AP_Mount: add CADDX gimbal support

[rmackay9]

This is a simplified version of @Hwurzburg's previous PR #28373 to add support for the CADDX GM3 gimbal

This simply adds support for the gimbal without trying to support the extra lock types that the gimbal provides. These extra lock types add the ability to control each axis (roll, pitch and yaw) in earth or body frame independently. For example roll control could be in body frame while pitch is in earth frame. This new ability is not supported in this PR.

This has been tested on real hardware and seems OK.

The corresponding wiki PR is here ArduPilot/ardupilot_wiki#6441

[Hwurzburg]

why drop the lock types and control?

[rmackay9]

Hi @Hwurzburg,

I dropped the lock types and control because I couldn't get them to work and also they are really an enhancement so they naturally fall into a follow-up PR that could potentially affect other gimbals as well. The Siyi gimbal for example also supports FPV mode and users have been asking for that for a long time so we could do the two together

[Lalbabu2001]

Hi please add support for this board
https://www.6sfull.cz/en/neutronrc-mini-f405-2-6s-20--20-30--30/

Don't forget to add Bmp 280 baro because new versions come with bmp280.
Also add support for PPM .
Thanks.

[rmackay9]

Hi @Lalbabu2001,

I've created an issue here to capture this enhancement request #28945. No promises on when/if it will be done though. I'm not personally very experienced porting AP to new boards.