Docs: page is missing

[hbaklan943]

The following template is for Issue/Bug reporting only. https://docs.qgroundcontrol.com/en/support/support.html#github-issues

For questions about how to use or build QGC see: http://qgroundcontrol.com/#resources

If you are using an old stable release please upgrade first and verify your issue before reporting.

Expected Behavior

QGC docs says that we can choose the used dialect by modifying MAVLINK_CONF. it should redirect to proper location where MAVLINK_CONF defined.

Current Behavior

MAVLINK_CONFIG redirects to a non existing page.

Steps to Reproduce:

Please provide an unambiguous set of steps to reproduce the current behavior

1. go to https://docs.qgroundcontrol.com/master/en/qgc-dev-guide/custom_build/mavlink.html
2. on the bottom you will see: (You can change the whole dialect used by setting it in MAVLINK_CONF when running qmake.)
3. click the link

System Information

When posting bug reports, include the following information

• Operating System: [Ubuntu 22.04]
• QGC Version: []
• QGC build: [e.g., daily, stable, self-built from source, etc...]
• Flight Controller: [Pixhawk 2,]
• Autopilot (with version): [PX4]

Detailed Description

Provide further details about your issue/bug.

Log Files and Screenshots

[hamishwillee]

@DonLakeFlyer This is correct - MAVLINK_CONF used to be defined in QGCExternalLibs.pri, but that file no longer seems to exist.

[HTRamsey]

Needs to be updated for CMake, it will instead be CustomOptions.cmake

[hbaklan943]

Also the same section of the page says that
"QGC uses a pre-built C library that must be located at /qgroundcontrol/libs/mavlink/include/mavlink in the QGC source."
but even after I delete those pre-built C libraries and launch the qgc, it still continues to successfully receive mavlink messages.
There seems to be another problem about this too.

Another question if anyone willing to help: Where are the mavlink message definitions located at in qgc source code, I couldn't find it.

[hbaklan943]

new findings from me. tldr; i guess when building qgc it fetches pre-built mavlink libraries from a git repo

cmake/CustomOptions.cmake

set(QGC_MAVLINK_GIT_REPO "https://github.com/mavlink/c_library_v2.git" CACHE STRING "URL to MAVLink Git Repo")
set(QGC_MAVLINK_GIT_TAG "4db2f67156d996eae90ef437a73353468d850407" CACHE STRING "Tag of MAVLink Git Repo")

src/MAVLink/CMakeLists.txt

FetchContent_Declare(mavlink
    GIT_REPOSITORY ${QGC_MAVLINK_GIT_REPO}
    GIT_TAG ${QGC_MAVLINK_GIT_TAG}
)
FetchContent_MakeAvailable(mavlink)

target_include_directories(MAVLink
    PUBLIC
        ${mavlink_SOURCE_DIR}
        ${mavlink_SOURCE_DIR}/all
        ${mavlink_SOURCE_DIR}/common
)

I will try to make it fetch from a repo that i created with my custom message definitions. If it works i may try to update docs.

edit: it indeed fetches message definitions and c header files from the git repo. Should i close the issue or make a pr to the docs

[hamishwillee]

Thanks @hbaklan943 Even if it fetches the repo, you'd still need to select the dialect to use. So that must be specified somewhere.

[hbaklan943]

Thanks @hbaklan943 Even if it fetches the repo, you'd still need to select the dialect to use. So that must be specified somewhere.

I couldn't find where the selected dialect is specified but i didn't had to set anything, I just changed the fetched git repo link and the tag of that repo.

It seem's this is automated in somewhere but i couldn't find where that happens. For now maintaining a git repo for my custom mesages solves my problem.

Also I guess even though we find where the c-headers and definitions located(probably under libs/mavlink/include/mavlink) and change them they will be replaced with the fetched repo on each build.

[HTRamsey]

@hbaklan943 I have not finished with all the custom options like selecting mavlink dialect in cmake yet. But I've been working on it and will add that option soon. As such, the documentation isn't updated either until this is finalized.