FrSky X9D Plus Taranis is incredible radio. But also can be intimidation when migrating from simpler radios. Great example is mixing multiple switches into 1 channel to pass flight mode to flight controller. Yes, you can do it, but it can be pain in the ass on a Mixer level. I’ve lost a lot of time trying to understand logic behind mixer weight and offset only to discover possibility to replace channel value, not add. And everything was simple again. So, here what I wanted, and what I did.
What I wanted
When I fly bigger FPV quadcopter, I want to use 7 different flight modes:
- Angle without Altitude Hold (no BARO),
- Horizon without Altitude Hold (no BARO),
- Acro/Rate without Altitude Hold,
- Angle with Altitude Hold (BARO),
- Horizon with Altitude Hold (BARO),
- Position Hold with Altitude Hold (BARO),
- Return To Home with Altitude Hold (BARO)
And I’ve figured out, that 3 switches should be used to enable all the flight modes: SC, SD and SG. SC toggles Angle/Horizon/Acro. SD switches PosHold and RTH (as well as BARO and overrides SC and SG). SG enables Altitude Hold but only when SC is in up or middle position. 3 switches, 7 modes. I could do it with 3 radio channels, but that would have few flaws: would use 3 channels instead of one, and would allow for mistakes like no BARO with POSHOLD. So, advanced mixes and logical switches that is.
|SC||SD||SG||Flight Mode||Altitude Hold||GPS||Logical Switch|
|–||Down||–||Angle||BARO||Return To Home||L5|
Solution in Taranis OpenTX requires 2 things: logical switches and mixer setting for CH5. For this example, Logical Switches goes as follows:
And mixer setting for CH5 is like that:
Each CH5 mixer entry uses Source MAX with weight 100 and is activated on Logical Switch (L1-L7). Channel output is determined by Offset value. Important setting is Multiplex: REPLACE, not ADD. And that is all. 7 flight modes, 3 switches, 1 radio channel. What is left to activate correct modes in Cleanflight based on CH5 (AUX1) value.