-- $Id$:

-- Last updated: 2012.08.24

-- Version 1.10

library ieee;
use ieee.std_logic_1164.all;

-- ================================================


entity spi_deserialiser is
port
        (
        mrst            : in    std_logic; -- master reset
        mclk            : in    std_logic; -- master clock 100kHz

        spi_par_back_in : in    std_logic_vector(38 downto 0);

        spi_clk_en      : in    std_logic; -- spi clock input
        spi_str_in      : in    std_logic; -- spi strobe input
        spi_data_in     : in    std_logic; -- spi data input
        spi_data_out    : out   std_logic; -- spi data output

        spi_par_out     : out   std_logic_vector(38 downto 0)
        );

end spi_deserialiser;


-- ================================================

architecture a of spi_deserialiser is


signal spi_par_out_0  : std_logic_vector( 38 downto 0);
signal spi_par_back   : std_logic_vector( 38 downto 0);

signal toggle         : std_logic;


-- ================================================

begin

-- shift in and out data :

shift_data_in: process(mclk, mrst)

    begin
            if rising_edge(mclk) then
                if mrst = '1' then
                    spi_par_out   <= (others => '0');
                    spi_par_out_0 <= (others => '0');
                    spi_par_back  <= (others => '0');
                    toggle        <= '0';

                elsif spi_clk_en = '1' then
                    --spi_data_out <= spi_par_out_0(38);
                    spi_par_out_0 <= spi_par_out_0(37 downto 0) & spi_data_in;
                    spi_par_back  <= spi_par_back (37 downto 0) & (toggle and not spi_str_in);
                    toggle <= not toggle;

                    if  spi_str_in = '1' then

                        spi_par_out <= spi_par_out_0;

                        spi_par_back <= spi_par_back_in;
                        toggle <= '1';

                    end if;
                end if;

            end if;

    end process;

    spi_data_out <= spi_par_back(38);


-- ================================================

end;