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--                  

--                  

--  Dependencies   : ieee.std_logic_1164

--  Dependencies   : ieee.std_logic_1164

--                   ieee.std_logic_unsigned

--                   ieee.std_logic_unsigned

--                   ieee.std_logic_arith

--                   ieee.std_logic_arith

--                   ieee.numeric_std

--                   ieee.numeric_std

--

--

--  Author         : Original Verilog version by John Clayton

--  Author         : Original Verilog version by John Clayton

--                   Converted to VHDL by John E. Kent

--                   Converted to VHDL by John E. Kent

--

--

--  Email          : dilbert57@opencores.org      

--  Email          : dilbert57@opencores.org      

-- 2004-10-18 Added ctrl keys to ASCII ROM

-- 2004-10-18 Added ctrl keys to ASCII ROM

--            Added CAPS Lock toggle.

--            Added CAPS Lock toggle.

-- 2007-02-06 Added Generic Clock parameter

-- 2007-02-06 Added Generic Clock parameter

-- 2010-05-31 Revised header, added GPL

-- 2010-05-31 Revised header, added GPL

-- 2010-06-17 Change some signal names for consistancy

-- 2010-06-17 Change some signal names for consistancy

--

--

--

--

---------------------------------------------------------------------------------------

---------------------------------------------------------------------------------------

library ieee;

library ieee;

   use ieee.std_logic_1164.all;

   use ieee.std_logic_1164.all;

   use ieee.std_logic_arith.all;

   use ieee.std_logic_arith.all;

   use ieee.std_logic_unsigned.all;

   use ieee.std_logic_unsigned.all;

   use ieee.numeric_std.all;

   use ieee.numeric_std.all;

entity ps2_keyboard is

entity ps2_keyboard is

  generic (

  generic (

  CLK_FREQ_MHZ   : integer

  CLK_FREQ_MHZ   : integer

  );

  );

constant EXTEND_CODE  : integer := 16#E0#;

constant EXTEND_CODE  : integer := 16#E0#;

constant RELEASE_CODE : integer := 16#F0#;

constant RELEASE_CODE : integer := 16#F0#;

constant LEFT_SHIFT   : integer := 16#12#;

constant LEFT_SHIFT   : integer := 16#12#;

constant RIGHT_SHIFT  : integer := 16#59#;

constant RIGHT_SHIFT  : integer := 16#59#;

constant CTRL_CODE    : integer := 16#14#;

constant CTRL_CODE    : integer := 16#14#;

constant CAPS_CODE    : integer := 16#58#;

constant CAPS_CODE    : integer := 16#58#;

-- constants

-- constants

-- The timer value can be up to (2^bits) inclusive.

-- The timer value can be up to (2^bits) inclusive.

--constant TIMER_60USEC_BITS_PP  : integer := 11;   -- Number of bits needed for timer

--constant TIMER_60USEC_BITS_PP  : integer := 11;   -- Number of bits needed for timer

--constant TIMER_5USEC_VALUE_PP  : integer := 125;  -- Number of sys_clks for debounce

--constant TIMER_5USEC_VALUE_PP  : integer := 125;  -- Number of sys_clks for debounce

--constant TIMER_5USEC_BITS_PP   : integer := 7;    -- Number of bits needed for timer

--constant TIMER_5USEC_BITS_PP   : integer := 7;    -- Number of bits needed for timer

-- Values for  generic Clock up to 50 MHz

-- Values for  generic Clock up to 50 MHz

constant TIMER_60USEC_BITS_PP  : integer := 12;                 -- Number of bits needed for timer

constant TIMER_60USEC_BITS_PP  : integer := 12;                 -- Number of bits needed for timer

constant TIMER_5USEC_BITS_PP   : integer := 8;                  -- Number of bits needed for timer

constant TIMER_5USEC_BITS_PP   : integer := 8;                  -- Number of bits needed for timer

constant TRAP_SHIFT_KEYS_PP    : integer := 1;   -- Default: No shift key trap.

constant TRAP_SHIFT_KEYS_PP    : integer := 1;   -- Default: No shift key trap.

-- State encodings, provided as constants

-- State encodings, provided as constants

  tx_error                 <= '0';

  tx_error                 <= '0';

  enable_timer_60usec      <= '0';

  enable_timer_60usec      <= '0';

  enable_timer_5usec       <= '0';

  enable_timer_5usec       <= '0';

  case (m1_state) is

  case (m1_state) is

  when m1_rx_clk_h =>

  when m1_rx_clk_h =>

        enable_timer_60usec <= '1';

        enable_timer_60usec <= '1';

        if (tx_write = '1') then

        if (tx_write = '1') then

                      m1_next_state <= m1_tx_reset_timer;

                      m1_next_state <= m1_tx_reset_timer;

