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-- Company: 
-- Engineer: 
-- 
-- Create Date:    16:04:58 09/23/2009 
-- Design Name: 
-- Module Name:    UARTDriver - beh 
-- Project Name: 
-- Target Devices: 
-- Tool versions: 
-- Description: 
--
-- Dependencies: 
--
-- Revision: 
-- Revision 0.01 - File Created
-- Additional Comments: 
--
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library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use IEEE.NUMERIC_STD.all;

-- clk and reset needed for UART state machine. tx_wire is output wire to UART connector. 
-- rx_wire is input wire from UART connector. 
entity UARTDriver is
   Port ( 
      clk : in  std_logic;
      reset : in  std_logic;
      enter_pb_not : in std_logic;
      LED_0_not : out std_logic;
      LED_1_not : out std_logic;
      LED_2_not : out std_logic;
      LED_3_not : out std_logic;
      rx_wire : in  std_logic;
      tx_wire : out  std_logic);
end UARTDriver;

-- This is just to demonstrate that the UART works. 
-- NOTE: Move Switch 3 DOWN to reset -- leave in UP position -- for normal operation
architecture beh of UARTDriver is
   signal tx_full, rx_empty : std_logic;
   signal trans_data: std_logic_vector(7 downto 0);
   signal enter_pb, enter_pb_stable, button_level : std_logic;
   signal tx_go : std_logic;

   begin

-- Invert button value for proper operation of debounce circuit
   enter_pb <= not enter_pb_not;

   UARTComponent: entity work.UARTUnit(beh)
      port map ( clk=>clk, reset=>reset, rd_uart=>tx_go, wr_uart=>tx_go, rx_wire=>rx_wire,
         tx_loc_sys_data=>trans_data, tx_full=>tx_full, rx_empty=>rx_empty, rx_loc_sys_data=>trans_data, tx_wire=>tx_wire);

-- Take the bounce out of the pushbutton (only works for buttons normally at 0 and then go to 1 when pressed!)
   DebounceInst: entity work.DEBOUNCE(beh) 
      port map (clk=>clk, reset=>reset, button=>enter_pb, button_level=>button_level, button_stable=>enter_pb_stable);

-- Pushbutton ENTER used to send byte back to computer serial port
   tx_go <= '1' when enter_pb_stable = '1' else '0';
-- Echo mode
--   tx_go <= not rx_empty;

-- LED is on when '0' is written. If rx_empty is '1' (NO DATA), then it writes a 0 turning ON the led.
   LED_0_not <= not rx_empty;
   LED_1_not <= not reset;
   LED_2_not <= not button_level;
   LED_3_not <= not tx_go;

end beh;