SR/SxR Switchology in OpenTX

 There was a question asked about how to set up Hover and Knife Edge modes in OpenTX for the FrSky Stabilized receivers.

As I've mentioned in the past, the mode selection table, which is based on Ch10 and Ch11, is absolutely horrid for these receivers, which is why I generally just point people at Quick Mode, which not only is easier to setup but only costs you two mostly useless modes, Hover (which works, ish) and Knife Edge (which only goes one way and is thus kind of useless)

This is a simpler setup in terms of logic switches that the push-button example I did previously in ETHOS, but as you can see, the programming is actually a little more complex since there isn't a direct replacement for a VAR mix in OpenTX (in so far as a VAR Mix can't fully replace a GVAR, a GVAR can't fully replace a VAR mix)

Here is what is in my opinion a sane switch setup for OpenTX

I'm using the following Switchology, this was setup on my TX16S

SB is the main Stab Mode switch. Up is Stab off, Mid is Stab only, Down is self-level/hover/KE

SC is the self-level mode switch. Up is KE, Down is Hover, mid is regular Self-Level

I used 3 LS's to do this.

L01 is AND SBdn SCup (KE)
L02 is AND SBdn SCdn (Hover)
L03 is AND SBdn !SCup (!KE)

Ch10 has the following mixes:

1. Source:MAX Weight 100%
2. Source:MAX Weight -100% Switch:L01 Multi:Replace
3. Source:MAX Weight 0% Switch:SBup Multi:Replace

Ch11 has the following mixes:

1. Source:MAX Weight 0%
2. Source:MAX Weight 100% Switch:L03 Multi:Replace
3. Source:MAX Weight -100% Switch:L02 Multi:Replace

For a Panic Mode, SH can be used as the input for a 4th Replace mix for both CH10 and 11 (force both to +100 to engage Self-Level, must be the last mix to override the others)

I don't fully like this, if only because it doesn't quite have the default mode I'd like. It defaults to stabilization on, and I'd prefer Stabilization off or self-level as the default. That would require even more complex mixing though, because I really am leveraging mixer priority to simplify the number of needed mixer lines (something I didn't do in ETHOS because creating a single value line in a VAR mix is way quicker than setting up a mixer)

Getting Fancy with the SR's and ETHOS

 Someone asked about how to handle the bad logic necessary to access the Hover and Knife Edge modes on the SxR and SR series. These modes are available if you are NOT using Quick Mode on the receiver. Personally, I recommend Quick Mode. 

They wanted stab modes on SC and push button access to Hover and Knife edge modes using the rear buttons. This is what I came up with:

OK, this takes 6 Logic switches and 2 VAR mixes.

First off are two Sticky LS's, to turn Hover and Knife Edge on and off.

They're both setup the same way, note I have SCmid assigned to rates stab and SCup to Self-level in this example (slightly different than the provided example, but it gives self-level if you accidentally disable hover or knife edge modes

Sticky SIdown SIdown Act:SCup
Sticky SJdown SJdown Act:SCup

Name one Hover and the other Knife Edge

Next is one which Determines if either of these are active

Name it 'Special Act'

LS:'Hover' XOR LS:'Knife Edge

Next are two to ensure you can't flip accidentally between Hover and Knife Edge

Name the first 'Hover Act'

LS:'Hover' AND !LS:'Knife Edge'

Name the second 'KE Act'

LS:'Knife Edge' AND !LS:'Hover'


These will be active only when one of those two special modes is engaged, but not the other.

Finally there's the regular Self-level mode

Name it 'Self-Level'

SCup AND !LS:'Special Act'

This one will be true when the other two aren't and SC is up.

Now we use two VAR mixes.

The CH10 Mix has a default weight of 0
The next weight is triggered on SCMid and is 100
The next is triggered on LS: 'Self-Level' and is 100
The next is triggered on LS:'Hover Act' and is 100
The last is triggered on LS:'KE Act' and is -100
Output is Ch10

The CH11 Mix has a default weight of 0
The next weight is triggered on LS:'Self-Level' and is 100
The last weight is triggered on LS:'Hover Act' and is -100

You could simplify the Ch10 VAR mix with an additional Logic Switch, but it becomes harder to compare to the logic table in the SRx/SxR docs. If you want to drop self-level and have rates stab on with SCup and no regular self-level, delete the self-level lines on both mixes (and the Self-Level LS) and change SCmid to SCup on Ch10.