        elsif (ps2_clk_s = '0') then

        elsif (ps2_clk_s = '0') then

  when m1_rx_rising_edge_marker =>

  when m1_rx_rising_edge_marker =>

        enable_timer_60usec <= '0';

        enable_timer_60usec <= '0';

        m1_next_state <= m1_rx_clk_h;

        m1_next_state <= m1_rx_clk_h;

  when m1_tx_reset_timer =>

  when m1_tx_reset_timer =>

        enable_timer_60usec <= '0';

        enable_timer_60usec <= '0';

        m1_next_state <= m1_tx_force_clk_l;

        m1_next_state <= m1_tx_force_clk_l;

  when m1_tx_force_clk_l =>

  when m1_tx_force_clk_l =>

  when others =>

  when others =>

             m1_next_state <= m1_rx_clk_h;

             m1_next_state <= m1_rx_clk_h;

  end case;

  end case;

end process;

end process;

-- This is the bit counter

-- This is the bit counter

bit_counter: process(clk, reset, m1_state, bit_count )

bit_counter: process(clk, reset, m1_state, bit_count )

begin

begin

  if clk'event and clk = '0' then

  if clk'event and clk = '0' then

       (m1_state = m1_tx_wait_keyboard_ack) then       -- After tx is done.

       (m1_state = m1_tx_wait_keyboard_ack) then       -- After tx is done.

       bit_count <= "0000";  -- normal reset

       bit_count <= "0000";  -- normal reset

    elsif (timer_60usec_done = '1' ) and

    elsif (timer_60usec_done = '1' ) and

          (m1_state = m1_rx_clk_h)      and

          (m1_state = m1_rx_clk_h)      and

          (ps2_clk_s = '1') then

          (ps2_clk_s = '1') then

    elsif (m1_state = m1_rx_falling_edge_marker) or  -- increment for rx

    elsif (m1_state = m1_rx_falling_edge_marker) or  -- increment for rx

          (m1_state = m1_tx_rising_edge_marker) then  -- increment for tx

          (m1_state = m1_tx_rising_edge_marker) then  -- increment for tx

       bit_count <= bit_count + 1;

       bit_count <= bit_count + 1;

    end if;

    end if;

  end if;

  end if;

  if (bit_count = TOTAL_BITS) then

  if (bit_count = TOTAL_BITS) then

     rx_shifting_done <= '1';

     rx_shifting_done <= '1';

  else

  else

     rx_shifting_done <= '0';

     rx_shifting_done <= '0';

  end if;

  end if;

  if (bit_count = (TOTAL_BITS-1)) then

  if (bit_count = (TOTAL_BITS-1)) then

     tx_shifting_done <= '1';

     tx_shifting_done <= '1';

  else

  else

     tx_shifting_done <= '0';

     tx_shifting_done <= '0';

  end if;

  end if;

-- This is the signal which enables loading of the shift register.

-- This is the signal which enables loading of the shift register.

-- It also indicates "ack" to the device writing to the transmitter.

-- It also indicates "ack" to the device writing to the transmitter.

  if ((tx_write = '1') and (m1_state = m1_rx_clk_h)) or

  if ((tx_write = '1') and (m1_state = m1_rx_clk_h)) or

     ((tx_write = '1') and (m1_state = m1_rx_clk_l)) then

     ((tx_write = '1') and (m1_state = m1_rx_clk_l)) then

     tx_data_empty_o <= '1';

     tx_data_empty_o <= '1';

  else

  else

     tx_data_empty_o <= '0';

     tx_data_empty_o <= '0';

  end if;

  end if;

  tx_data_empty <= tx_data_empty_o;

  tx_data_empty <= tx_data_empty_o;

end process;

end process;

-- This is the ODD parity bit for the transmitted word.

-- This is the ODD parity bit for the transmitted word.

-- assign tx_parity_bit = ~^tx_data;

-- assign tx_parity_bit = ~^tx_data;

--

--

tx_parity_bit <= not( tx_data(7) xor tx_data(6) xor tx_data(5) xor tx_data(4) xor

tx_parity_bit <= not( tx_data(7) xor tx_data(6) xor tx_data(5) xor tx_data(4) xor

                      tx_data(3) xor tx_data(2) xor tx_data(1) xor tx_data(0) );

                      tx_data(3) xor tx_data(2) xor tx_data(1) xor tx_data(0) );

  if clk'event and clk='0' then

  if clk'event and clk='0' then

    if (reset = '1') then

    if (reset = '1') then

    elsif (tx_data_empty_o = '1') then

    elsif (tx_data_empty_o = '1') then

            q <= "1" & tx_parity_bit & tx_data & "0";

            q <= "1" & tx_parity_bit & tx_data & "0";

    elsif ( (m1_state = m1_rx_falling_edge_marker)      or

    elsif ( (m1_state = m1_rx_falling_edge_marker)      or

            (m1_state = m1_tx_rising_edge_marker) ) then

            (m1_state = m1_tx_rising_edge_marker) ) then

       q <= ps2_data_s & q((TOTAL_BITS-1) downto 1);

       q <= ps2_data_s & q((TOTAL_BITS-1) downto 1);

    end if;

    end if;

  end if;

  end if;

end process;

end process;

