Mixes Scripts¶

Danger

Don't use Lua Mixes Scripts for controlling any aspect of your model that could cause a crash if the script stops executing!

Purpose¶

Mixes Scripts take one or more values as inputs, do some processing in Lua code, and output one or more values. Each model can have several Mixes Scripts associated with it, and these scripts are run periodically. They behave similarly to standard EdgeTX mixers, but at the same time they provide a much more flexible and powerful tool.

Typical use cases:

replacement for complex mixes that are not critical to model function
complex processing of inputs and reaction to their current state and/or their history
filtering of telemetry values

Execution & Lifetime¶

Mixes script is loded when model is selected.

Script executes until

it misbehaves (e.g. run-time error or low memory)
One-time Script is running. When One-time script finishes execution, Wigdet Script resumes execution.

Warning

Limitations¶

cannot update LCD screen or perform user input.
should not exceed allowed run-time/ number of instructions.
custom scripts are run with less priority than built-in mixes. Their execution period is around 30ms and is not guaranteed!

Warning

If the script output is used as a mixer source , and the script is killed for whatever reason, then the whole mixer line is disabled!

Info

Mixes Scripts should be as short as possible, to avoid delays. It is also important to keep in mind that other loaded Telemetry and Function scripts can add to the response time, or worse: hang the system!

Info

By default, the necessary compile time option LUA_MIXER to use Mixes Scripts is enabled for all radio targets from EdgeTX v2.11 onwards.

File Location¶

Mixes scripts are located on SD card in folder /SCRIPTS/MIXES/

Warning

File name length (without extension) must be 6 characters or less

Interface¶

Every Mixes Script must include a return statement at the end, defining its interface to EdgeTX. This statement returns a table with the following fields:

table item	type	required
run	function	yes

This function is called periodicaly when script is running.

Parameters
Variables matching those used in input table

Return values
Variables matching those used in output table

table item	type	required
init	function	no

This function is called once when Mixes Script is loaded and executed for the first time

Parameters
none

Return values
none

table item	type	required
input	table	yes

The input table defines what values are available as input(s) to custom scripts.

There are two forms of input table entries

SOURCE

{ "<name>", SOURCE }

SOURCE inputs provide the current value of a selected EdgeTX variable. The source must be selected by the user when the script is configured. Source can be any value that EdgeTX knows about (inputs, channels, telemetry values, switches, custom functions etc.).
Note: the typical input range is -1024 thru +1024. Simply divide the input value by 10.24 to convert to a percentage from -100% to +100%.

VALUE

{ "<name>", VALUE, <min>, <max>, <default> }

VALUE inputs provide a constant value that is set by the user when the script is configured.

name - maximum length of 8 characters
min - minimum value of -128
max - maximum value of 127
default - must be within the valid range specified
Maximum of 6 inputs per script

table item	type	required
output	table	yes

The output table defines only name(s), as the actual values are returned by the script's run function.

{ "<name1>", "<name2>" }

Info

Above names are only visible as source values on the radio screen when the script is running. If the model is edited in Companion, then the values show as LUA1a and LUA1b etc.

Examples¶

Example of a Mixes Script using a SOURCE input and a VALUE input together.

local my_input =
  {
    { "Strength", SOURCE},           -- user selects source (typically slider or knob)
    { "Interval", VALUE, 0, 100, 0 } -- interval value, default = 0.
  }

local my_output = { "Val1", "Val2" }

local function my_init()
  -- Called once when the script is loaded
end

local function my_run(Strength, Interval) -- Must match input table
  local v1, v2
  -- Called periodically
  return v1, v2                        -- Must match output table
end

return { input = my_input, output = my_output, run = my_run, init = my_init }

Example where Lua mix script is used to drive ailerons in some clever way, but control falls back to the standard aileron mix if script is killed. Second mixer line replaces the first one when the script is alive:

CH1  [I4]Ail Weight(+100%)
  := LUA4b Weight(+100%)