VTX Power switching via transmitter switch (Opentx/Betaflight/Tramp/Smartaudio)

vtx.lua

--
-- *Fixed version of wkochFPV for BF 3.5
-- Original: https://github.com/betaflight/betaflight/issues/3094#issuecomment-302953603
-- Note: If you put it on a 3-way switch and go from first to third position fast it may not register correctly so better step through slowly
--
-- *Changes:
-- Corrected loading of dependencies
-- Shortened filename to make it compatible with latest opentx restrictions
-- Added a condition in the script for pit mode (vtx power 0 alone didn't work for me)
--
-- *How To (Copy pasted from comment)
-- 1. Install betaflight-tx-lua-scripts as usual
-- 2. Install my script vtx.lua in /SCRIPTS/MIXES
-- 3. In model menu of your taranis go to LUA-scripts page and enable VTXprog.lua and configure as follows:
-- 4. Enter your desired band: 1="A", 2="B", 3="E", 4="F", 5="R" (unify pro!)
-- 5. Enter your desired channel: 1,2,3…
-- 6. Select “global variable 1” (GV1, or another free global variable) as input for TxPower
-- 7.Now configure any switch to adjust GV1 to the desired power level: 0=pit mode, 1=25mW, 2=200mW … (use special functions menu, select ‘adjust GV1’ as action, enter desired value). Use e.g. 0 for your switch neutral position, 1 for switch up, 2 for switch down, if you would like to select 25mw or 200mw based on switch position.
--

-- Load MSP smartport library

SCRIPT_HOME = "/SCRIPTS/BF"

protocol = assert(loadScript(SCRIPT_HOME.."/protocols.lua"))()
radio = assert(loadScript(SCRIPT_HOME.."/radios.lua"))()

assert(loadScript(radio.preLoad))()
assert(loadScript(protocol.transport))()
assert(loadScript(SCRIPT_HOME.."/MSP/common.lua"))()
-- define inputs
local inputs = {
        { "TxPower", SOURCE},                -- store requested TxPower in global variable, e.g. GV1
        { "TxBand", VALUE, 1, 5, 4 },
		{ "TxChannel", VALUE, 1, 8, 1 }
    }

-- Variables to store parameters last programmed to vtx
local lastPower = 0
local lastBand = 0
local lastChannel = 0

local MSP_VTX_SET_CONFIG = 89
local firstrun = 1

-- Returns payload to send to fc
local function VTXconfig(TxPower, TxBand, TxChannel,TxPitMode)
   local channel = (TxBand-1)*8 + TxChannel-1
   return { bit32.band(channel,0xFF), bit32.rshift(channel,8), TxPower, TxPitMode }  -- last 0 disables PIT mode
end
	
local function run(TxPower, TxBand, TxChannel)
    
	-- ignore any settings on first run of the script, send only further changes to vtx
	if firstrun == 1 then
		lastPower = TxPower
		lastBand = TxBand
		lastChannel = TxChannel
		firstrun = 0
	end
	
	if (lastPower ~= TxPower) or (lastBand ~= TxBand) or (lastChannel ~= TxChannel) then
		
		if TxPower > 0 then
			mspSendRequest(MSP_VTX_SET_CONFIG,VTXconfig(TxPower, TxBand, TxChannel,0))
			playFile("eng.wav")
		else
			mspSendRequest(MSP_VTX_SET_CONFIG,VTXconfig(TxPower, TxBand, TxChannel,1))
			playFile("eng.wav")
		end

		if TxPower == 0 then
			mspSendRequest(MSP_VTX_SET_CONFIG,VTXconfig(0, TxBand, TxChannel))
		end
		
		lastPower = TxPower
		lastBand = TxBand
		lastChannel = TxChannel
	end
	
	mspProcessTxQ()
	
    return
end

return {input=inputs, run=run}