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keyboard.vhd
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-- ZX Spectrum for Altera DE1
--
-- Copyright (c) 2009-2011 Mike Stirling
--
-- All rights reserved
--
-- Redistribution and use in source and synthezised forms, with or without
-- modification, are permitted provided that the following conditions are met:
--
-- * Redistributions of source code must retain the above copyright notice,
-- this list of conditions and the following disclaimer.
--
-- * Redistributions in synthesized form must reproduce the above copyright
-- notice, this list of conditions and the following disclaimer in the
-- documentation and/or other materials provided with the distribution.
--
-- * Neither the name of the author nor the names of other contributors may
-- be used to endorse or promote products derived from this software without
-- specific prior written agreement from the author.
--
-- * License is granted for non-commercial use only. A fee may not be charged
-- for redistributions as source code or in synthesized/hardware form without
-- specific prior written agreement from the author.
--
-- THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
-- AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
-- THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
-- PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE
-- LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
-- CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
-- SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
-- INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
-- CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
-- ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
-- POSSIBILITY OF SUCH DAMAGE.
--
-- PS/2 scancode to Spectrum matrix conversion
library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use IEEE.NUMERIC_STD.ALL;
entity keyboard is
port (
CLK : in std_logic;
nRESET : in std_logic;
-- PS/2 interface
PS2_CLK : in std_logic;
PS2_DATA : in std_logic;
-- CPU address bus (row)
A : in std_logic_vector(15 downto 0);
-- Column outputs to ULA
KEYB : out std_logic_vector(4 downto 0)
);
end keyboard;
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 (7 downto 0) of std_logic_vector(4 downto 0);
signal keys : key_matrix;
signal release : std_logic;
signal extended : std_logic;
begin
ps2 : ps2_intf port map (
CLK, nRESET,
PS2_CLK, PS2_DATA,
keyb_data, keyb_valid, keyb_error
);
-- Output addressed row to ULA
KEYB <= keys(0) when A(8) = '0' else
keys(1) when A(9) = '0' else
keys(2) when A(10) = '0' else
keys(3) when A(11) = '0' else
keys(4) when A(12) = '0' else
keys(5) when A(13) = '0' else
keys(6) when A(14) = '0' else
keys(7) when A(15) = '0' else
(others => '1');
process(nRESET,CLK)
begin
if nRESET = '0' then
release <= '0';
extended <= '0';
keys(0) <= (others => '1');
keys(1) <= (others => '1');
keys(2) <= (others => '1');
keys(3) <= (others => '1');
keys(4) <= (others => '1');
keys(5) <= (others => '1');
keys(6) <= (others => '1');
keys(7) <= (others => '1');
elsif rising_edge(CLK) then
if keyb_valid = '1' then
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';
case keyb_data is
when X"12" => keys(0)(0) <= release; -- Left shift (CAPS SHIFT)
when X"59" => keys(0)(0) <= release; -- Right shift (CAPS SHIFT)
when X"1a" => keys(0)(1) <= release; -- Z
when X"22" => keys(0)(2) <= release; -- X
when X"21" => keys(0)(3) <= release; -- C
when X"2a" => keys(0)(4) <= release; -- V
when X"1c" => keys(1)(0) <= release; -- A
when X"1b" => keys(1)(1) <= release; -- S
when X"23" => keys(1)(2) <= release; -- D
when X"2b" => keys(1)(3) <= release; -- F
when X"34" => keys(1)(4) <= release; -- G
when X"15" => keys(2)(0) <= release; -- Q
when X"1d" => keys(2)(1) <= release; -- W
when X"24" => keys(2)(2) <= release; -- E
when X"2d" => keys(2)(3) <= release; -- R
when X"2c" => keys(2)(4) <= release; -- T
when X"16" => keys(3)(0) <= release; -- 1
when X"1e" => keys(3)(1) <= release; -- 2
when X"26" => keys(3)(2) <= release; -- 3
when X"25" => keys(3)(3) <= release; -- 4
when X"2e" => keys(3)(4) <= release; -- 5
when X"45" => keys(4)(0) <= release; -- 0
when X"46" => keys(4)(1) <= release; -- 9
when X"3e" => keys(4)(2) <= release; -- 8
when X"3d" => keys(4)(3) <= release; -- 7
when X"36" => keys(4)(4) <= release; -- 6
when X"4d" => keys(5)(0) <= release; -- P
when X"44" => keys(5)(1) <= release; -- O
when X"43" => keys(5)(2) <= release; -- I
when X"3c" => keys(5)(3) <= release; -- U
when X"35" => keys(5)(4) <= release; -- Y
when X"5a" => keys(6)(0) <= release; -- ENTER
when X"4b" => keys(6)(1) <= release; -- L
when X"42" => keys(6)(2) <= release; -- K
when X"3b" => keys(6)(3) <= release; -- J
when X"33" => keys(6)(4) <= release; -- H
when X"29" => keys(7)(0) <= release; -- SPACE
when X"14" => keys(7)(1) <= release; -- CTRL (Symbol Shift)
when X"3a" => keys(7)(2) <= release; -- M
when X"31" => keys(7)(3) <= release; -- N
when X"32" => keys(7)(4) <= release; -- B
-- Cursor keys - these are actually extended (E0 xx), but
-- the scancodes for the numeric keypad cursor keys are
-- are the same but without the extension, so we'll accept
-- the codes whether they are extended or not
when X"6B" => keys(0)(0) <= release; -- Left (CAPS 5)
keys(3)(4) <= release;
when X"72" => keys(0)(0) <= release; -- Down (CAPS 6)
keys(4)(4) <= release;
when X"75" => keys(0)(0) <= release; -- Up (CAPS 7)
keys(4)(3) <= release;
when X"74" => keys(0)(0) <= release; -- Right (CAPS 8)
keys(4)(2) <= release;
-- Other special keys sent to the ULA as key combinations
when X"66" => keys(0)(0) <= release; -- Backspace (CAPS 0)
keys(4)(0) <= release;
when X"58" => keys(0)(0) <= release; -- Caps lock (CAPS 2)
keys(3)(1) <= release;
when X"76" => keys(0)(0) <= release; -- Escape (CAPS SPACE)
keys(7)(0) <= release;
when others =>
null;
end case;
end if;
end if;
end if;
end process;
end architecture;