ps2_keyboard_interface.vhd

BurchED B5-X300 Spartan2e using XC2S300e device Top level file for 6809 compatible system on a chi

  end if;
end process;

-- This is the 60usec timer counter
timer60usec: process(clk, enable_timer_60usec, timer_60usec_count)
begin
  if clk'event and clk = '1' then
    if (enable_timer_60usec = '0') then
	    timer_60usec_count <= "0000000000";
    elsif (timer_60usec_done = '0') then
	    timer_60usec_count <= timer_60usec_count + 1;
    end if;
  end if;

  if (timer_60usec_count = (TIMER_60USEC_VALUE_PP - 1)) then
	 timer_60usec_done <= '1';
  else
    timer_60usec_done <= '0';
  end if;
end process;

-- This is the 5usec timer counter
timer5usec : process(clk, enable_timer_5usec, timer_5usec_count )
begin
  if clk'event and clk = '1' then
    if (enable_timer_5usec = '0') then
	   timer_5usec_count <= "000000";
    elsif (timer_5usec_done = '0') then
	   timer_5usec_count <= timer_5usec_count + 1;
    end if;
  end if;

  if( timer_5usec_count = (TIMER_5USEC_VALUE_PP - 1)) then
	 timer_5usec_done <= '1';
  else
	 timer_5usec_done <= '0';
  end if;
end process;


-- Store the special scan code status bits
-- Not the final output, but an intermediate storage place,
-- until the entire set of output data can be assembled.
special_scan : process(clk, reset, rx_output_event, rx_shifting_done, extended, released )
begin
  if clk'event and clk='1' then
    if (reset = '1') or (rx_output_event = '1')	then
      hold_extended <= '0';
      hold_released <= '0';
    else
      if (rx_shifting_done = '1') and (extended = '1') then
	     hold_extended <= '1';
      end if;
      if (rx_shifting_done = '1') and (released = '1') then
	     hold_released <= '1';
      end if;
    end	if;
  end if;
end process;


-- These bits contain the status of the two shift keys
left_shift_proc : process(clk, reset, q, rx_shifting_done, hold_released )
begin
  if clk'event and clk = '1' then
    if (reset = '1') then
	   left_shift_key <= '0';
    elsif (q(8 downto 1) = LEFT_SHIFT) and 
	       (rx_shifting_done = '1') and 
			 (hold_released = '0') then
      left_shift_key <= '1';
    elsif (q(8 downto 1) = LEFT_SHIFT) and
	       (rx_shifting_done = '1') and
			 (hold_released = '1') then
      left_shift_key <= '0';
    end if;
  end if;
end process;

right_shift_proc : process(clk, reset, q, rx_shifting_done, hold_released )
begin
  if clk'event and clk = '1' then
    if (reset = '1') then
	   right_shift_key <= '0';
    elsif (q(8 downto 1) = RIGHT_SHIFT) and
	       (rx_shifting_done = '1') and
			 (hold_released = '0') then
      right_shift_key <= '1';
    elsif (q(8 downto 1) = RIGHT_SHIFT) and
	       (rx_shifting_done = '1') and
			 (hold_released = '1') then
      right_shift_key <= '0';
    end if;
  end if;
end process;

shift_key_on <= left_shift_key or right_shift_key;
rx_shift_key_on <= shift_key_on;

-- Output the special scan code flags, the scan code and the ascii
special_scan_proc : process(clk, reset, hold_extended, hold_released, q, ascii )
begin
  if clk'event and clk = '1' then
    if (reset = '1')	then
      rx_extended <= '0';
      rx_released <= '0';
--      rx_scan_code <= "00000000";
      rx_ascii <= "00000000";
    elsif (rx_output_strobe = '1') then
      rx_extended <= hold_extended;
      rx_released <= hold_released;
--      rx_scan_code <= q(8 downto 1);
      rx_ascii <= ascii;
    end if;
  end if;
end process;

-- 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.
-- (the presence of rx_extended or rx_released refers to the
-- the current latest scan code received, not the previously latched flags.)

rx_output_proc : process( rx_shifting_done, extended, released, q )
begin
  if (rx_shifting_done = '1') and (extended = '0') and (released = '0') then
    rx_output_event <= '1';
  else
    rx_output_event <= '0';
  end if;

  if (rx_shifting_done = '1') and (extended = '0') and (released = '0') and
     ( (TRAP_SHIFT_KEYS_PP = 0) or
	    ( (q(8 downto 1) /= RIGHT_SHIFT)	and (q(8 downto 1) /= LEFT_SHIFT) ) )then
    rx_output_strobe <= '1';
  else
    rx_output_strobe <= '0';
  end if;      
end process;


-- This part translates the scan code into an ASCII value...
-- Only the ASCII codes which I considered important have been included.
-- if you want more, just add the appropriate case statement lines...
-- (You will need to know the keyboard scan codes you wish to assign.)
-- The entries are listed in ascending order of ASCII value.
shift_key_plus_code <= "000" & shift_key_on & q(8 downto 1);

