Mixing it!
Mixers in Ethos
Introduction
Ethos offers a comprehensive selection of mixers. In this article, I'll explain how they work, what they're used for, and the various options. I'll focus on the glider mixers, however all the mixers work in a similar way.
Mixer categories
The mixers fall roughly into four broad categories:
- Primary mixers
- These mixers correspond to the main flight controls, and comprise Ailerons, Elevators and Rudders. The input is the stick. The outputs are the servo channels. There are settings for rates, and the trim value is included in the output.
- Secondary mixers
- Mixers in this group have names in the form {stick/slider/knob}=>{channel}. For example, Ail=>Rud mixes the aileron stick to the rudder channel. Other mixers in this group include Ail=>Flaps, Rud=>Ail, Flaps=>Ele and Ele=>Camber.
- Tertiary mixers
- Examples include Butterfly and Camber. With these mixers, you choose the input (stick, lever or knob). Trims are not included in the outputs.
- Special mixes
- These comprise Offset, VAR, FreeMix and Trim mixes.
Mixer parameters
The parameters used by the various mixers are shown in the table below:
| Parameter | Description |
| Input/source | The stick, knob, switch etc. providing the input value to the mixer. |
| Active condition | A condition (for example a physical or logical switch). For the mix to be enabled, the condition must be true. The default is 'always on'. |
| Flight modes | List of flight modes. For the mix to be enabled, the active flight mode must be one of those listed. The default is 'all flight modes'. |
| Curve | A curve (for example deadband or expo) which is applied to the input. The curve is applied before the weight. With some mixes, you can specify more than one curve, each with a condition. If more than one condition is true, the curve higher in the list wins. |
| Weight | A percentage to multiply the input value (after any curve is applied). The value may be a constant, or it may be linked to a control or channel. A negative value reverses the mix.
With some mixes, the same weight is applied to all the outputs. With other mixers, a separate weight is specified for each output. |
| Offset | A constant value which is added to the output (similar effect to a trim). In some mixes, the offset may be linked to a source/channel. |
| Slow up/down | Time in seconds for output to follow input. |
| Differential | Differential reduces the effect of the input, in one direction only. Applies to Ailerons and Elevators mixers only. The amount may can be derived from a separate source, providing a mechanism for in flight adjustment. |
| Channels count | The number of destination channels. |
| Outputs | Channel numbers of the destination channels. |
| Reverse | Reverses the sign of the output value. |
| Throttle Cut | [TBC] Applies to Throttle mixer only. |
| Throttle Hold | Sends the throttle to a user defined value. Applies to Throttle mixer only. |
| Low position trim | [TBC] Applies to Throttle mixer only. |
Mixer reference
Below is a list of the available sailplane mixers, colour coded by category.
Key:
| bold | Parameter may be derived from a stick, logical switch or other source |
| value | Multiple values, each with condition |
| output | Multiple outputs |
Ailerons
Active condition
Flight modes
Curve
Weight
Differential
Channels count
Output
Mixes the aileron stick to one or more channels, in alternate directions, for roll control. The same weight is applied to all outputs. The trim value is included in the outputs.
For wings with four or six control surfaces, define multiple Aileron mixes, one per pair of surfaces.
This mixer is functionally identical to the Ail=>Flap mix - only the default output channels differ.
Elevators
Active condition
Flight modes
Curve
Weight
Differential
Channels count
Output
This mix is designed for the elevator function. The input is the elevator stick. The default output is the elevator channel(s). The trim value is included in the output.
Rudders
Active condition
Flight modes
Curve
Weight
Channels count
Output
This mix is designed for the rudder function. The input is the rudder stick. The default output is the rudder channel(s). The trim value is included in the output.
Ail=>Rud
Active condition
Flight modes
Curve
Channels count
Weight
Output
Aileron to rudder mix. The input is the aileron stick. The default output is the rudder channel(s).
Ail=>Flaps
Active condition
Flight modes
Curve
Weight
Differential
Channels count
Output
This mix is identical to the Ailerons mix except that the default outputs are the flap channels.
Rud=>Ail
Active condition
Flight modes
Curve
Channels count
Weight
Output
A rudder to aileron mix. The input is the rudder stick. The default output is the aileron channels.
Flaps=>Ele
Active condition
Flight modes
Input
Curve
Channels count
Weight
Output
This mix is useful for flap/camber/crow compensation, where a dedicated compensation curve is required. You choose the input. The default output is the elevator channel.
Note that there is no Slow option. If you have Slow enabled on flaps, then to obtain matching slow compensation, use one of the flap channels as the input to this mix (instead of the flap control).
Ele=>Camber
Active condition
Flight modes
Input
Curve
Channels count
Weight
Output
Also known as 'snapflap'. You choose the input (normally the elevator stick). The outputs will be the flap and optionally the aileron channels. Each output has an independently adjustable weight.
Butterfly
Active condition
Flight modes
Input
Curve
Channels count
Weight
Output
Note: applies to Ethos v1.4.9 and later. This mix is used for crow brakes. The input will normally the throttle stick or a lever. Ethos defines a read-only input curve which maps stick values to crow values in the range 0% - 100%. This curve can be over-ridden with your own curve, for example to include some deadband at the zero end of stick travel. The outputs will be the flap and aileron channels, and (optionally) the elevator channel. Output weights are independently adjustable.
Camber
Active condition
Flight modes
Input
Curve
Channels count
Weight
Output
This mix has five outputs by default. Use typically to control the camber on ailerons and flaps. The fifth output can be used for elevator compensation where a dedicated curve is not required.
Flaps
Active condition
Flight modes
Input
Curve
Slow Up
Slow Down
Channels count
Weight
Output
Flap mix. By default this mix has two outputs, for the flap channels. A third output could added for simple elevator compensation where a dedicated curve is not required (if a dedicated curve is required, then an additional Flaps=>Ele mix should be used).
Throttle
Input
Throttle Cut
Throttle Hold
Flight modes
Curve
Weight
Low position trim
Channels count
Output
This mix is for motor control.
Offset
Active condition
Flight modes
Offset
Channels count
Output
Applies an offset to one or more channels. This mix is useful in models with flaps with asymmetrical up/down movement.
Var
Weight
Output
The VAR mix assigns a value to a channel. The value is supplied through the weight parameter. The weight may be a constant, or supplied through a source like a slider or channel.
Multiple weights may be specified, each associated with a condition. In the event of a conflict, the condition highest in the list wins.
VAR mixers provide a convenient way to specify configuration values which might be routinely changed, for example the weights of key mixers.
FreeMix
Active condition
Flight modes
Source
Function type
Curve
Offset
Weight up
Weight down
Slow up
Slow down
Channels Count
Reverse
Output
A general purpose mix with flexible options. Use it to add functionality lacking in the standard mixers. An example is in-flight mix adjusters.
An entire setup can be created using free mixes, much in the style of OpenTX.
Trim
Active condition
Flight modes
Source for Up
Source for Down
Trim Mode
Extended Trims
Channels Count
Output
The Trim mix makes a control behave like a trim button. While the control is active, the output changes incrementally at set time intervals (like a regular trim). There are separate inputs for up and down, however you will normally set these to the same physical control.