Programming ETHOS for the Archer SR Receivers for a conventional plane

I'll be covering how to setup the radio side of setting up the SR series receivers here. I'll go over receiver setup in a separate post. I'll also address Delta and V-Tail mixing another time.

First off, a couple things to cover on the receiver side because they significantly impact how you are going to program the radio.

1. Mixing. The SR series do internal delta and v-tail mixing. They DO NOT mix dual channel ailerons or dual channel elevators, although they can support both functions. You need to program delta and v-tail setups as conventional 4ch models on the radio, but dual-channel ailerons and elevators must be programmed at the radio.

2. USE QUICK MODE. the Archer SR series default to Quick Mode. Quick Mode doesn't support Hover Mode or Knife-Edge Mode. You probably don't need Hover Mode and Knife Edge mode only does one orientation and it's useless as a result. Plus the mode switching logic for these is nutty and requires a lot of in depth switchology to get usable switch setups from the crazy bad mode table. I'll only address Quick Mode in this post.

This post is going to cover how I program a standard aircraft with an Archer SR receiver. The dual elevators logic will be the same as dual ailerons.

First off we are going to create a new Model, and set it up as a standard 4 channel aircraft. Select 2 ailerons if you have/want dual channel ailerons.

The second step is to ensure the channels are mapped properly. If your default Channel Mapping is not AETR, you will need to remap the 4 basic channels

Make sure the channels are mapped as follows, by going to the Model->Mixer page and editing each mix and changing the Output channels for each mix if they don't match the following.

Ailerons->Ch1
Elevator->Ch2
Throttle->Ch3
Rudder ->Ch4

*Note if you are doing dual-channel ailerons, the right aileron must be on Ch5. Right Elevator must be on Ch6 if doing dual-channel elevators. These channels are hard coded at the receiver for stabilization.

How I do this is as follows. Note I have traditionally used TAER (JR/Spektrum) mapping as my default.

So I do this.

Edit Elevators mix. 
Set output channel from Ch3 to Ch7. Swap configs, accept channel name change. This clears Ch3 to be re-assigned without losing a channel name.
Edit Throttle Mix. 
Set output channel from Ch1 to Ch3. Swap configs, accept channel name change.
Edit Ailerons Mix.
Set output channel from Ch2 to Ch1. Swap configs, accept channel name change.
Edit Elevators mix. 
Set output channel from Ch7 to Ch2. Swap configs, accept channel name change.


Next, edit the Throttle mix, enable Throttle Cut, set the active condition to your preferred 'throttle disabled' setup, I use SFup on the X20. This is important later.

Now back out to the Mixer page

Hit the + to add a mix, select Free Mix, select Last Position
Change the name to Gain
Set the Source to Pot1 (or your preferred analog gain input)
Set the offset to 50%
Set the Weight Up to 50%
Set the Weight Down to 50%
Set the output Channel to Ch9, accept the name change offered

Now back out to the Mixer page

Hit the + to add a mix, select Free Mix, select Last Position
Change the name to Stab Mode
Set the Source to SB, or your preferred 3-position switch to control Stabilizer Modes
Set the output Channel to Ch10, accept the name change offered

Now back out to the Mixer page

Hit the + to add a mix, select Free Mix, select Last Position
Change the name to Panic
Set the Source to SH (or your preferred momentary for emergency self-level)
Set the Active Condition to SFdown, or the opposite position of the switch used for throttle hold (ie this mix will only be active if the throttle is active)
Set the output Channel to Ch12, accept the name change offered

Now back out to the Mixer page

Hit the + to add a mix, select Free Mix, select Last Position
Change the name to Self-Check
Set the Source to SA (or your preferred and otherwise unused 3-pos switch for self-check. this MUST be a 3-pos)
Set the Active Condition to SFup, the same condition Throttle Hold is active in (this will only be active if the throttle is disabled, to prevent self-check in the air)
Set the output Channel to Ch12, decline the name change if offered.

Now go to System->Hardware->Switches Settings and set the Switch middle detect delay to 0ms or Self-Check won't work.

For flaps, be sure to select your flaps configuration when creating the new model. Note that if your flaps are going to be on ch5 and/or 6, there is receiver configuration required,