Taranis: Change S1 & S2 to Switches - RC Groups
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Nov 12, 2016, 08:31 AM
Pompano Hill Flyers
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Taranis: Change S1 & S2 to Switches

If 3-position switches (short or long) are wired in parallel with the S1 and S2 potentiometers ("pots"), the pots are left in their center positions (very important), insulated, and stored inside the radio, and the switches are installed in their places, the following six additional switch functions will be available:

S1↑ S1− S1↓ S2↑ S2− S2↓ (Of course these designations won't show up on your radio screen or in Companion but they can be useful in your programming notes.)

Decoding S1↑ and S1↓ with Logical Switches:
L1	a~x S1  100 ---- 0.0 0.0 L1 = S1↑ 
L2	a~x S1 -100 ---- 0.0 0.0 L2 = S1↓
These two Logical Switches may be reversed, depending
upon which way the 3-position switch is installed in your radio.
If S1− represents a default setting then it might not need to be specifically decoded, otherwise it can be decoded with a third Logical Switch:
L3	AND !L1 !L2 ---- 0.0 0.0 L3 = S1−
The code for S2 is similar:
L4	a~x S2  100 ---- 0.0 0.0 L4 = S2↑ 
L5	a~x S2 -100 ---- 0.0 0.0 L5 = S2↓
L6	AND !L4 !L5 ---- 0.0 0.0 L6 = S2−
To wire a 3-position switch in parallel with a pot, use short insulated jumper wires to connect the top terminal of the pot to the top terminal of the switch, the center terminal of the pot to the center terminal of the switch, and the bottom terminal of the pot to the bottom terminal of the switch. Remember that the pot has to stay connected even though it won't be accessible, and it has to be set to the center detent position.

If you want to reverse the modification later it won't be necessary to disconnect or remove the switch. Just set it to its center position, insulate it, store it away inside the radio, and put the pot back where it used to be. Remember that in either case the control that's not being used must remain set to its center position.

Last edited by Miami Mike; Nov 14, 2016 at 12:17 PM.
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Nov 13, 2016, 05:16 PM
Pompano Hill Flyers
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This is an example where decoding S1− is not necessary.

I'm using switch S1 for aileron triple rates, and it happens that I can select all three rates using only two logical switches:
L9  a~x S1  100 ---- 0.0 0.0 (L9 = S1↑) 
L10 a~x S1 -100 ---- 0.0 0.0 (L10 = S1↓)
On my Inputs page I have three aileron rates designated AileHigh, AileMid, and AileLow, but AileMid is the last line and functions as a "catchall" so that the aileron stick is guaranteed to work even if none of the lines above it are active.

    Ail Weight(+90%) Switch(L9) [AileHigh]
    Ail Weight(+60%) Switch(L10) [AileLow]
    Ail Weight(+75%) [AileMid]
On the Inputs page, OpenTX uses the first line that's true for each channel and ignores what's below it.
Last edited by Miami Mike; Nov 14, 2016 at 12:22 PM.
Feb 09, 2018, 07:37 AM
Pompano Hill Flyers
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Update, February 6, 2018

Here's the logical switch decoding setup I finally settled upon and use today:

L9 S1 > 66
L10 S1 < -66
L11 S2 > 66
L12 S2 < -66
All of the radio mods and programming setups in my blog are developed with, and designed for, the FrSky Taranis Plus using OpenTX version 2.1.9. If you've adapted any of them to other radios or later OpenTX versions, or found a better way to do what I've described here, please feel free to describe your version or link to it in the comment section below the relevant post.

Latest blog entry: Shepard Tone Vario for OpenTX

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