------------------------------------------------------------------------------
--  This file is a part of the LPP VHDL IP LIBRARY
--  Copyright (C) 2009 - 2010, Laboratory of Plasmas Physic - CNRS
--
--  This program is free software; you can redistribute it and/or modify
--  it under the terms of the GNU General Public License as published by
--  the Free Software Foundation; either version 3 of the License, or
--  (at your option) any later version.
--
--  This program is distributed in the hope that it will be useful,
--  but WITHOUT ANY WARRANTY; without even the implied warranty of
--  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
--  GNU General Public License for more details.
--
--  You should have received a copy of the GNU General Public License
--  along with this program; if not, write to the Free Software
--  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA 
-------------------------------------------------------------------------------
--                    Author : Alexis Jeandet
--                     Mail : alexis.jeandet@lpp.polytechnique.fr
----------------------------------------------------------------------------
library IEEE;
use IEEE.numeric_std.all;
use IEEE.std_logic_1164.all;
library lpp;
use lpp.lpp_uart.all;

--! \brief A general purpose UART with automatic baudrate 
--! 
--! \author Alexis Jeandet alexis.jeandet@lpp.polytechnique.fr

entity UART is 
generic(Data_sz     :   integer :=  8);            --! Data width
port(
    clk         :   in  std_logic;                              --! System clock
    reset       :   in  std_logic;                              --! System reset
    TXD         :   out std_logic;                              --! UART Transmission pin
    RXD         :   in  std_logic;                              --! UART Reception pin
    Capture     :   in  std_logic;                              --! Automatic baudrate module reset
    NwDat       :   out std_logic;                              --! New data flag, means that a new data have been received by the UART
    ACK         :   in  std_logic;                              --! Acknowledge flag to clear NwDat flag
    Send        :   in  std_logic;                              --! To send a data you have to set this flag
    Sended      :   out std_logic;                              --! When this flag is set you can sed a new data
    BTrigger    :   out std_logic_vector(11 downto 0);          --! Baudrate generator current value, could be usefull if you whant to know the current value of the baudrate or of the oscillator (it suppose that you know baudrate)
    RDATA       :   out std_logic_vector(Data_sz-1 downto 0);   --! Current read word
    WDATA       :   in  std_logic_vector(Data_sz-1 downto 0)    --! Put here the word you whant to send
);
end entity;


architecture ar_UART of UART is
signal  Bclk    :   std_logic;

signal  RDATA_int       :   std_logic_vector(Data_sz+1 downto 0);
signal  WDATA_int       :   std_logic_vector(Data_sz+1 downto 0);

signal  TXD_Dummy       :   std_logic;
signal  NwDat_int       :   std_logic;
signal  NwDat_int_reg   :   std_logic;
signal  receive         :   std_logic;
constant zeroVect       :   std_logic_vector(Data_sz+1 downto 0) := (others => '0');

begin



WDATA_int   <=  '1' & WDATA & '0'; 

BaudGenerator : entity work.BaudGen
    port map(clk,reset,Capture,Bclk,RXD,BTrigger);


RX_REG  : entity work.Shift_REG
    generic map(Data_sz+2)
    port map(clk,Bclk,reset,RXD,TXD_Dummy,receive,NwDat_int,zeroVect,RDATA_int);

TX_REG  : entity work.Shift_REG
    generic map(Data_sz+2)
    port map(clk,Bclk,reset,'1',TXD,Send,Sended,WDATA_int);



process(clk,reset)
begin
    if reset = '0' then
        NwDat   <=  '0';
    elsif clk'event and clk = '1' then
        NwDat_int_reg   <=  NwDat_int;
        if RXD = '1' and NwDat_int = '1' then
            receive <=  '0';
        elsif RXD = '0' then
            receive <=  '1';
        end if;
        if NwDat_int_reg = '0' and NwDat_int = '1' then
            NwDat   <=  '1';
				RDATA   <=  RDATA_int(8 downto 1);
        elsif ack = '1' then
            NwDat   <=  '0';
        end if;
    end if;
end process;

end ar_UART;