-- This is the 60usec timer counter

-- This is the 60usec timer counter

timer60usec: process(clk, enable_timer_60usec, timer_60usec_count)

timer60usec: process(clk, enable_timer_60usec, timer_60usec_count)

begin

begin

  if clk'event and clk = '0' then

  if clk'event and clk = '0' then

    if (enable_timer_60usec = '0') then

    if (enable_timer_60usec = '0') then

            timer_60usec_count <= (others => '0');

            timer_60usec_count <= (others => '0');

  else

  else

    timer_60usec_done <= '0';

    timer_60usec_done <= '0';

  end if;

  end if;

end process;

end process;

-- This is the 5usec timer counter

-- This is the 5usec timer counter

timer5usec : process(clk, enable_timer_5usec, timer_5usec_count )

timer5usec : process(clk, enable_timer_5usec, timer_5usec_count )

begin

begin

  if clk'event and clk = '0' then

  if clk'event and clk = '0' then

    if (enable_timer_5usec = '0') then

    if (enable_timer_5usec = '0') then

           timer_5usec_count <= (others => '0');

           timer_5usec_count <= (others => '0');

  else

  else

         timer_5usec_done <= '0';

         timer_5usec_done <= '0';

  end if;

  end if;

end process;

end process;

-- Store the special scan code status bits

-- Store the special scan code status bits

-- Not the final output, but an intermediate storage place,

-- Not the final output, but an intermediate storage place,

-- until the entire set of output data can be assembled.

-- until the entire set of output data can be assembled.

special_scan : process(clk, reset, rx_output_event, rx_shifting_done, extended, released )

special_scan : process(clk, reset, rx_output_event, rx_shifting_done, extended, released )

begin

begin

  if clk'event and clk='0' then

  if clk'event and clk='0' then

    if (reset = '1') or (rx_output_event = '1') then

    if (reset = '1') or (rx_output_event = '1') then

      hold_extended <= '0';

      hold_extended <= '0';

      if (rx_shifting_done = '1') and (released = '1') then

      if (rx_shifting_done = '1') and (released = '1') then

             hold_released <= '1';

             hold_released <= '1';

      end if;

      end if;

    end if;

    end if;

  end if;

  end if;

end process;

end process;

-- These bits contain the status of the two shift keys

-- These bits contain the status of the two shift keys

left_shift_proc : process(clk, reset, q, rx_shifting_done, hold_released )

left_shift_proc : process(clk, reset, q, rx_shifting_done, hold_released )

begin

begin

  if clk'event and clk = '0' then

  if clk'event and clk = '0' then

    if (reset = '1') then

    if (reset = '1') then

           left_shift_key <= '0';

           left_shift_key <= '0';

    end if;

    end if;

  end if;

  end if;

end process;

end process;

right_shift_proc : process(clk, reset, q, rx_shifting_done, hold_released )

right_shift_proc : process(clk, reset, q, rx_shifting_done, hold_released )

begin

begin

  if clk'event and clk = '0' then

  if clk'event and clk = '0' then

    if (reset = '1') then

    if (reset = '1') then

           right_shift_key <= '0';

           right_shift_key <= '0';

    end if;

    end if;

  end if;

  end if;

end process;

end process;

shift_key_on <= left_shift_key or right_shift_key;

shift_key_on <= left_shift_key or right_shift_key;

rx_shift_on <= shift_key_on;

rx_shift_on <= shift_key_on;

--

--

-- Control keys

-- Control keys

--

--

ctrl_proc : process(clk, reset, q, rx_shifting_done, hold_released )

ctrl_proc : process(clk, reset, q, rx_shifting_done, hold_released )

begin

begin

  if clk'event and clk = '0' then

  if clk'event and clk = '0' then

    if (reset = '1') then

    if (reset = '1') then

           ctrl_key_on <= '0';

           ctrl_key_on <= '0';

    end if;

    end if;

  end if;

  end if;

end process;

end process;

--

--

caps_proc : process(clk, reset, q, rx_shifting_done, hold_released, caps_key_on )

caps_proc : process(clk, reset, q, rx_shifting_done, hold_released, caps_key_on )

begin

begin

  if clk'event and clk = '0' then

  if clk'event and clk = '0' then

    if (reset = '1') then

    if (reset = '1') then

           caps_key_on <= '0';

           caps_key_on <= '0';

      caps_key_on <= not caps_key_on;

      caps_key_on <= not caps_key_on;

    end if;

    end if;

  end if;

  end if;

end process;

end process;

