Update OSD throttle options

[MrD-RC]

Fixes #8801

Pre-INAV 3.0 there were two working throttle display elements. A PR in 2.7 (#6510) made a change that meant both OSD throttle elements showed the same data. This is pretty pointless. The previous method allowed the display of the throttle in a non-scaled view, which made selecting navigational throttles easier. This PR allows the pilot to see scaled throttle, unscaled, or both. Both throttles work for manual and auto throttle.

Configurator iNavFlight/inav-configurator#1725

[breadoven]

getThrottleIdleValue should be assigned to a const

[MrD-RC]

True. No point in multiple calls.

[breadoven]

1000 surely ?

[tiriad]

thr = (thr - PWM_RANGE_MIN) * 100 / (PWM_RANGE_MAX - PWM_RANGE_MIN);

[MrD-RC]

@breadoven Yes, should be -1000, typo.

@tiriad Actually, this would be better, as it is based on PWM_RANGE_MIN and PWM_RANGE_MAX.

[tiriad]

Yes, I only suggested it to follow the style of other variables and the code prior to the modification assuming it was correct.

inav/src/main/io/osd.c

Line 879 in 5510259

thr = (constrain(rcCommand[THROTTLE], PWM_RANGE_MIN, PWM_RANGE_MAX) - PWM_RANGE_MIN) * 100 / (PWM_RANGE_MAX - PWM_RANGE_MIN);

[tiriad]

what do you think if you add in addition a field with the raw value rcCommand[THROTTLE] for the purpose of tunning?

[MrD-RC]

That is effectively what the unscaled throttle percentage is. I think showing the PWM value would be a step backwards. Plus, that could probably be done now using logic conditions and a Gvar.

[tiriad]

I have already managed to obtain the PWM value. A curious case here is that this value is already a % in the PWM range.

inav/src/main/programming/logic_condition.c

Lines 690 to 692 in b355551

	case LOGIC_CONDITION_OPERAND_FLIGHT_TROTTLE_POS: // %
	return (constrain(rcCommand[THROTTLE], PWM_RANGE_MIN, PWM_RANGE_MAX) - PWM_RANGE_MIN) * 100 / (PWM_RANGE_MAX - PWM_RANGE_MIN);
	break;

[MrD-RC]

It is also not scaled.

[MrD-RC]

I've got this to a stage where it's as good as it can be without the throttle getting a complete overhaul. The problem is the scaling. This should really only happen before output (to the motors or the OSD if a scaled output is requested). The problem is it happens in places like navigation. This is not just a mess for the OSD. But it means that other areas work differently too. For example, outputting 'rcCommand[THROTTLE]' from logic_condition.c will give a different result to outputting 'rcCommand[THROTTLE]' from mixer.c. mixer.c is where the throttle output is calculated for the OSD. At that point, it has already been scaled.

In this image. The throttle on the stick is central (1508us). The outputs in configurator and the 45% throttle on the OSD should be the same value.

For this PR, I've had to compromise. The scaled throttle OSD element is using the same code as before. I don't believe this is necessarily correct, as it is different to the value shown in configurator for the motor output. The unscaled output is correct. But due to rcCommand[THROTTLE] already being scaled at this point, the auto-throttle will have to show the scaled value currently. I tried reversing the scale. But the result was not correct. I think it would be better to remove the scaling, until output. Only then will we get a properly consistent and clean throttle setup.

Either way. It's better than what's currently in INAV. As both throttle OSD elements are identical. The only thing I'm not sure about is the *. This was to differentiate between the two types of throttle. But I think it could be better. Maybe 2 throttle symbols instead of the *. But I'm open to suggestions. Ideally ones that don't need a new font character.