add paralized mode; detect FC alive

[ligenxxxx]

### Failsafe mode
- When vtx is captured into failsafe mode, vtx is automatically set to 0mw.
- When vtx is in failsafe mode, power on switch and other remote control operations for vtx will be invalid.
- When vtx captures exiting failsafe mode, vtx is automatically set to the power value that was not 0mw last time.
All the above are valid when boot_0mw enable is enabled.

Known problem:
If failsafe is switched on and off quickly in a very short time (less than 1 second), RF settings may fail. This may be caused by some state refreshes being too slow.
I think failsafe mode is not necessary for VTX. If it is forced to be implemented, it may cause users to control the power very complicated, so I decided to remove it.

Paralized mode

• Only valid when team_race is mode1.
• If the FC paralized mode is turned on, the VTX will turn off the RF and go to sleep until repower.
• the VTX will turn off the RF and go to sleep until repower when FC uart_tx doesn't ouptut to vtx.
• During which time the blue led will blink rapidly.

A beta FC FW is needed here. https://github.com/betaflight/betaflight/suites/12066455915/artifacts/634884164

[lesharodin]

So when Flight Controller is in a FailSafe state vtx would go to 0mw, why? Is it optional or would be default behaviour of vtx?

[ligenxxxx]

So when Flight Controller is in a FailSafe state vtx would go to 0mw, why? Is it optional or would be default behaviour of vtx?

This only works when Boot 0MW is on. Mainly it is convenient for team race.

[john-k3nnedy]

This change makes me nervous given that I occasionally have the OSD stop updating mid-flight. I'd assume this might trigger a vtx_paralized()?

[john-k3nnedy]

Should this actually be terminal, i.e. requiring re-power or could we make it a recoverable situation?

[ligenxxxx]

This change makes me nervous given that I occasionally have the OSD stop updating mid-flight. I'd assume this might trigger a vtx_paralized()?

• In team_race mode, the communication between fc and vtx must be maintained, otherwise vtx RF cannot be woken up.
• In team_race mode,, the uart that originally communicated normally loses connection suddenly, VTX will think that FC is faulty, and VTX will turn off RF at this time.

[john-k3nnedy]

This change makes me nervous given that I occasionally have the OSD stop updating mid-flight. I'd assume this might trigger a vtx_paralized()?

• In team_race mode, the communication between fc and vtx must be maintained, otherwise vtx RF cannot be woken up.
• In team_race mode,, the uart that originally communicated normally loses connection suddenly, VTX will think that FC is faulty, and VTX will turn off RF at this time.

Yeah I get that, but it seems risky — normally the FC shouldn’t crash mid-flight and if the connection gets interrupted for some other reason you’ll lose video.

My team mates and I had a couple of times that the OSD stopped updating mid-flight. I suspect the VTX might turn off then with this change, which means I’d not only lose OSD, but also video.

[ligenxxxx]

This change makes me nervous given that I occasionally have the OSD stop updating mid-flight. I'd assume this might trigger a vtx_paralized()?

• In team_race mode, the communication between fc and vtx must be maintained, otherwise vtx RF cannot be woken up.
• In team_race mode,, the uart that originally communicated normally loses connection suddenly, VTX will think that FC is faulty, and VTX will turn off RF at this time.

Yeah I get that, but it seems risky — normally the FC shouldn’t crash mid-flight and if the connection gets interrupted for some other reason you’ll lose video.

My team mates and I had a couple of times that the OSD stopped updating mid-flight. I suspect the VTX might turn off then with this change, which means I’d not only lose OSD, but also video.

• I think I've fixed the OSD stop updating issue in v1.1.0.
• This is only for team race.

[john-k3nnedy]

• I think I've fixed the OSD stop updating issue in v1.1.0.

I’ll keep an eye on it, but I was definitely running 1.1.0 or higher.

• This is only for team race.

I know, we’ll be at Mayhem!

[ligenxxxx]

• I think I've fixed the OSD stop updating issue in v1.1.0.

I’ll keep an eye on it, but I was definitely running 1.1.0 or higher.

• This is only for team race.

I know, we’ll be at Mayhem!

For people with different needs, I plan to add multiple options for team race, OFF/MODE1/MODE2.

• TEAM_RACE MODE1
  • Enable vtx paralyzed().
• TEAM_RACE MODE2
  • Disable vtx_paralyzed().
  • If VTX does not detect FC serial port during initialization, it will open RF.

[ligenxxxx]

#117 (comment)

• Beta FC FW is not a correct firmware, please do not use it.
• Obtaining FC paralyzed is temporarily blocked, and I haven't figured out how to obtain it correctly.

[lesharodin]

@ligenxxxx maybe you could make smth like this:
IF TEAM_RACE = OFF
PIT_MODE = default pitmode behaviour
IF TEAM_RACE = MODE1
PIT_MODE = 0MW
Then we can use pitmode + paralize from bf modes to power off vtx and paralize quad, without reading paralizy state from fc to vtx, beacuse it will be in pit and paralized anyway.