MAVLink Custom Message - Where is MAVLINK_DIALECT?

TrueAquarius · May 1, 2023, 7:01am

Dear PX4 Friends,

I am trying to create a custom MAVlink message. I follow instructions on defining-custom-mavlink-messages. These instructions say (quote):

There are are number of XML dialect files in /mavlink/messages/1.0/. The dialect that is built is specified using the variable MAVLINK_DIALECT in /src/modules/mavlink/CMakeLists.txt; by default this is development.xml. The files are generated into the build directory: /build/<build target>/mavlink/

I am not able to find the variable MAVLINK_DIALECT in CMakeList.txt. That string does seem to exist in that file.

Any hint greatly appreciated.
Thanks in advance

JulianOes · May 2, 2023, 8:24pm

Hi!
You might be able to configure the MAVLINK_DIALECT using Kconfig:

github.com

PX4/PX4-Autopilot/blob/60b85c2e1a12b0c366ac736be3ca98011fe5798d/src/modules/mavlink/Kconfig#L7-L12


      
          menuconfig MAVLINK_DIALECT
          depends on MODULES_MAVLINK
                  string "Mavlink dialect"
                  default "common"
          	---help---
          		Select the Mavlink dialect to generate and use.

You can set it for you board in default.px4board, e.g. for SITL:

github.com

PX4/PX4-Autopilot/blob/b6f19d5e9b68b229e6dfe345ebd1f9cf1af22462/boards/px4/sitl/default.px4board#L33


      
          CONFIG_MODULES_GYRO_CALIBRATION=y
          CONFIG_MODULES_GYRO_FFT=y
          CONFIG_MODULES_LAND_DETECTOR=y
          CONFIG_MODULES_LANDING_TARGET_ESTIMATOR=y
          CONFIG_MODULES_LOAD_MON=y
          CONFIG_MODULES_LOCAL_POSITION_ESTIMATOR=y
          CONFIG_MODULES_LOGGER=y
          CONFIG_MODULES_MAG_BIAS_ESTIMATOR=y
          CONFIG_MODULES_MANUAL_CONTROL=y
          CONFIG_MODULES_MAVLINK=y
          CONFIG_MAVLINK_DIALECT="development"
          CONFIG_MODULES_MC_ATT_CONTROL=y
          CONFIG_MODULES_MC_AUTOTUNE_ATTITUDE_CONTROL=y
          CONFIG_MODULES_MC_HOVER_THRUST_ESTIMATOR=y
          CONFIG_MODULES_MC_POS_CONTROL=y
          CONFIG_MODULES_MC_RATE_CONTROL=y
          CONFIG_MODULES_MICRODDS_CLIENT=y
          CONFIG_MODULES_NAVIGATOR=y
          CONFIG_MODULES_PAYLOAD_DELIVERER=y
          CONFIG_MODULES_RC_UPDATE=y
          CONFIG_MODULES_REPLAY=y

You should also be able to set it using menuconfig which can edit the Kconfig options but I couldn’t find just yet.

TrueAquarius · May 3, 2023, 6:22pm

Thanks for your help. I will try.

DaShen96 · June 7, 2023, 6:07am

Hi friend , did you custom mavlink message successfully? I tried to define a message , but I couldn’t capture data on the serial port. Do you have any tips？

JulianOes · June 10, 2023, 7:32pm

You need to make sure the custom dialect is generated and built for all components, so probably PX4 as well as the QGC (or MAVSDK, MAVROS) or whatever you’re using on the ground.