--[[

SCRIPT: stick2rate.lua
AUTHOR: Mike Shellim
URL: http://rc-soar.com/opentx
DATE: 14 Sept 2014
VERSION: 1.0
DESCRIPTION:

Script to convert stick position into rate command.
Typical usage: for controlling a gimbal for smoother control and 'nudging'.
Pull SH to recentre

TESTED
OpenTx v. 2.08

INPUTS
ctrl: control stick 'ail' (default), 'ele', 'thr', 'rud'
Sens: sensitivity (1 - 100, default = 50)

INSTALLATION
1. Save script with .LUA extension, store in /SCRIPTS/MIXES folder on SD Card
2. Open Custom Scripts menu in the transmitter
3. Assign this script to empty slot
4. Open script, and test by moving aileron stick and observing 'gimb' output
5. Close Scripts menu
6. Check that [i]gimb appears in the mixer Src list

MIXER SETUP
- In the gimbal channel, create single mixer line, call it 'gimbal'
- Specify Src = [i]gimb
--]]


local gimbal = 0	--
local control_id = {}  	-- array of control ids
local SENS_ADJUST = 2048

-------------------
-- inputs / outputs
-------------------

local inp =
    {
        { "ctrl", VALUE, 1, 4, 1},		-- index into array of control. Default = 1, i.e ail
        { "sens", VALUE, 1, 100, 50 }	-- sensitivity
    }
local out = {"gimbal"} 	-- output position

----------------------------
-- initialisation function
----------------------------

local function init_func()

    -- Store ids of permissable gimbal controls
    -- (saves expensive lookups in run_func)

    control_id [1] = getFieldInfo ("ail").id
    control_id [2] = getFieldInfo ("ele").id
    control_id [3] = getFieldInfo ("rud").id
    control_id [4] = getFieldInfo ("thr").id

    -- switch SH

    control_id [5] = getFieldInfo ("sh").id

end

-------------------------------
-- periodically called function
-------------------------------

local function run_func(ctrl, sens)

    -- Is user re-centring?

    if getValue (control_id[5]) == 1024 then

        -- Recentring

        gimbal = 0

    else -- (not recentring)

        -- Get stick position

        local pos = getValue (control_id[ctrl])

        -- integrate gimbal position

        gimbal = gimbal + pos * (sens / SENS_ADJUST)

        -- handle end stop condition

        if gimbal > 1024 then

            gimbal = 1024

        elseif gimbal < -1024 then

            gimbal = -1024

        end

    end

    -- done

    return gimbal
end

return {init=init_func, run=run_func, input=inp, output=out}