Overview

With OpenTx 2.2 it is possible to have multiple GPS sensors, each with their own set of telemetry values which may have user-assigned names.

Value names are case sensitive and may include some or all of the following:

• GPS (latitude and longitude as a lua table containing [lat] and [lng])

• GSpd (speed in knots)

• GAlt (altitude in meters)

• Date (gps date converted to local time as a lua table containing [year] [mon] [day] [hour] [min] [sec])

• Hdg (heading in degrees true)

This example demonstrates getting latitude and longitude from a sensor with the default name of 'GPS'

Deprecated Functions

lcd.Lock() is deprecated, will be obsolete in 2.2. Lua scripts must now explicitly call lcd.Clear() and re-draw the whole display if necessary.

TODO: research killEvents() and use of keys in telemetry scripts

Obsolete Telemetry Field Names

OpenTX since version 2.1 provides more flexibility in the number and type of supported remote sensors. As a result, several field name constants are obsolete and need to be modified in scripts originally written for OpenTX 2.0.

GPS field names are covered in Handling GPS Sensor Data

Lipo voltage field names (LVSS) are covered in Handling Lipo Sensor Data

Maintaining compatibility with OpenTX 2.0

Automatic invocation of the background function - Beginning in OpenTX 2.1 the background() function is called automatically prior to each invocation of the run() function. Under 2.0 you must explicitly call your background function within your run function.

The handling of telemetry data is significantly improved in OpenTX 2.1. However, in order to support the additional flexibility of having multiple sensors of the same type, many Lua scripts referencing GPS and Lipo sensor data will require revision.

This section also covers some of the requirements for scripts that are necessary for them to function properly under both OpenTX 2.1 and OpenTX 2.0.

With OpenTx 2.2 it is possible to have multiple Lipo sensors, each with a user-assigned name. The call to getValue() returns a table with the current voltage of each of the cells it is monitoring.

This example demonstrates getting Lipo cell voltage from a sensor with the default name of 'Cels'

Example:

local cellValue = "unknown"
local cellResult = nil
local cellID = nil

local function getTelemetryId(name)
    field = getFieldInfo(name)
    if field then
      return field.id
    else
      return -1
    end
end

local function init()
  cellId = getTelemetryId("Cels")
end

local function background()
  cellResult = getValue(cellId)
  if (type(cellResult) == "table") then
    cellValue = ""
    for i, v in ipairs(cellResult) do
      cellValue = cellValue .. i .. ": " .. v .. " "
    end
  else
    cellValue = "telemetry not available"
  end
end

local function run(e)
  background()
  lcd.clear()
  lcd.drawText(1,1,"OpenTX 2.2 cell voltage example",0)
  lcd.drawText(1,11,"Cels:", 0)
  lcd.drawText(lcd.getLastPos()+2,11,cellValue,0)
end

return{init=init,run=run,background=background}