-------------------------------------------------------------------------------
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-------------------------------------------------------------------------------
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--
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--
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-- Copyright (C) 2009, 2010 Dr. Juergen Sauermann
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-- Copyright (C) 2009, 2010 Dr. Juergen Sauermann
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--
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--
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-- This code is free software: you can redistribute it and/or modify
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-- This code is free software: you can redistribute it and/or modify
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-- it under the terms of the GNU General Public License as published by
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-- it under the terms of the GNU General Public License as published by
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-- the Free Software Foundation, either version 3 of the License, or
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-- the Free Software Foundation, either version 3 of the License, or
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-- (at your option) any later version.
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-- (at your option) any later version.
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--
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--
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-- This code is distributed in the hope that it will be useful,
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-- This code is distributed in the hope that it will be useful,
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-- but WITHOUT ANY WARRANTY; without even the implied warranty of
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-- but WITHOUT ANY WARRANTY; without even the implied warranty of
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-- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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-- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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-- GNU General Public License for more details.
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-- GNU General Public License for more details.
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--
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--
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-- You should have received a copy of the GNU General Public License
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-- You should have received a copy of the GNU General Public License
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-- along with this code (see the file named COPYING).
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-- along with this code (see the file named COPYING).
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-- If not, see http://www.gnu.org/licenses/.
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-- If not, see http://www.gnu.org/licenses/.
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--
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--
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-------------------------------------------------------------------------------
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-------------------------------------------------------------------------------
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-------------------------------------------------------------------------------
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-------------------------------------------------------------------------------
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--
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--
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-- Module Name: io - Behavioral
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-- Module Name: io - Behavioral
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-- Create Date: 13:59:36 11/07/2009
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-- Create Date: 13:59:36 11/07/2009
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-- Description: the I/O of a CPU (uart and general purpose I/O lines).
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-- Description: the I/O of a CPU (uart and general purpose I/O lines).
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--
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--
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-------------------------------------------------------------------------------
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-------------------------------------------------------------------------------
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--
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--
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library IEEE;
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library IEEE;
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use IEEE.STD_LOGIC_1164.ALL;
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use IEEE.STD_LOGIC_1164.ALL;
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use IEEE.STD_LOGIC_ARITH.ALL;
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use IEEE.STD_LOGIC_ARITH.ALL;
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use IEEE.STD_LOGIC_UNSIGNED.ALL;
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use IEEE.STD_LOGIC_UNSIGNED.ALL;
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entity io is
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entity io is
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port ( I_CLK : in std_logic;
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port ( I_CLK : in std_logic;
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I_CLR : in std_logic;
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I_CLR : in std_logic;
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I_ADR_IO : in std_logic_vector( 7 downto 0);
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I_ADR_IO : in std_logic_vector( 7 downto 0);
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I_DIN : in std_logic_vector( 7 downto 0);
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I_DIN : in std_logic_vector( 7 downto 0);
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I_SWITCH : in std_logic_vector( 7 downto 0);
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I_SWITCH : in std_logic_vector( 7 downto 0);
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I_RD_IO : in std_logic;
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I_RD_IO : in std_logic;
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I_RX : in std_logic;
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I_RX : in std_logic;
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I_WE_IO : in std_logic;
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I_WE_IO : in std_logic;
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Q_7_SEGMENT : out std_logic_vector( 6 downto 0);
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Q_7_SEGMENT : out std_logic_vector( 6 downto 0);
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Q_DOUT : out std_logic_vector( 7 downto 0);
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Q_DOUT : out std_logic_vector( 7 downto 0);
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Q_INTVEC : out std_logic_vector( 5 downto 0);
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Q_INTVEC : out std_logic_vector( 5 downto 0);
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Q_LEDS : out std_logic_vector( 1 downto 0);
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Q_LEDS : out std_logic_vector( 1 downto 0);
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Q_TX : out std_logic);
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Q_TX : out std_logic);
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end io;
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end io;
