Quad Race Start Sequence with random start tone

GoRace.lua

--%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

-- Modified from https://github.com/RCdiy/OpenTXLua/tree/master/FUNCTIONS/GoRace
-- http://rcdiy.ca/quad-race-start-sequence-gorace/
-- Jye Smith
-- 21/01/2019

--%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

-- License https://www.gnu.org/licenses/gpl-3.0.en.html
-- OpenTX Lua script
-- FUNCTIONS
--
-- File Locations On The Transmitter's SD Card
--  This script file  /SCRIPTS/FUNCTIONS/
-- 	Accompanying sound files /SCRIPTS/FUNCTIONS/GoRace/

-- Works On OpenTX Companion Version: 2.2

-- Author: Dean Church
-- Web: n/a

-- Thanks: Dean Church

-- Date: 2017 November 30
-- Update: 2017 December 2 RCdiy

-- Changes/Additions:
--  Removed debug code
--	Changed how switch position UP, Down, Middle is implemented
--  Removed seperate function calls; Rewrote run function.

-- To do: n/a

-- Description
--
-- 	A race timer suitable for quad racing.
--  An announcement to get ready to race is made. After a random delay of
--  upto 5 seconds a start buzzer sound is made.

-- 	Race quads starting sequence
-- 		Racers
--			Place their quads on the start line and check to make sure their
--				quad 'arms' ( motors spool up). They then disarm.
-- 			Return to their seat, put on their goggles and wait for instructions.
-- 		Race Starter
--			Asks for a 'thumbs up' from racers when they are ready.
-- 			Instructs racers to arm their quads.
--   			(spool up motors but remain stationary at the start line)
--   			"Pilots arm your quads, we go live on the tone is less then five."
--   		After a delay of up to 5 seconds the start tone sounds.
-- 		Racers take off from the start line and begin to race.
-- 			https://youtu.be/2Y0zDKB0FaU

-- Configurations
--  For help using functions scripts
--    http://rcdiy.ca/getting-started-with-lua-function-scripts/
--	Configure this script to run as a function script.
--	Select the switch "ON" as the switch and condition in the 1st column.
--		ON	Play Script	GoRace

local startRaceSwitch = "sa"							-- Triggers announcement
local startRaceSwitchPosition = "MIDDLE" 				-- Switch active position "TOWARDS", "AWAY" or "MIDDLE"
local randomTimeMilliseconds = 5000						-- Maximum delay

local audioDir         = "/SCRIPTS/FUNCTIONS/GoRace/" 	-- Location of script audio files
local raceStartPreface = audioDir.."GoRace.wav"	      	-- Prepare to race announcement
local startTone 	   = audioDir.."RaceTone.wav"	  	-- Race start sound

-- AVOID EDITING BELOW HERE

-- local DOWN, MIDDLE, UP = 1024, 0, -1024  --Switch position DOWN/Toward, MIDDLE, UP/Away
if startRaceSwitchPosition == "TOWARDS" then startRaceSwitchPosition = 1024 end
if startRaceSwitchPosition == "MIDDLE" then startRaceSwitchPosition = 0 end
if startRaceSwitchPosition == "AWAY" then startRaceSwitchPosition = -1024 end

local startRaceSwitchID
local startRaceSwitchVal = 0
local raceStartPrefaceLengthMilliseconds = 7000	-- Time to play raceStartPreface in milliSeconds
local startTonePlayed = true

local targetTimeMilliseconds = 0
local presentTimeMilliseconds = 0
local startSequenceReset = true

local function init()
	startRaceSwitchID	= getFieldInfo(startRaceSwitch).id --getTelemetryId(startRaceSwitch)
end	--init()

local function run()

	presentTimeMilliseconds = getTime()*10
	startRaceSwitchVal = getValue(startRaceSwitchID)

	if startRaceSwitchVal == startRaceSwitchPosition and startSequenceReset == true then
		startSequenceReset = false
		startTonePlayed = false
		math.randomseed(presentTimeMilliseconds)
		targetTimeMilliseconds = presentTimeMilliseconds + raceStartPrefaceLengthMilliseconds + math.random(randomTimeMilliseconds)
		playFile(raceStartPreface)
	end
	
	if presentTimeMilliseconds > targetTimeMilliseconds and startTonePlayed == false then
		startTonePlayed = true
		playFile(startTone)
	end
	
	if startRaceSwitchVal ~= startRaceSwitchPosition then
		startSequenceReset = true
		startTonePlayed = true
	end

end	-- run()

return { init=init, run=run }