-- Output the special scan code flags, the scan code and the ascii

-- Output the special scan code flags, the scan code and the ascii

                                                                         hold_extended, hold_released,

                                                                         hold_extended, hold_released,

begin

begin

  if clk'event and clk = '0' then

  if clk'event and clk = '0' then

    if (reset = '1')    then

    if (reset = '1')    then

      rx_extended <= '0';

      rx_extended <= '0';

      rx_released <= '0';

      rx_released <= '0';

    elsif (rx_output_strobe = '1') then

    elsif (rx_output_strobe = '1') then

      rx_extended <= hold_extended;

      rx_extended <= hold_extended;

      rx_released <= hold_released;

      rx_released <= hold_released;

           rx_data <= ascii and x"1f";

           rx_data <= ascii and x"1f";

    else

    else

      rx_data <= ascii;

      rx_data <= ascii;

    end if;

    end if;

  end if;

  end if;

end process;

end process;

-- Store the final rx output data only when all extend and release codes

-- Store the final rx output data only when all extend and release codes

-- are received and the next (actual key) scan code is also ready.

-- are received and the next (actual key) scan code is also ready.

-- (the presence of rx_extended or rx_released refers to the

-- (the presence of rx_extended or rx_released refers to the

-- the current latest scan code received, not the previously latched flags.)

-- the current latest scan code received, not the previously latched flags.)

rx_output_proc : process( clk, reset,

rx_output_proc : process( clk, reset,

                          rx_shifting_done, rx_output_strobe,

                          rx_shifting_done, rx_output_strobe,

                          extended, released,

                          extended, released,

                                                                  q, ascii, rx_read )

                                                                  q, ascii, rx_read )

begin

begin

  if clk'event and clk = '0' then

  if clk'event and clk = '0' then

    if reset = '1' then

    if reset = '1' then

           rx_output_strobe <= '0';

           rx_output_strobe <= '0';

                         (hold_released = '0' ) and

                         (hold_released = '0' ) and

--        ((TRAP_SHIFT_KEYS_PP = 0) or

--        ((TRAP_SHIFT_KEYS_PP = 0) or

--          ( (q(8 downto 1) /= RIGHT_SHIFT) and 

--          ( (q(8 downto 1) /= RIGHT_SHIFT) and 

--                 (q(8 downto 1) /= LEFT_SHIFT) and

--                 (q(8 downto 1) /= LEFT_SHIFT) and

--                      (q(8 downto 1) /= CTRL_CODE) ) )then

--                      (q(8 downto 1) /= CTRL_CODE) ) )then

      rx_output_strobe <= '1';

      rx_output_strobe <= '1';

    end if;

    end if;

  end if;

  end if;

  rx_data_ready <= rx_output_strobe;

  rx_data_ready <= rx_output_strobe;

end process;

end process;

-- This part translates the scan code into an ASCII value...

-- This part translates the scan code into an ASCII value...

-- Only the ASCII codes which I considered important have been included.

-- Only the ASCII codes which I considered important have been included.

-- if you want more, just add the appropriate case statement lines...

-- if you want more, just add the appropriate case statement lines...

-- (You will need to know the keyboard scan codes you wish to assign.)

-- (You will need to know the keyboard scan codes you wish to assign.)

-- The entries are listed in ascending order of ASCII value.

-- The entries are listed in ascending order of ASCII value.

--shift_map : process( shift_key_plus_code )

--shift_map : process( shift_key_plus_code )

--begin

--begin

--  case shift_key_plus_code is

--  case shift_key_plus_code is

--  when x"066" => ascii <= x"08";  -- Backspace ("backspace" key)

--  when x"066" => ascii <= x"08";  -- Backspace ("backspace" key)

--  when x"166" => ascii <= x"08";  -- Backspace ("backspace" key)

--  when x"166" => ascii <= x"08";  -- Backspace ("backspace" key)

--  when x"15d" => ascii <= x"7c";  -- |

--  when x"15d" => ascii <= x"7c";  -- |

--  when x"15b" => ascii <= x"7d";  -- }

--  when x"15b" => ascii <= x"7d";  -- }

--  when x"10e" => ascii <= x"7e";  -- ~

--  when x"10e" => ascii <= x"7e";  -- ~

--  when x"071" => ascii <= x"7f";  -- (Delete OR DEL on numeric keypad)

--  when x"071" => ascii <= x"7f";  -- (Delete OR DEL on numeric keypad)

--  when x"171" => ascii <= x"7f";  -- (Delete OR DEL on numeric keypad)

--  when x"171" => ascii <= x"7f";  -- (Delete OR DEL on numeric keypad)

--  end case;

--  end case;

--end process;

--end process;

end rtl;

end rtl;

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