diff options
Diffstat (limited to 'keyboard.vhd')
| -rw-r--r-- | keyboard.vhd | 251 |
1 files changed, 251 insertions, 0 deletions
diff --git a/keyboard.vhd b/keyboard.vhd new file mode 100644 index 0000000..0558469 --- /dev/null +++ b/keyboard.vhd @@ -0,0 +1,251 @@ +-- BBC keyboard implementation with interface to PS/2
+--
+-- (C) 2011 Mike Stirling
+--
+
+library IEEE;
+use IEEE.STD_LOGIC_1164.ALL;
+use IEEE.NUMERIC_STD.ALL;
+
+entity keyboard is
+port (
+ CLOCK : in std_logic;
+ nRESET : in std_logic;
+ CLKEN_1MHZ : in std_logic;
+
+ -- PS/2 interface
+ PS2_CLK : in std_logic;
+ PS2_DATA : in std_logic;
+
+ -- If 1 then column is incremented automatically at
+ -- 1 MHz rate
+ AUTOSCAN : in std_logic;
+
+ COLUMN : in std_logic_vector(3 downto 0);
+ ROW : in std_logic_vector(2 downto 0);
+
+ -- 1 when currently selected key is down (AUTOSCAN disabled)
+ KEYPRESS : out std_logic;
+ -- 1 when any key is down (except row 0)
+ INT : out std_logic;
+ -- BREAK key output - 1 when pressed
+ BREAK_OUT : out std_logic;
+
+ -- DIP switch inputs
+ DIP_SWITCH : in std_logic_vector(7 downto 0)
+ );
+end entity;
+
+architecture rtl of keyboard is
+
+-- PS/2 interface
+component ps2_intf is
+generic (filter_length : positive := 8);
+port(
+ CLK : in std_logic;
+ nRESET : in std_logic;
+
+ -- PS/2 interface (could be bi-dir)
+ PS2_CLK : in std_logic;
+ PS2_DATA : in std_logic;
+
+ -- Byte-wide data interface - only valid for one clock
+ -- so must be latched externally if required
+ DATA : out std_logic_vector(7 downto 0);
+ VALID : out std_logic;
+ ERROR : out std_logic
+ );
+end component;
+
+-- Interface to PS/2 block
+signal keyb_data : std_logic_vector(7 downto 0);
+signal keyb_valid : std_logic;
+signal keyb_error : std_logic;
+
+-- Internal signals
+type key_matrix is array(0 to 9) of std_logic_vector(7 downto 0);
+signal keys : key_matrix;
+signal col : unsigned(3 downto 0);
+signal release : std_logic;
+signal extended : std_logic;
+begin
+
+ ps2 : ps2_intf port map (
+ CLOCK, nRESET,
+ PS2_CLK, PS2_DATA,
+ keyb_data, keyb_valid, keyb_error
+ );
+
+ -- Column counts automatically when AUTOSCAN is enabled, otherwise
+ -- value is loaded from external input
+ process(CLOCK,nRESET)
+ begin
+ if nRESET = '0' then
+ col <= (others => '0');
+ elsif rising_edge(CLOCK) then
+ if AUTOSCAN = '0' then
+ -- If autoscan disabled then transfer current COLUMN to counter
+ -- immediately (don't wait for next 1 MHz cycle)
+ col <= unsigned(COLUMN);
+ elsif CLKEN_1MHZ = '1' then
+ -- Otherwise increment the counter once per 1 MHz tick
+ col <= col + 1;
+ end if;
+ end if;
+ end process;
+
+ -- Generate interrupt if any key in currently scanned column is pressed
+ -- (apart from in row 0). Output selected key status if autoscan disabled.
+ process(keys,col,ROW,AUTOSCAN)
+ variable k : std_logic_vector(7 downto 0);
+ begin
+ -- Shortcut to current key column
+ k := keys(to_integer(col));
+
+ -- Interrupt if any key pressed in rows 1 to 7.
+ INT <= k(7) or k(6) or k(5) or k(4) or k(3) or k(2) or k(1);
+
+ -- Determine which key is pressed
+ -- Inhibit output during auto-scan
+ if AUTOSCAN = '0' then
+ KEYPRESS <= k(to_integer(unsigned(ROW)));
+ else
+ KEYPRESS <= '0';
+ end if;
+ end process;
+
+ -- Decode PS/2 data
+ process(CLOCK,nRESET)
+ begin
+ if nRESET = '0' then
+ release <= '0';
+ extended <= '0';
+
+ BREAK_OUT <= '0';
+
+ keys(0) <= (others => '0');
+ keys(1) <= (others => '0');
+ keys(2) <= (others => '0');
+ keys(3) <= (others => '0');
+ keys(4) <= (others => '0');
+ keys(5) <= (others => '0');
+ keys(6) <= (others => '0');
+ keys(7) <= (others => '0');
+ keys(8) <= (others => '0');
+ keys(9) <= (others => '0');
+ elsif rising_edge(CLOCK) then
+ -- Copy DIP switches through to row 0
+ keys(2)(0) <= DIP_SWITCH(7);
+ keys(3)(0) <= DIP_SWITCH(6);
+ keys(4)(0) <= DIP_SWITCH(5);
+ keys(5)(0) <= DIP_SWITCH(4);
+ keys(6)(0) <= DIP_SWITCH(3);
+ keys(7)(0) <= DIP_SWITCH(2);
+ keys(8)(0) <= DIP_SWITCH(1);
+ keys(9)(0) <= DIP_SWITCH(0);
+
+ if keyb_valid = '1' then
+ -- Decode keyboard input
+ if keyb_data = X"e0" then
+ -- Extended key code follows
+ extended <= '1';
+ elsif keyb_data = X"f0" then
+ -- Release code follows
+ release <= '1';
