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Line 81... |
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--##############################################################################
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--##############################################################################
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--
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--
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-- CPU access to hex display (unused by Altair SW)
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-- CPU access to hex display
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signal reg_display : std_logic_vector(15 downto 0);
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signal reg_display : std_logic_vector(15 downto 0);
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--##############################################################################
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--##############################################################################
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-- DE-1 board interface signals
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-- DE-1 board interface signals
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-- Synchronization FF chain for asynchronous reset input
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signal reset_sync : std_logic_vector(2 downto 0);
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-- Quad 7-segment display (non multiplexed) & LEDS
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-- Quad 7-segment display (non multiplexed) & LEDS
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signal display_data : std_logic_vector(15 downto 0);
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signal display_data : std_logic_vector(15 downto 0);
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signal reg_gleds : std_logic_vector(7 downto 0);
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signal reg_gleds : std_logic_vector(7 downto 0);
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-- i/o signals
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signal data_io_in : std_logic_vector(7 downto 0);
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signal data_mem_in : std_logic_vector(7 downto 0);
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signal data_rom_in : std_logic_vector(7 downto 0);
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signal rom_access : std_logic;
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signal rom_space : std_logic;
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signal breakpoint : std_logic;
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-- Clock & reset signals
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-- Clock & reset signals
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signal clk_1hz : std_logic;
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signal clk_1hz : std_logic;
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signal clk_master : std_logic;
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signal clk_master : std_logic;
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signal counter_1hz : std_logic_vector(25 downto 0);
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signal counter_1hz : std_logic_vector(25 downto 0);
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signal reset : std_logic;
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signal reset : std_logic;
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Line 127... |
signal mpu_sram_address : std_logic_vector(SRAM_ADDR_SIZE downto 1);
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signal mpu_sram_address : std_logic_vector(SRAM_ADDR_SIZE downto 1);
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signal mpu_sram_databus : std_logic_vector(15 downto 0);
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signal mpu_sram_databus : std_logic_vector(15 downto 0);
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signal mpu_sram_byte_we_n : std_logic_vector(1 downto 0);
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signal mpu_sram_byte_we_n : std_logic_vector(1 downto 0);
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signal mpu_sram_oe_n : std_logic;
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signal mpu_sram_oe_n : std_logic;
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-- Converts hex nibble to 7-segment
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-- Segments ordered as "GFEDCBA"; '0' is ON, '1' is OFF
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function nibble_to_7seg(nibble : std_logic_vector(3 downto 0))
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return std_logic_vector is
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begin
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case nibble is
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when X"0" => return "0000001";
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when X"1" => return "1001111";
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when X"2" => return "0010010";
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when X"3" => return "0000110";
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when X"4" => return "1001100";
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when X"5" => return "0100100";
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when X"6" => return "0100000";
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when X"7" => return "0001111";
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when X"8" => return "0000000";
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when X"9" => return "0000100";
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when X"a" => return "0001000";
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when X"b" => return "1100000";
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when X"c" => return "0110001";
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when X"d" => return "1000010";
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when X"e" => return "0110000";
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when X"f" => return "0111000";
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when others => return "0111111"; -- can't happen
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end case;
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end function nibble_to_7seg;
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begin
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begin
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mpu: entity work.mips_mpu
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mpu: entity work.mips_mpu
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Line 235... |
--##############################################################################
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--##############################################################################
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-- RESET, CLOCK
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-- RESET, CLOCK
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--##############################################################################
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--##############################################################################
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-- Use button 3 as reset
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-- Use button 3 as reset
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reset <= not buttons(3);
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reset_synchronization:
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process(clk)
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begin
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if clk'event and clk='1' then
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reset_sync(2) <= not buttons(3);
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reset_sync(1) <= reset_sync(2);
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reset_sync(0) <= reset_sync(1);
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end if;
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end process reset_synchronization;
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reset <= reset_sync(0);
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-- Generate a 1-Hz 'clock' to flash a LED for visual reference.
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-- Generate a 1-Hz 'clock' to flash a LED for visual reference.
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process(clk_50MHz)
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process(clk_50MHz)
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begin
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begin
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Line 282... |
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--##############################################################################
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--##############################################################################
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-- QUAD 7-SEGMENT DISPLAYS
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-- QUAD 7-SEGMENT DISPLAYS
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--##############################################################################
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--##############################################################################
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-- So far, nothing to display
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-- Show contents of debug register in hex display
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display_data <= reg_display;
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display_data <= reg_display;
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-- 7-segment encoders; the dev board displays are not multiplexed or encoded
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-- 7-segment encoders; the dev board displays are not multiplexed or encoded
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with display_data(15 downto 12) select hex3 <=
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hex3 <= nibble_to_7seg(display_data(15 downto 12));
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"0000001" when X"0","1001111" when X"1","0010010" when X"2","0000110" when X"3",
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hex2 <= nibble_to_7seg(display_data(11 downto 8));
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"1001100" when X"4","0100100" when X"5","0100000" when X"6","0001111" when X"7",
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hex1 <= nibble_to_7seg(display_data( 7 downto 4));
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"0000000" when X"8","0000100" when X"9","0001000" when X"a","1100000" when X"b",
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hex0 <= nibble_to_7seg(display_data( 3 downto 0));
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"0110001" when X"c","1000010" when X"d","0110000" when X"e","0111000" when others;
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with display_data(11 downto 8) select hex2 <=
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"0000001" when X"0","1001111" when X"1","0010010" when X"2","0000110" when X"3",
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"1001100" when X"4","0100100" when X"5","0100000" when X"6","0001111" when X"7",
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"0000000" when X"8","0000100" when X"9","0001000" when X"a","1100000" when X"b",
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"0110001" when X"c","1000010" when X"d","0110000" when X"e","0111000" when others;
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with display_data(7 downto 4) select hex1 <=
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"0000001" when X"0","1001111" when X"1","0010010" when X"2","0000110" when X"3",
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"1001100" when X"4","0100100" when X"5","0100000" when X"6","0001111" when X"7",
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"0000000" when X"8","0000100" when X"9","0001000" when X"a","1100000" when X"b",
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"0110001" when X"c","1000010" when X"d","0110000" when X"e","0111000" when others;
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with display_data(3 downto 0) select hex0 <=
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"0000001" when X"0","1001111" when X"1","0010010" when X"2","0000110" when X"3",
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"1001100" when X"4","0100100" when X"5","0100000" when X"6","0001111" when X"7",
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"0000000" when X"8","0000100" when X"9","0001000" when X"a","1100000" when X"b",
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"0110001" when X"c","1000010" when X"d","0110000" when X"e","0111000" when others;
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--##############################################################################
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--##############################################################################
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-- SD card interface
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-- SD card interface
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--##############################################################################
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--##############################################################################
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-- unused in this demo, but I did not bother to cut away the attached registers
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-- unused in this demo
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sd_cs <= '0';
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sd_cs <= '0';
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sd_cmd <= '0';
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sd_cmd <= '0';
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sd_clk <= '0';
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sd_clk <= '0';
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sd_in <= 'Z';
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sd_in <= 'Z';
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