Question about FrSky output mapping

In case you do not know something or you are not sure, here is the right place for your question.
azaz44
Posts: 288
Joined: Thu 12. Jul 2018 17:51:47

JoergZ wrote:but your pics are showing subtrims not zero
Yes. This is what I have to set to see zeros on this screen:

Image
ZeXx86
Site Admin
Posts: 12834
Joined: Mon 29. Apr 2013 16:06:44
Contact:

Spirit units are doing automatic channel centering each powerup.
So subtrims will not play a role.

But it is only important to have default channel layout on Spirit and radio configured to TAER layout.
Then it all will work well as with Futaba out of the box. No trimming is needed.
Spirit System developer
azaz44
Posts: 288
Joined: Thu 12. Jul 2018 17:51:47

ZeXx86 wrote:Spirit units are doing automatic channel centering each powerup.
So subtrims will not play a role.

But it is only important to have default channel layout on Spirit and radio configured to TAER layout.
Then it all will work well as with Futaba out of the box. No trimming is needed.
They do centering at power on for cyclics and rudder, but for pitch I think? I need to offset pitch too.
Also gyro gain.

As for channels, I use TAER in transmitters, but in Spirit order becomes different:

Image

This is true for both OpenTX and Ethos. Should it show TAER in this window in Spirit?
(I think I would then need to use ETAR in radio)

but I also wonder why would order matter if we have "mapping" in Spirit.
Although I could remap all my 7 Spirits if this would improve things.
Mattes61
Posts: 628
Joined: Wed 21. Dec 2016 15:13:38
Location: Germany

Hello,
I have the same problems with centering, some channels are at mid "0" but some are two or threee off - And yes I have it also compensated with subtrim, there is no other chance..If I do not change the Middlepoint the max and min are asymmetrical - at the moment I see no other chance to set the mid to zero -
Here the auto-zero Mid point does not work reliable -
Maybe Tomas can change that easy ?

Regards
Matthias
franz88
Posts: 338
Joined: Sun 08. Jan 2023 14:32:43

If you use subtrim spirit is it as if it receives an input ?
For example if you use subtrim elevator it will always move up elevator etc.
Is exact zex ?
ZeXx86
Site Admin
Posts: 12834
Joined: Mon 29. Apr 2013 16:06:44
Contact:

Please never use subtrims for aileron, elevator, rudder. It will be reseted to zero during next poewrup - automatic channel calibration.

You should leave channel mapping at default at both radio and spirit. Only change mapping layout and it will work immediately.
Spirit System developer
Mattes61
Posts: 628
Joined: Wed 21. Dec 2016 15:13:38
Location: Germany

Hello Tomas,
please tell me the solution of getting all channels to "0" as azaz44 said pitch and Gyro are not at "0" by start up -
Why are these two channels not at zero, can you please explain it, there must be an difference to the other channels...
I don't touch the channel mapping as additional information -

Thanks for the tipps - and in the Spirit Settings by doing "false subtrim" the middle stays always "0" and not a flickering value...

Regards
Matthias
jjuk
Posts: 305
Joined: Thu 05. Oct 2017 20:06:35

Here's my setup for a spirit2



Image

And a different model:

Image


Note the gyro channel requires +-96 not 83 as per other channels.
Mattes61
Posts: 628
Joined: Wed 21. Dec 2016 15:13:38
Location: Germany

Hello,
your PWM-Center is at 1520 us, but by default this is at 1500us -
What setting is correct 1500 or 1520 us - To get a proper "0" you can set it with PWM-Center or by center/subtrim -
Apparently the automatic adjustment to "0" does not work here, why ?

Please Tomas can you something say about that ?

Regards
Matthias
azaz44
Posts: 288
Joined: Thu 12. Jul 2018 17:51:47

I tell you what, I spent hours on discovering how it works. This is very tricky and I don't fully understand why. Here are my results.

I tested all of this on Ethos. Probably it is same for OpenTX but I'm not 100% sure.

Also, this is with Spirit GT and Archer RS, and FrSky x20s radio.
I have to retest if it will be same for other models I have.
But so far my experience is that other FBL units and other receivers don't make a difference.

Also, I really hope that "Diagnostics" page in Spirit shows correct results, because I fully relied on this.
It would be great to see numbers with fractions there (like 100.0%), this would help.

AIL, ELE, RUD

These channels center themselves when powering on Spirit, and this is already reflected on the "Diagnostics" page. What this means, is: if you change centering (and you see non-zero values on "Diagnostics" page), after you restart Spirit, you will see zeros again.

So PWM / center / subtrim doesn't matter for them. But I think they should all be set to same PWM center (for pitch - see later).

My setup that works:

Min: -82.9
Max: +82.9
Center/Subtrim: 0
PWM Center: 1500

Pitch

It seems that "Pitch" also centers itself at the startup of the radio, but not from its own channel (#6) which is of course not possible. It rather somehow uses combination of RUD, AIL and ELE to center itself. If you would start FBL with RUD or AIL or ELE non zero, pitch centering will be affected.

But what is weird, it offsets this by some value.
So to get "0" pitch in Diagnostics, when radio sends "0", I have to offset PWM center for Pitch (comparing to RUD, ELE, AIL).

This works for me:

Min: -82.9
Max: +82.9
Center/Subtrim: 0
PWM Center: 1507

Why? I don't know, but it works.

Gyro Gain (#5)

Here I can't get perfect setup, where each % value sent by radio would match same value on "Diagnostics" page. But this is not very needed for this channel. This works well:

Min: -95.2
Max: +95.2
Center/Subtrim: 0
PWM Center: 1518

Why this channel needs such big range comparing to other - no idea.

Channels 8-16 for custom functions

If you use custom functions, then this is what I found workin:

Min: -82.5
Max: +82.5
Center/Subtrim: 0
PWM Center: 1518

Best test is using "Pirouette Consistency", because with range 50-250 it spans over 201 values, just like radio with -100..+100 %.
With this setup I get exact match, so -100% = PC 50, 0% = PC 150, +100% = PC 250 and changing value in radio by 1% changes pirouette consistency by 1 across the whole range.

This part is important for me, because I control some values with channels, like "Cyclic rotation rate" and I really want to be sure that if I set my models same, to have - for example - cyclic rotation of 13, I get same thing in every model. So I'm very happy I found some consistency here and I hope it works for all models. Changing PWM center was key here.

Throttle

Here I don't know. I didn't want to mess with this one, to not recalibrate ESCs.
But maybe I check one day, as it would be good to have a proven set of numbers, which can be copied anytime you setup a heli.
Post Reply