repo2/chameleon2/chameleon2_io_shiftreg.vhd @ 1476
| 872 | markw | -- -----------------------------------------------------------------------
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--
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-- Turbo Chameleon 64
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--
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-- Multi purpose FPGA expansion for the Commodore 64 computer
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--
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-- -----------------------------------------------------------------------
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-- Copyright 2005-2018 by Peter Wendrich (pwsoft@syntiac.com)
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-- http://www.syntiac.com
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--
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-- This source file is free software: you can redistribute it and/or modify
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-- it under the terms of the GNU Lesser General Public License as published
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-- by 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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--
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-- This source file 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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-- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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-- GNU General Public License for more details.
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--
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-- You should have received a copy of the GNU General Public License
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-- along with this program. If not, see <http://www.gnu.org/licenses/>.
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--
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-- -----------------------------------------------------------------------
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-- I/O controller entity for the shiftregister controlling PS/2,
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-- LEDs and reset signals on Turbo Chameleon 64 second edition.
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--
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-- -----------------------------------------------------------------------
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-- clk - System clock
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--
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-- ser_out_clk - Serial clock, connect on toplevel to port with same name
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-- ser_out_dat - Serial data, connect on toplevel to port with same name
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-- ser_out_rclk - Serial strobe, connect on toplevel to port with same name
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--
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-- reset_c64 - Active high, pulls reset on the cartridge port
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-- reset_iec - Active high, pulls reset on teh IEC connector
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-- ps2_mouse_clk - Open drain output for PS/2 mouse clock (active low)
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-- ps2_mouse_dat - Open drain output for PS/2 mouse data (active low)
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-- ps2_keybard_clk - Open drain output for PS/2 keyboard clock (active low)
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-- ps2_keybard_dat - Open drain output for PS/2 keyboard data (active low)
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-- led_green - Active high, enable the green LED
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-- led_red - Active high, enable the red LED
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-- -----------------------------------------------------------------------
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library ieee;
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use ieee.std_logic_1164.all;
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use ieee.numeric_std.all;
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-- -----------------------------------------------------------------------
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entity chameleon2_io_shiftreg is
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port (
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clk : in std_logic;
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ser_out_clk : out std_logic;
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ser_out_dat : out std_logic;
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ser_out_rclk : out std_logic;
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reset_c64 : in std_logic;
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reset_iec : in std_logic;
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ps2_mouse_clk : in std_logic;
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ps2_mouse_dat : in std_logic;
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ps2_keyboard_clk : in std_logic;
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ps2_keyboard_dat : in std_logic;
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led_green : in std_logic;
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led_red : in std_logic
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);
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end entity;
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architecture rtl of chameleon2_io_shiftreg is
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signal state_reg : unsigned(6 downto 0) := (others => '0');
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signal clk_reg : std_logic := '0';
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signal dat_reg : std_logic := '0';
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signal rclk_reg : std_logic := '1';
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begin
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ser_out_clk <= clk_reg;
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ser_out_dat <= dat_reg;
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ser_out_rclk <= rclk_reg;
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process(clk)
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begin
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if rising_edge(clk) then
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state_reg <= state_reg + 1;
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clk_reg <= state_reg(2) and (not state_reg(6));
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rclk_reg <= state_reg(2) and state_reg(6);
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case state_reg(6 downto 3) is
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when "0000" => dat_reg <= reset_c64;
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when "0001" => dat_reg <= reset_iec;
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when "0010" => dat_reg <= not ps2_mouse_clk;
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when "0011" => dat_reg <= not ps2_mouse_dat;
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when "0100" => dat_reg <= not ps2_keyboard_clk;
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when "0101" => dat_reg <= not ps2_keyboard_dat;
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when "0110" => dat_reg <= not led_green;
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when "0111" => dat_reg <= not led_red;
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when "1000" => null;
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when others => state_reg <= (others => '0');
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end case;
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end if;
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end process;
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end architecture;
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