LUA Reference Guide
2.8
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Lua data sharing across scripts

Overview:

OpenTX considers all function, mix, and telemetry scripts to be 'permanent' scripts that share the same runtime environment. They are typically loaded at power up or when a new model is selected. However, they are also reinitialized when a script is added or removed during model editing.

Lua scoping rules:

Any variable or function not declared local is implicitly global. Care must be taken to avoid unintentional global declarations, and ensure that the globals you intentionally declare have unique names to avoid conflicts with scripts written by others.

Example:

This example consists of three scripts
  • count-dn.lua - this is a mix script than can be run stand alone to announce time remaining based on a user-defined switch and duration. It updates two global variables (gCountUp and gCountDown). It also creates output values (ctup and ctdn) which are for demonstration purposes only.
  • count-up.lua - this is an optional function script which will do count up announcements based on harded coded values.
  • shocount.lua - this is an optional telemetry script which simply shows the current values of the gCountUp and gCountDown variables.

Installation:

  • count-dn.lua
    • copy to /SCRIPTS/MIXES
    • configure on the transmitter CUSTOM SCRIPT page
      • suggested switch = "SA"
      • suggested mins = 3
      • suggested sw_high = 0
    • screen image:
      Could not load image
      count-dn.lua mix script
  • count-up.lua
    • copy to /SCRIPTS/FUNCTIONS
    • configure on the transmitter SPECIAL FUNCTIONS page
      • suggested switch SA(down)
    • screen image:
      Could not load image
      count-up.lua function script
  • shocount.lua
    • copy to /SCRIPTS/TELEMETRY
    • configure on the transmitter TELEMETRY page
    • screen image:
      Could not load image
      shocount.lua function script

Script sources:

count-dn.lua

-- these globals can be referenced in function and telemetry scripts
gCountUp = 0
gCountDown = 0
local target
local running = false
local complete = false
local announcements = { 720, 660, 600, 540, 480, 420, 360, 300, 240, 180, 120, 105, 90, 75, 60, 55, 50, 45, 40, 35, 30, 29, 28, 27, 26, 25, 24, 23, 22, 21, 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0}
local annIndex -- index into the announcements table (1 based)
local minUnit -- used by playNumber() for unit announcement
local input =
{
{ "switch", SOURCE}, -- switch used to activate count down
{ "mins", VALUE, 1, 12, 2 }, -- minutes to count down
{ "sw_high", VALUE, 0, 1, 1 } -- 0 = active when low, otherwise active when high
}
local output = {"ctup", "ctdn" }
local function init()
local version = getVersion()
if version < "2.1" then
minUnit = 16 -- unit for minutes in OpenTX 2.0
elseif version < "2.2" then
minUnit = 23 -- unit for minutes in OpenTX 2.1
else
minUnit = 25 -- unit for minutes in OpenTX 2.2
end
end
local function countdownIsRunning(switch, sw_high)
-- evaluate switch - return true if we should be counting down
if (sw_high > 0) then
return (switch > -1000)
else
return (switch < 1000)
end
end
local function run(switch, mins, sw_high)
local timenow = getTime() -- 10ms tick count
local minutes
local seconds
if (not countdownIsRunning(switch, sw_high)) then
running = false
complete = false
return 0, 0 -- ***** NOTE: early exit *****
end
if (complete) then
return 0, 0 -- must reset the switch before we go again
end
if (not running) then
running = true
target = timenow + ((mins * 60) * 100)
annIndex = 1
end
gCountDown = math.floor(((target - timenow) / 100) + .7) -- + is adj. to for announcement lag
gCountUp = (mins * 60) - gCountDown
while gCountDown < announcements[annIndex] do
annIndex = annIndex + 1 -- catch up
end
if gCountDown == announcements[annIndex] then
minutes = math.floor(gCountDown / 60)
seconds = gCountDown % 60
if minutes > 0 then
playNumber(minutes, minUnit, 0)
end
if seconds > 0 then
playNumber(seconds, 0, 0)
end
annIndex = annIndex + 1
end
if gCountDown <= 0 then
playNumber(0,0,0)
running = false
gCountDown = 0
complete = true
end
return gCountUp * 10.24, gCountDown * 10.24
end
return { input=input, output=output, init=init, run=run }

count-up.lua

gCountUp = 0
local min = 5
local max = 30
local last = 0
local announcements = { 5, 10, 15, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29 }
local annIndex = 1
local function run(e)
if not (gCountUp == last) then
last = gCountUp
for key, value in pairs(announcements) do
if value == last then
playNumber(last, 0, 0)
end
end
end
end
return{run=run}

shocount.lua

-- these globals can be referenced in mix, function, and telemetry scripts
gCountUp = 0
gCountDown = 0
local function run(e)
lcd.clear()
lcd.drawText(1,1,"OpenTx Lua Data Sharing",0)
lcd.drawText(1,11,"gCountUp:", 0)
lcd.drawText(lcd.getLastPos()+2,11,gCountUp,0)
lcd.drawText(1, 21, "gCountDown:", 0)
lcd.drawText(lcd.getLastPos()+2,21,gCountDown,0)
end
return{run=run}