FrSKY Taranis - 5 modes and arming in iNav using 1 radio channel

Arming and modes on 1 channel, what the fuck!?

No word of a lie, the night before leaving for the Weston Park Model Air Show, the idea got in my head that having the arming switch on it's own channel is a complete waste of a channel. This is 2018, why have only 1 function on a 1 channel; after-all, you don't care about flight modes if the model is not armed! This kept swirling around in my head all night, so much so that I had to get up early and try to figure it out, to the point where I left my house 20 minutes late, oops! Still, I worked it out and confirmed it today on my Taranis and iNav setup for my S800 builds.

The idea is that all the time the model is disarmed, no flight mode preference is sent to iNav, and it uses a default flight mode (manual). This does not effect the switches you use for arming or flight modes, just that instead of using Ch5 for arming and Ch6 for modes, for example, Ch5 would do both. As soon as you arm, iNav not only knows that you're armed, but also which flight mode you want to be using. So simple, and frees up a channel. It's pretty much a combination of my Throttle Cut with Safety Arming and 5 Modes Using 1 Channel tutorials, with an extra special function added.

Step 1 - The arming mechanism

As I mentioned earlier, this is the same as my Throttle Cut with Safety Arming tutorial, but as a quick recap...

L01 | a<x | Thr | -98 | L02 | OR | L01 | L02 | SF↑ | 0.0 | 0.5 SF1 | L02 | Play Track | Armed SF2 | !L02 | Play Track | Disarmed

Next we add the modes stuff, but we will add another Special Function for the arming later

Step 2 - Adding the flight modes

This is fairly similar to the 5 Modes Using 1 Channel tutorial, however the output to the channels in the Special functions screen is different.

L04 | a>x | SA | 50 L05 | a=x | SA | 0 L06 | a<x | SA | -50 | SB↑ L07 | a<x | SA | -50 | SB- L08 | a<x | SA | -50 | SB↓ FM0 | Manual FM1 | Horizon | L05 FM2 | Alt Hold | L06 FM3 | Loiter | L07 FM4 | RTH | L08

This is where things change a little from the previous tutorial.

SF4 | FM0 | Override CH5 | -33 | ✔ SF5 | FM0 | Play Track | fm_manul | x1 SF6 | FM1 | Override CH5 | 0 | ✔ SF7 | FM1 | Play Track | fm_horiz | x1 SF8 | FM2 | Override CH5 | 33 | ✔ SF9 | FM2 | Play Track | fm_ahold | x1 SF10 | FM3 | Override CH5 | 66 | ✔ SF11 | FM3 | Play Track | fm_loitr | x1 SF12 | FM4 | Override CH5 | 100 | ✔ SF13 | FM4 | Play Track | fm_RTH | x1

Step 3 - Final settings

SF14 | !L02 | Override CH5 | -100 | ✔

That's everything set in the Taranis, now for the iNav configuration.

iNav Modes setup screen, showing the positions for the flight mode and arming switching.

I've re-arranged the modes on the screen to make it easier to see how it works and how you set it up. The first thing you want to do is make sure that Arm, Manual, Horizon (or Angle if you prefer), Nav Althold, Nav Poshold, and Nav RTH are all set to use CH 5. On the Taranis, arm the model and set the flight mode to Manual. Set the slider on the Arm mode so that it starts just before the position marker and ends at the far right hand side. The Manual mode should start on the far left side and end just after the position marker. This setting means that the model will be armed for all flight modes, and when the model is disarmed it will be in manual mode. The rest of the flight mods are set up as normal. Below I have added some images to help show the position markers for the different modes.

Image showing the iNav modes screen in the disarmed state.
Disarmed
Image showing the iNav modes screen in manual mode.
Manual
Image showing the iNav modes screen in horizon mode.
Horizon
Image showing the iNav modes screen in altitude hold mode.
Altitude Hold
Image showing the iNav modes screen in loiter mode.
Loiter
Image showing the iNav modes screen in return to home mode.
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