Reciver - I/O

-- Reciver by CFG

local reciveSide = "back"
local clockSide = "left"
local listen = false
local parityBit = 0
local counter = 0
local Byte = ""


local bin2hex = {
    ["0000"] = "0",
    ["0001"] = "1",
    ["0010"] = "2",
    ["0011"] = "3",
    ["0100"] = "4",
    ["0101"] = "5",
    ["0110"] = "6",
    ["0111"] = "7",
    ["1000"] = "8",
    ["1001"] = "9",
    ["1010"] = "A",
    ["1011"] = "B",
    ["1100"] = "C",
    ["1101"] = "D",
    ["1110"] = "E",
    ["1111"] = "F"
}

function Bin2Hex(s)

    local l = 0
    local h = ""
    local b = ""
    local rem

    l = string.len(s)
    rem = l % 4
    l = l-1
    h = ""

    -- need to prepend zeros to eliminate mod 4
    if (rem > 0) then
        s = string.rep("0", 4 - rem)..s
    end

    for i = 1, l, 4 do
        b = string.sub(s, i, i+3)
        h = h..bin2hex[b]
    end

    return h

end


function fromhex(str)
    return (str:gsub('..', function (cc)
        return string.char(tonumber(cc, 16))
    end))
end

term.clear()
term.setCursorPos(1,1)
print("Calafrica Group -- Calaofeng FrSky XM+ 1CH SBUS 2021 Full Range\n\n")
print("Waiting for start of text")

while true do
    if rs.getInput(clockSide) and rs.getInput(reciveSide) then
        listen = true
        print("Listening:\n")
        os.sleep(0.2)
        while listen do
            os.sleep(0.2)

            if rs.getInput(clockSide) and rs.getInput(reciveSide) ~= true then
                os.sleep(0.2)
                if rs.getInput(reciveSide) and parityBit % 2 == 0 then
                    print("String validated")
                elseif not rs.getInput(reciveSide) and parityBit % 2 ~=  0 then
                    print("String validated")
                else
                    print("Stringa not validated")
                end
                os.sleep(0.2)
                listen = false
            else
                if rs.getInput(reciveSide) then
                    byte = byte .. "1"
                    parityBit = parityBit + 1
                else
                    byte = byte .. "0"
                end
                counter = counter + 1
            end
        end
        hexText = Bin2Hex(byte)
        print("Recived text: "..fromhex(hexText))

    end
    parityBit = 0
    counter = 0
    byte = ""
    os.sleep(0.1)
end