rubberTurtleFarm 1.3.3

local t = turtle

local function forward(x)
    for i = 1, x do
        t.forward()
    end
end

local function rTurn(x)
    for i = 1, x do
        t.turnRight()
    end
end

local function lTurn(x)
    for i = 1, x do
        t.turnLeft()
    end
end

local function up(x)
    for i = 1, x do
        t.up()
    end
end

local function down(x)
    for i = 1, x do
        t.down()
    end
end

local function back(x)
    for i = 1, x do
        t.back()
    end
end

local function gotoStart()
    rs.setAnalogOutput("left", 0)
    os.sleep(1)
    up(2)
    back(1)
    lTurn(1)
    forward(1)
end

local function rowUp()
    for i = 1, 4, 1 do
        t.dig()
        up(1)
    end
end

local function rowDown()
    for i = 1, 4, 1 do
        t.dig()
        down(1)
    end
end

local facing = t.detect()

local height = t.detect(down)

local function harvest(x)
    for i = 1, x do
        if facing == true then
            if height == true then
                rowUp()
                rTurn(1)
            else
                rowDown()
                rTurn(1)
            end
        elseif facing == false then
            if height == true then
                forward(1)
                lTurn(1)
                rowUp()
                rTurn(1)
            else
                forward(1)
                lTurn(1)
                rowDown()
                rTurn(1)
            end
        end
    end
end

local function gotoHome()
    back(2)
    lTurn(1)
    forward(1)
    down(5)
    os.sleep(1)
    rs.setAnalogOutput("left", 15)
    os.sleep(3600)
end

while true do
    gotoStart()
    rowUp()
    harvest(6)
    gotoHome()
end