+ else
+ -- Cancel extended/release flags for next time
+ release <= '0';
+ extended <= '0';
+
+ -- Decode scan codes
+ case keyb_data is
+ when X"12" => keys(0)(0) <= not release; -- Left SHIFT
+ when X"59" => keys(0)(0) <= not release; -- Right SHIFT
+ when X"15" => keys(0)(1) <= not release; -- Q
+ when X"09" => keys(0)(2) <= not release; -- F10 (F0)
+ when X"16" => keys(0)(3) <= not release; -- 1
+ when X"58" => keys(0)(4) <= not release; -- CAPS LOCK
+ when X"11" => keys(0)(5) <= not release; -- LEFT ALT (SHIFT LOCK)
+ when X"0D" => keys(0)(6) <= not release; -- TAB
+ when X"76" => keys(0)(7) <= not release; -- ESCAPE
+ when X"14" => keys(1)(0) <= not release; -- LEFT/RIGHT CTRL (CTRL)
+ when X"26" => keys(1)(1) <= not release; -- 3
+ when X"1D" => keys(1)(2) <= not release; -- W
+ when X"1E" => keys(1)(3) <= not release; -- 2
+ when X"1C" => keys(1)(4) <= not release; -- A
+ when X"1B" => keys(1)(5) <= not release; -- S
+ when X"1A" => keys(1)(6) <= not release; -- Z
+ when X"05" => keys(1)(7) <= not release; -- F1
+ when X"25" => keys(2)(1) <= not release; -- 4
+ when X"24" => keys(2)(2) <= not release; -- E
+ when X"23" => keys(2)(3) <= not release; -- D
+ when X"22" => keys(2)(4) <= not release; -- X
+ when X"21" => keys(2)(5) <= not release; -- C
+ when X"29" => keys(2)(6) <= not release; -- SPACE
+ when X"06" => keys(2)(7) <= not release; -- F2
+ when X"2E" => keys(3)(1) <= not release; -- 5
+ when X"2C" => keys(3)(2) <= not release; -- T
+ when X"2D" => keys(3)(3) <= not release; -- R
+ when X"2B" => keys(3)(4) <= not release; -- F
+ when X"34" => keys(3)(5) <= not release; -- G
+ when X"2A" => keys(3)(6) <= not release; -- V
+ when X"04" => keys(3)(7) <= not release; -- F3
+ when X"0C" => keys(4)(1) <= not release; -- F4
+ when X"3D" => keys(4)(2) <= not release; -- 7
+ when X"36" => keys(4)(3) <= not release; -- 6
+ when X"35" => keys(4)(4) <= not release; -- Y
+ when X"33" => keys(4)(5) <= not release; -- H
+ when X"32" => keys(4)(6) <= not release; -- B
+ when X"03" => keys(4)(7) <= not release; -- F5
+ when X"3E" => keys(5)(1) <= not release; -- 8
+ when X"43" => keys(5)(2) <= not release; -- I
+ when X"3C" => keys(5)(3) <= not release; -- U
+ when X"3B" => keys(5)(4) <= not release; -- J
+ when X"31" => keys(5)(5) <= not release; -- N
+ when X"3A" => keys(5)(6) <= not release; -- M
+ when X"0B" => keys(5)(7) <= not release; -- F6
+ when X"83" => keys(6)(1) <= not release; -- F7
+ when X"46" => keys(6)(2) <= not release; -- 9
+ when X"44" => keys(6)(3) <= not release; -- O
+ when X"42" => keys(6)(4) <= not release; -- K
+ when X"4B" => keys(6)(5) <= not release; -- L
+ when X"41" => keys(6)(6) <= not release; -- ,
+ when X"0A" => keys(6)(7) <= not release; -- F8
+ when X"4E" => keys(7)(1) <= not release; -- -
+ when X"45" => keys(7)(2) <= not release; -- 0
+ when X"4D" => keys(7)(3) <= not release; -- P
+ when X"0E" => keys(7)(4) <= not release; -- ` (@)
+ when X"4C" => keys(7)(5) <= not release; -- ;
+ when X"49" => keys(7)(6) <= not release; -- .
+ when X"01" => keys(7)(7) <= not release; -- F9
+ when X"55" => keys(8)(1) <= not release; -- = (^)
+ when X"5D" => keys(8)(2) <= not release; -- # (_)
+ when X"54" => keys(8)(3) <= not release; -- [
+ when X"52" => keys(8)(4) <= not release; -- '
+ when X"5B" => keys(8)(5) <= not release; -- ]
+ when X"4A" => keys(8)(6) <= not release; -- /
+ when X"61" => keys(8)(7) <= not release; -- \
+ when X"6B" => keys(9)(1) <= not release; -- LEFT
+ when X"72" => keys(9)(2) <= not release; -- DOWN
+ when X"75" => keys(9)(3) <= not release; -- UP
+ when X"5A" => keys(9)(4) <= not release; -- RETURN
+ when X"66" => keys(9)(5) <= not release; -- BACKSPACE (DELETE)
+ when X"69" => keys(9)(6) <= not release; -- END (COPY)
+ when X"74" => keys(9)(7) <= not release; -- RIGHT
+
+ -- F12 is used for the BREAK key, which in the real BBC asserts
+ -- reset. Here we pass this out to the top level which may
+ -- optionally OR it in to the system reset
+ when X"07" => BREAK_OUT <= not release; -- F12 (BREAK)
+
+ when others => null;
+ end case;
+
+ end if;
+ end if;
+ end if;
+ end process;
+
+end architecture;
+
+
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