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architecture Behavioral of io is
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architecture Behavioral of io is
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component uart
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component uart
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generic(CLOCK_FREQ : std_logic_vector(31 downto 0);
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generic(CLOCK_FREQ : std_logic_vector(31 downto 0);
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BAUD_RATE : std_logic_vector(27 downto 0));
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BAUD_RATE : std_logic_vector(27 downto 0));
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port( I_CLK : in std_logic;
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port( I_CLK : in std_logic;
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I_CLR : in std_logic;
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I_CLR : in std_logic;
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I_RD : in std_logic;
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I_RD : in std_logic;
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I_WE : in std_logic;
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I_WE : in std_logic;
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I_RX : in std_logic;
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I_RX : in std_logic;
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I_TX_DATA : in std_logic_vector(7 downto 0);
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I_TX_DATA : in std_logic_vector(7 downto 0);
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Q_RX_DATA : out std_logic_vector(7 downto 0);
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Q_RX_DATA : out std_logic_vector(7 downto 0);
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Q_RX_READY : out std_logic;
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Q_RX_READY : out std_logic;
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Q_TX : out std_logic;
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Q_TX : out std_logic;
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Q_TX_BUSY : out std_logic);
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Q_TX_BUSY : out std_logic);
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end component;
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end component;
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signal U_RX_READY : std_logic;
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signal U_RX_READY : std_logic;
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signal U_TX_BUSY : std_logic;
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signal U_TX_BUSY : std_logic;
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signal U_RX_DATA : std_logic_vector( 7 downto 0);
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signal U_RX_DATA : std_logic_vector( 7 downto 0);
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signal L_INTVEC : std_logic_vector( 5 downto 0);
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signal L_INTVEC : std_logic_vector( 5 downto 0);
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signal L_LEDS : std_logic;
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signal L_LEDS : std_logic;
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signal L_RD_UART : std_logic;
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signal L_RD_UART : std_logic;
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signal L_RX_INT_ENABLED : std_logic;
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signal L_RX_INT_ENABLED : std_logic;
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signal L_TX_INT_ENABLED : std_logic;
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signal L_TX_INT_ENABLED : std_logic;
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signal L_WE_UART : std_logic;
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signal L_WE_UART : std_logic;
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begin
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begin
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urt: uart
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urt: uart
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generic map(CLOCK_FREQ => std_logic_vector(conv_unsigned(25000000, 32)),
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generic map(CLOCK_FREQ => std_logic_vector(conv_unsigned(25000000, 32)),
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BAUD_RATE => std_logic_vector(conv_unsigned( 38400, 28)))
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BAUD_RATE => std_logic_vector(conv_unsigned( 38400, 28)))
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port map( I_CLK => I_CLK,
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port map( I_CLK => I_CLK,
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I_CLR => I_CLR,
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I_CLR => I_CLR,
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I_RD => L_RD_UART,
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I_RD => L_RD_UART,
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I_WE => L_WE_UART,
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I_WE => L_WE_UART,
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I_TX_DATA => I_DIN(7 downto 0),
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I_TX_DATA => I_DIN(7 downto 0),
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I_RX => I_RX,
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I_RX => I_RX,
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Q_TX => Q_TX,
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Q_TX => Q_TX,
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Q_RX_DATA => U_RX_DATA,
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Q_RX_DATA => U_RX_DATA,
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Q_RX_READY => U_RX_READY,
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Q_RX_READY => U_RX_READY,
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Q_TX_BUSY => U_TX_BUSY);
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Q_TX_BUSY => U_TX_BUSY);
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-- IO read process
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-- IO read process
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--
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--
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iord: process(I_ADR_IO, I_SWITCH,
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iord: process(I_ADR_IO, I_SWITCH,
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U_RX_DATA, U_RX_READY, L_RX_INT_ENABLED,
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U_RX_DATA, U_RX_READY, L_RX_INT_ENABLED,
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U_TX_BUSY, L_TX_INT_ENABLED)
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U_TX_BUSY, L_TX_INT_ENABLED)
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begin
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begin
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-- addresses for mega8 device (use iom8.h or #define __AVR_ATmega8__).
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-- addresses for mega8 device (use iom8.h or #define __AVR_ATmega8__).
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--
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--
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case I_ADR_IO is
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case I_ADR_IO is
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when X"2A" => Q_DOUT <= -- UCSRB:
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when X"2A" => Q_DOUT <= -- UCSRB:
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L_RX_INT_ENABLED -- Rx complete int enabled.
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L_RX_INT_ENABLED -- Rx complete int enabled.
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& L_TX_INT_ENABLED -- Tx complete int enabled.
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& L_TX_INT_ENABLED -- Tx complete int enabled.
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& L_TX_INT_ENABLED -- Tx empty int enabled.
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& L_TX_INT_ENABLED -- Tx empty int enabled.
