MAVLink: add support for the AVAILABLE_MODES message

[IamPete1]

This message allows the GCS to get the list of available modes at runtime. In the future this allows things like #28110

This requires: ArduPilot/mavlink#374

This message is supported by the QGC daily build and has been tested using it.

For example if you connect to a plane without Quadplane enabled it will only show the fixed wing modes:

If you enable quadplane and re-connect you will then see all modes:

Current master shows a preconfigured subset of modes:

Editing a mode name in the cpp proves that it is updated with the new message:

Future work (not for this PR):

• Fillout the message more completely:

  • Set MAV_MODE_PROPERTY bitmask for each mode.
  • Set MAV_STANDARD_MODE enum for each mode

• Report the current mode with the new CURRENT_MODE message

• Send AVAILABLE_MODES_MONITOR to allow the GCS to notice and re-request if the number of modes changes.

• Support MAV_CMD_DO_SET_STANDARD_MODE

• Addition of new modes from scripting and more.

[Ryanf55]

Why copy-paste twice?

[IamPete1]

Once is for auto RTL mode the other is for auto mode. Auto RTL is not a full mode, just auto mode with a some hacks so it presents as its own mode.

[Ryanf55]

Preliminary thoughts, will do a more thorough review tonight/tomorrow.

[Ryanf55]

What sets this rate, and did you consider making only send the mode on chance?

[IamPete1]

You can request the full list be sent where it would use this rate. QGC actually just requests the modes one at a time, so the stream rate doesn't really mean anything, it would be the SRx_PARAMS parameter.

[amilcarlucas]

Binary Name      Text [B]        Data [B]     BSS (B)        Total Flash Change [B] (%)      Flash Free After PR (B)
---------------  --------------  -----------  -------------  ----------------------------  -------------------------
arducopter-heli  572 (+0.0314%)  0 (0.0000%)  -4 (-0.0015%)  572 (+0.0314%)                                   141000
antennatracker   576 (+0.0427%)  0 (0.0000%)  0 (0.0000%)    576 (+0.0426                                   613348
arducopter       576 (+0.0316%)  0 (0.0000%)  0 (0.0000%)    576 (+0.0316%)                                   140544
ardurover        444 (+0.0266%)  0 (0.0000%)  -4 (-0.0015%)  444 (+0.0266%)                                   294592
arduplane        564 (+0.0310%)  0 (0.0000%)  -4 (-0.0015%)  564 (+0.0310%)                                   143768
blimp            456 (+0.0332%)  0 (0.0000%)  0 (0.0000%)    456 (+0.0332%)                                   591440
ardusub          540 (+0.0335%)  0 (0.0000%)  4 (+0.0015%)   540 (+0.0334%)                                   350220

[Ryanf55]

Binary Name      Text [B]        Data [B]     BSS (B)        Total Flash Change [B] (%)      Flash Free After PR (B)
---------------  --------------  -----------  -------------  ----------------------------  -------------------------
arducopter-heli  572 (+0.0314%)  0 (0.0000%)  -4 (-0.0015%)  572 (+0.0314%)                                   141000
antennatracker   576 (+0.0427%)  0 (0.0000%)  0 (0.0000%)    576 (+0.0426                                   613348
arducopter       576 (+0.0316%)  0 (0.0000%)  0 (0.0000%)    576 (+0.0316%)                                   140544
ardurover        444 (+0.0266%)  0 (0.0000%)  -4 (-0.0015%)  444 (+0.0266%)                                   294592
arduplane        564 (+0.0310%)  0 (0.0000%)  -4 (-0.0015%)  564 (+0.0310%)                                   143768
blimp            456 (+0.0332%)  0 (0.0000%)  0 (0.0000%)    456 (+0.0332%)                                   591440
ardusub          540 (+0.0335%)  0 (0.0000%)  4 (+0.0015%)   540 (+0.0334%)                                   350220

It could be wrapped in an ifdef to reduce impact

[IamPete1]

It could be wrapped in an ifdef to reduce impact

It could, but I think it should be defined in by default. This allows the GCS to accurately relay the modes the vehicle has. This is important on low flash boards where modes are likely to be removed to save flash. Plane vs Quadplane for example.

[hamishwillee]

Very cool @IamPete1

Note, we recently merged the rtl and safety return standard modes, which may affect this mavlink/mavlink#2191

[IamPete1]

Very cool @IamPete1

Note, we recently merged the rtl and safety return standard modes, which may affect this mavlink/mavlink#2191

Thanks! Although we support the available modes stuff we don't do the standard mode thing yet. Everything is still "custom". But I think we will in the future.

[hamishwillee]

Thanks @IamPete1 . I'm hoping you do too - better for the GCS and for users.