the drone to geotag) https://mavsdk.mavlink.io/develop/en/index.html
ExifTool (To geotag images) https://exiftool.org/
wiringpi (To read triggers) http://wiringpi.com/
gphoto2 (To trigger the camera and transfer images) http://www.gphoto.org/
cmake https://cmake.org/
Check performance of Exiftool vs Exiv2
Install and Build ExifTool as follows
Download at: https://exiftool.org/Image-ExifTool-12.10.tar.gz or https://exiftool.org/index.html
Run these steps, adjust for version
cd <your download directory>
tar -xf Image-ExifTool-12.10.tar.gz
cd Image-ExifTool-12.10
Now you can use ./exiftool to run the program, but we need to run it from another piece of code
So we run
perl Makefile.PL
make test
sudo make install
Install libgphoto2 and gphoto2 by following https://github.com/gphoto/libgphoto2/blob/master/INSTALL
On your drone (Using QGroundControl)
Follow the instructions listed here to setup your camera https://docs.px4.io/master/en/peripherals/camera.html.
Set Trigger mode to 4 (Distance, Mission Controlled) and set Trigger interface to GPIO
Follow the instructions listed here to setup telem2 port for mavlink https://docs.px4.io/master/en/companion_computer/pixhawk_companion.html
Connect the AUX pins set for triggering to board pin 16 (gpio 23) of the raspberry pi
Connect the telemetry cable between telem2 to port and raspberry pi as follows
| TELEM Cable | BCM GPIO Pin Number | Board Pin Number | Remarks |
|---|---|---|---|
| 1 VCC | - | - | (As per PX4 documentation you are strictly not supposed to connect this) |
| 2 TX | GPIO 15 | 10 | |
| 3 RX | GPIO 14 | 8 | |
| 4 CTS | GPIO 17 | 11 | (Optional. Yet to be tested if this matters) |
| 5 RTS | GPIO 16 | 36 | (Optional. Yet to be tested if this matters) |
| 6 GND | GND | 6,14,20,30,34 |
To Build the MavSDK repo on the raspberry pi follow the steps at https://mavsdk.mavlink.io/develop/en/contributing/build.html#build_cpp_linux
On step 5, instead of the provided cmake command use this one
cmake -DCMAKE_BUILD_TYPE=Debug -DBUILD_SHARED_LIBS=ON -DCMAKE_SHARED_LINKER_FLAGS='-latomic' -Bbuild/default -H.
To Build the PixTrigger repo, use these commands
mkdir build && cd build
cmake ..
To run (From the pixtrigger repo)
./pixtrigger.sh