VTX Disarm Delay

[ugglguggl]

Current Behavior

Digital FPV systems such as DJI O4 enter low-power mode immediately (and stop recording) upon receiving the disarmed status via MSP. However, INAV's post-flight statistics screen is only rendered in the OSD after disarm. Thus the stats screen is not recorded automatically.

Desired Behavior

A short, configurable delay (e.g. 1000–3000 ms) between the actual disarm event and the MSP disarm notification would allow the post-flight statistics to be fully displayed and recorded before the air unit enters low-power mode.

Suggested Solution

New CLI parameter: msp_disarm_delay
Type: uint16_t, unit: milliseconds
Range: 0 – 30000 ms
Default: 0 (current behavior, no delay)
The FC disarms immediately as normal (motors stop, all safety logic unchanged). Only the MSP status message reporting the disarmed state to the VTX/air unit is delayed.

Who does this impact? Who is this for?

all users using digital VTX systems relying on MSP arming state for power management, like DJI O4 in my case

Additional context

n/a

[sensei-hacker]

Related:

#10462

#9688

I can certainly see why someone would want their DVR to continue recording for a few seconds after disarm.
There is certainly an argument to be made that the MSP shouldn't lie and say that the vehicle/motors are armed when they actually aren't though.

Really the RIGHT solution is for the DVR to keep recording for a few seconds after disarm. In other words, it's a DJI issue, which DJI could easily fix, rather than having INAV send false data to trick DJI into sucking less.

On the other hand, this is something DJI customers have been asking for for several years and doesn't seem DJI has cares - they may have no intention of ever improving their product. It may be that the only way DJI users will ever get sane behavior is for INAV to trick the DJI vtx into thinking the vehicle is still armed.