---------------------------------------------------------------------------------- Company: -- Engineer:---- Create Date:    08:53:26 04/27/05-- Design Name:    -- Module Name:    loopback - Behavioral-- Project Name:   -- Target Device:  -- Tool versions:  -- Description:---- Dependencies:-- -- Revision:-- Revision 0.01 - File Created-- Additional Comments:-- --------------------------------------------------------------------------------library IEEE;use IEEE.STD_LOGIC_1164.ALL;use IEEE.STD_LOGIC_ARITH.ALL;use IEEE.STD_LOGIC_UNSIGNED.ALL;---- Uncomment the following library declaration if instantiating---- any Xilinx primitives in this code.--library UNISIM;--use UNISIM.VComponents.all;entity loopback is    Port ( clk : in std_logic;           rst : in std_logic;           leds : out std_logic_vector(7 downto 0);           switches : in std_logic_vector(7 downto 0);           rs232_rx : in std_logic;           rs232_tx : out std_logic;
			  lock     : out std_logic);end loopback;architecture Behavioral of loopback is	COMPONENT program		PORT		   (			 address     : IN std_logic_vector(9 downto 0);			 clk         : IN std_logic;          			 instruction : OUT std_logic_vector(17 downto 0)			);		END COMPONENT;		-- Program memory signals		signal address      : std_logic_vector (9 downto 0);
   COMPONENT my_dcm	PORT(		CLKIN_IN : IN std_logic;          		CLKFX_OUT : OUT std_logic;		CLKIN_IBUFG_OUT : OUT std_logic;		CLK0_OUT : OUT std_logic;		LOCKED_OUT : OUT std_logic		);	END COMPONENT;
	COMPONENT kcpsm3		PORT(			instruction   : IN std_logic_vector(17 downto 0);			in_port       : IN std_logic_vector(7 downto 0);			interrupt     : IN std_logic;			reset         : IN std_logic;			clk           : IN std_logic;          			address       : OUT std_logic_vector(9 downto 0);			port_id       : OUT std_logic_vector(7 downto 0);			write_strobe  : OUT std_logic;			out_port      : OUT std_logic_vector(7 downto 0);			read_strobe   : OUT std_logic;			interrupt_ack : OUT std_logic			);		END COMPONENT;		-- PicoBlaze Signals		signal instruction  : std_logic_vector (17 downto 0);		signal port_id      : std_logic_vector (7 downto 0);		signal write_strobe : std_logic;		signal in_port      : std_logic_vector (7 downto 0);		signal out_port     : std_logic_vector (7 downto 0);		signal read_strobe  : std_logic;		COMPONENT uart_rx			PORT			(			  serial_in           : IN std_logic;			  read_buffer         : IN std_logic;			  reset_buffer        : IN std_logic;			  en_16_x_baud        : IN std_logic;			  clk                 : IN std_logic;          			  data_out            : OUT std_logic_vector(7 downto 0);			  buffer_data_present : OUT std_logic;			  buffer_full         : OUT std_logic;			  buffer_half_full    : OUT std_logic			);		END COMPONENT;		COMPONENT uart_tx		PORT		(			data_in          : IN std_logic_vector(7 downto 0);			write_buffer     : IN std_logic;			reset_buffer     : IN std_logic;			en_16_x_baud     : IN std_logic;			clk              : IN std_logic;          			serial_out       : OUT std_logic;			buffer_full      : OUT std_logic;			buffer_half_full : OUT std_logic		);		END COMPONENT;		-- UART signals		signal baud_count      : std_logic_vector (8 downto 0);		signal en_16_x_baud    : std_logic;		signal read_from_uart  : std_logic;  		signal rx_data         : std_logic_vector(7 downto 0);  		signal data_present    : std_logic;		signal write_to_uart   : std_logic;		signal write_to_leds   : std_logic;		signal buffer_full     : std_logic;
      signal rst_in          : std_logic;
      signal clk50MHz        : std_logic;begin-- Instantiate PicoBlaze and the instruction ROM.  This is simply-- cut and paste from the example designs that come with PicoBlaze.-- Interrupts are not used for this design.
   rst_in <= not rst;	my_kcpsm3: kcpsm3 	   PORT MAP		(			address       => address,			instruction   => instruction,			port_id       => port_id,			write_strobe  => write_strobe,			out_port      => out_port,			read_strobe   => read_strobe,			in_port       => in_port,			interrupt     => '0',			interrupt_ack => open,			reset         => rst_in,			clk           => clk50MHz		);	my_program: program 	   PORT MAP		(		   address     => address,		   instruction => instruction,		   clk         => clk50MHz		);   Inst_my_dcm: my_dcm PORT MAP(		CLKIN_IN => clk,		CLKFX_OUT => clk50MHz,		CLKIN_IBUFG_OUT => open,		CLK0_OUT => open,		LOCKED_OUT => lock	);-- Implement the 16x bit rate counter for the uart transmit and receive.-- The system clock is 50 MHz, and the desired baud rate is 9600.  I used-- the formula in the documentation to calculate the terminal count value.	baudgen: process (clk50MHz,rst_in)	begin     	if rst_in = '1' then      	baud_count <= "000000000";			en_16_x_baud <= '0';   	elsif (clk50MHz'event and clk50MHz = '1') then      	if (baud_count = X"145")then		  		baud_count <= "000000000";		  		en_16_x_baud <= '1';      	else		  		baud_count <= baud_count + 1;        		en_16_x_baud <= '0';      	end if;   	end if;	end process;	   -- Implement the output port logic:      --   leds_out, port 01      --   uart_data_tx, port 03	write_to_uart <= write_strobe and port_id(0) and port_id(1);   write_to_leds <= write_strobe and port_id(0);  process (clk50MHz,rst_in)	begin  	  if (clk50MHz'event and clk50MHz='1') then	  	 if rst_in = '1'	then	      leds <= "00000000";	    elsif(write_to_leds = '1') then	        leds <= out_port;       end if;     end if;	end process;   transmit: uart_tx 	PORT MAP	(		data_in          => out_port,		write_buffer     => write_to_uart,		reset_buffer     => rst_in,		en_16_x_baud     => en_16_x_baud,		serial_out       => rs232_tx,		buffer_full      => open,		buffer_half_full => open,		clk              => clk50MHz	);	--  Implement the input port logic:      --  switch_in, port 00      --  uart_data_rx, port 02      --  data_present, port 04      --  buffer_full, port 05	process (clk50MHz,rst_in)	begin     	if (clk50MHz'event and clk50MHz = '1') then			if rst_in = '1' then      		in_port <= "00000000";      		read_from_uart <= '0';			else      		case (port_id) is        			when X"00" =>							in_port <= switches;        			when X"02" =>						in_port <= rx_data;        			when X"04" =>							in_port <= "0000000" & data_present;					when X"05" =>							in_port <= "0000000" & buffer_full;        			when others =>						in_port <= "00000000";      		end case;      	end if;			read_from_uart <= read_strobe and port_id(2);		end if;	end process;  	receive: uart_rx 	PORT MAP	(		serial_in           => rs232_rx,		data_out            => rx_data,		read_buffer         => read_from_uart,		reset_buffer        => rst_in,		en_16_x_baud        => en_16_x_baud,		buffer_data_present => data_present,		buffer_full         => open,		buffer_half_full    => open,		clk                 => clk50MHz	); end Behavioral;