shift_map : process( shift_key_plus_code )
begin
  case (shift_key_plus_code) is
  when x"066" => ascii <= x"08";  -- Backspace ("backspace" key)
  when x"166" => ascii <= x"08";  -- Backspace ("backspace" key)
  when x"00d" => ascii <= x"09";  -- Horizontal Tab
  when x"10d" => ascii <= x"09";  -- Horizontal Tab
  when x"05a" => ascii <= x"0d";  -- Carriage return ("enter" key)
  when x"15a" => ascii <= x"0d";  -- Carriage return ("enter" key)
  when x"076" => ascii <= x"1b";  -- Escape ("esc" key)
  when x"176" => ascii <= x"1b";  -- Escape ("esc" key)
  when x"029" => ascii <= x"20";  -- Space
  when x"129" => ascii <= x"20";  -- Space
  when x"116" => ascii <= x"21";  -- !
  when x"152" => ascii <= x"22";  -- "
  when x"126" => ascii <= x"23";  -- #
  when x"125" => ascii <= x"24";  -- $
  when x"12e" => ascii <= x"25";  -- %
  when x"13d" => ascii <= x"26";  -- &
  when x"052" => ascii <= x"27";  -- '
  when x"146" => ascii <= x"28";  -- (
  when x"145" => ascii <= x"29";  -- )
  when x"13e" => ascii <= x"2a";  -- *
  when x"155" => ascii <= x"2b";  -- +
  when x"041" => ascii <= x"2c";  -- ,
  when x"04e" => ascii <= x"2d";  -- -
  when x"049" => ascii <= x"2e";  -- .
  when x"04a" => ascii <= x"2f";  -- /
  when x"045" => ascii <= x"30";  -- 0
  when x"016" => ascii <= x"31";  -- 1
  when x"01e" => ascii <= x"32";  -- 2
  when x"026" => ascii <= x"33";  -- 3
  when x"025" => ascii <= x"34";  -- 4
  when x"02e" => ascii <= x"35";  -- 5
  when x"036" => ascii <= x"36";  -- 6
  when x"03d" => ascii <= x"37";  -- 7
  when x"03e" => ascii <= x"38";  -- 8
  when x"046" => ascii <= x"39";  -- 9
  when x"14c" => ascii <= x"3a";  -- :
  when x"04c" => ascii <= x"3b";  -- ;
  when x"141" => ascii <= x"3c";  -- <
  when x"055" => ascii <= x"3d";  -- =
  when x"149" => ascii <= x"3e";  -- >
  when x"14a" => ascii <= x"3f";  -- ?
  when x"11e" => ascii <= x"40";  -- @
  when x"11c" => ascii <= x"41";  -- A
  when x"132" => ascii <= x"42";  -- B
  when x"121" => ascii <= x"43";  -- C
  when x"123" => ascii <= x"44";  -- D
  when x"124" => ascii <= x"45";  -- E
  when x"12b" => ascii <= x"46";  -- F
  when x"134" => ascii <= x"47";  -- G
  when x"133" => ascii <= x"48";  -- H
  when x"143" => ascii <= x"49";  -- I
  when x"13b" => ascii <= x"4a";  -- J
  when x"142" => ascii <= x"4b";  -- K
  when x"14b" => ascii <= x"4c";  -- L
  when x"13a" => ascii <= x"4d";  -- M
  when x"131" => ascii <= x"4e";  -- N
  when x"144" => ascii <= x"4f";  -- O
  when x"14d" => ascii <= x"50";  -- P
  when x"115" => ascii <= x"51";  -- Q
  when x"12d" => ascii <= x"52";  -- R
  when x"11b" => ascii <= x"53";  -- S
  when x"12c" => ascii <= x"54";  -- T
  when x"13c" => ascii <= x"55";  -- U
  when x"12a" => ascii <= x"56";  -- V
  when x"11d" => ascii <= x"57";  -- W
  when x"122" => ascii <= x"58";  -- X
  when x"135" => ascii <= x"59";  -- Y
  when x"11a" => ascii <= x"5a";  -- Z
  when x"054" => ascii <= x"5b";  -- [
  when x"05d" => ascii <= x"5c";  -- \
  when x"05b" => ascii <= x"5d";  -- ]
  when x"136" => ascii <= x"5e";  -- ^
  when x"14e" => ascii <= x"5f";  -- _    
  when x"00e" => ascii <= x"60";  -- `
  when x"01c" => ascii <= x"61";  -- a
  when x"032" => ascii <= x"62";  -- b
  when x"021" => ascii <= x"63";  -- c
  when x"023" => ascii <= x"64";  -- d
  when x"024" => ascii <= x"65";  -- e
  when x"02b" => ascii <= x"66";  -- f
  when x"034" => ascii <= x"67";  -- g
  when x"033" => ascii <= x"68";  -- h
  when x"043" => ascii <= x"69";  -- i
  when x"03b" => ascii <= x"6a";  -- j
  when x"042" => ascii <= x"6b";  -- k
  when x"04b" => ascii <= x"6c";  -- l
  when x"03a" => ascii <= x"6d";  -- m
  when x"031" => ascii <= x"6e";  -- n
  when x"044" => ascii <= x"6f";  -- o
  when x"04d" => ascii <= x"70";  -- p
  when x"015" => ascii <= x"71";  -- q
  when x"02d" => ascii <= x"72";  -- r
  when x"01b" => ascii <= x"73";  -- s
  when x"02c" => ascii <= x"74";  -- t
  when x"03c" => ascii <= x"75";  -- u
  when x"02a" => ascii <= x"76";  -- v
  when x"01d" => ascii <= x"77";  -- w
  when x"022" => ascii <= x"78";  -- x
  when x"035" => ascii <= x"79";  -- y
  when x"01a" => ascii <= x"7a";  -- z
  when x"154" => ascii <= x"7b";  -- {
  when x"15d" => ascii <= x"7c";  -- |
  when x"15b" => ascii <= x"7d";  -- }
  when x"10e" => ascii <= x"7e";  -- ~
  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 others => ascii <= x"2e";  -- '.' used for unlisted characters.
  end case;
end process;

end my_ps2_keyboard;