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& '1' -- Rx enabled
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& '1' -- Rx enabled
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& '1' -- Tx enabled
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& '1' -- Tx enabled
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& '0' -- 8 bits/char
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& '0' -- 8 bits/char
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& '0' -- Rx bit 8
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& '0' -- Rx bit 8
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& '0'; -- Tx bit 8
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& '0'; -- Tx bit 8
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when X"2B" => Q_DOUT <= -- UCSRA:
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when X"2B" => Q_DOUT <= -- UCSRA:
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U_RX_READY -- Rx complete
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U_RX_READY -- Rx complete
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& not U_TX_BUSY -- Tx complete
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& not U_TX_BUSY -- Tx complete
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& not U_TX_BUSY -- Tx ready
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& not U_TX_BUSY -- Tx ready
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& '0' -- frame error
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& '0' -- frame error
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& '0' -- data overrun
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& '0' -- data overrun
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& '0' -- parity error
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& '0' -- parity error
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& '0' -- double dpeed
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& '0' -- double dpeed
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& '0'; -- multiproc mode
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& '0'; -- multiproc mode
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when X"2C" => Q_DOUT <= U_RX_DATA; -- UDR
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when X"2C" => Q_DOUT <= U_RX_DATA; -- UDR
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when X"40" => Q_DOUT <= -- UCSRC
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when X"40" => Q_DOUT <= -- UCSRC
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'1' -- URSEL
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'1' -- URSEL
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& '0' -- asynchronous
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& '0' -- asynchronous
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& "00" -- no parity
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& "00" -- no parity
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& '1' -- two stop bits
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& '1' -- two stop bits
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& "11" -- 8 bits/char
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& "11" -- 8 bits/char
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& '0'; -- rising clock edge
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& '0'; -- rising clock edge
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when X"36" => Q_DOUT <= I_SWITCH; -- PINB
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when X"36" => Q_DOUT <= I_SWITCH; -- PINB
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when others => Q_DOUT <= X"AA";
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when others => Q_DOUT <= X"AA";
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end case;
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end case;
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end process;
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end process;
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-- IO write process
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-- IO write process
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--
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--
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iowr: process(I_CLK)
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iowr: process(I_CLK)
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begin
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begin
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if (rising_edge(I_CLK)) then
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if (rising_edge(I_CLK)) then
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if (I_CLR = '1') then
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if (I_CLR = '1') then
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L_RX_INT_ENABLED <= '0';
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L_RX_INT_ENABLED <= '0';
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L_TX_INT_ENABLED <= '0';
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L_TX_INT_ENABLED <= '0';
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elsif (I_WE_IO = '1') then
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elsif (I_WE_IO = '1') then
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case I_ADR_IO is
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case I_ADR_IO is
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when X"38" => Q_7_SEGMENT <= I_DIN(6 downto 0); -- PORTB
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when X"38" => -- PORTB
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Q_7_SEGMENT <= I_DIN(6 downto 0);
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L_LEDS <= not L_LEDS;
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L_LEDS <= not L_LEDS;
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when X"40" => -- handled by uart
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when X"2A" => -- UCSRB
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when X"41" => -- handled by uart
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L_RX_INT_ENABLED <= I_DIN(7);
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when X"43" => L_RX_INT_ENABLED <= I_DIN(0);
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L_TX_INT_ENABLED <= I_DIN(6);
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L_TX_INT_ENABLED <= I_DIN(1);
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when X"2B" => -- UCSRA: handled by uart
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when X"2C" => -- UDR: handled by uart
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when X"40" => -- UCSRC/UBRRH: (ignored)
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when others =>
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when others =>
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end case;
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end case;
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end if;
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end if;
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end if;
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end if;
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end process;
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end process;
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-- interrupt process
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-- interrupt process
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--
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--
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ioint: process(I_CLK)
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ioint: process(I_CLK)
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begin
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begin
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if (rising_edge(I_CLK)) then
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if (rising_edge(I_CLK)) then
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if (I_CLR = '1') then
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if (I_CLR = '1') then
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L_INTVEC <= "000000";
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L_INTVEC <= "000000";
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else
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else
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if (L_RX_INT_ENABLED and U_RX_READY) = '1' then
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if (L_RX_INT_ENABLED and U_RX_READY) = '1' then
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if (L_INTVEC(5) = '0') then -- no interrupt pending
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if (L_INTVEC(5) = '0') then -- no interrupt pending
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L_INTVEC <= "101011"; -- _VECTOR(11)
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L_INTVEC <= "101011"; -- _VECTOR(11)
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end if;
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end if;
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elsif (L_TX_INT_ENABLED and not U_TX_BUSY) = '1' then
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elsif (L_TX_INT_ENABLED and not U_TX_BUSY) = '1' then
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if (L_INTVEC(5) = '0') then -- no interrupt pending
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if (L_INTVEC(5) = '0') then -- no interrupt pending
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L_INTVEC <= "101100"; -- _VECTOR(12)
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L_INTVEC <= "101100"; -- _VECTOR(12)
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end if;
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end if;
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else -- no interrupt
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else -- no interrupt
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L_INTVEC <= "000000";
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L_INTVEC <= "000000";
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end if;
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end if;
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end if;
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end if;
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end if;
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end if;
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end process;
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end process;
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L_WE_UART <= I_WE_IO when (I_ADR_IO = X"2C") else '0'; -- write UART UDR
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L_WE_UART <= I_WE_IO when (I_ADR_IO = X"2C") else '0'; -- write UART UDR
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L_RD_UART <= I_RD_IO when (I_ADR_IO = X"2C") else '0'; -- read UART UDR
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L_RD_UART <= I_RD_IO when (I_ADR_IO = X"2C") else '0'; -- read UART UDR
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Q_LEDS(1) <= L_LEDS;
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Q_LEDS(1) <= L_LEDS;
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Q_LEDS(0) <= not L_LEDS;
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Q_LEDS(0) <= not L_LEDS;
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Q_INTVEC <= L_INTVEC;
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Q_INTVEC <= L_INTVEC;
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end Behavioral;
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end Behavioral;
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