--
--
-- Keyboard module (provides exteranl inputs through PS2 Keyboard)
--
Library altera,IEEE,lpm;
use altera.maxplus2.all;
use IEEE.STD_LOGIC_1164.all;
USE lpm.lpm_components.ALL;
use IEEE.STD_LOGIC_ARITH.all;
use IEEE.STD_LOGIC_signed.all;
entity Keyboard is
Generic(DATA_LENGTH : integer := 9);
port( reset : in std_Logic;
Keyboard_DATA, Keyboard_CLOCK : in std_logic;
clock : in std_Logic;
parity_D,stopbit_D : out std_logic;
key_stroke : out std_logic;
k_data_D : out std_logic_vector(7 downto 0);
key_ascii_D : out std_logic_vector(7 downto 0));
end Keyboard;
--
-- Keyboard architecture
--
architecture behavioral of Keyboard is
signal k_data : std_logic_vector(DATA_LENGTH downto 0);
signal key_ascii : std_logic_vector(5 downto 0);
signal receive_key : std_logic := '0';
signal start,stop_getkey : std_logic := '0';
signal cnt : std_logic_vector(3 downto 0) := "0000";
signal filter : std_logic_vector(7 downto 0);
signal keyboard_clk_filt : std_logic;
signal parityok : std_logic := '0';
signal shift_key : std_logic := '0';
-- Function Defined to Check the parity of the input signal.
-- If the parity is correct, a '1' is returned else it is a '0';
function paritycheck(p_data : in std_logic_vector(8 downto 0)) return std_logic is
variable Result: std_logic :='0';
begin
xor_loop:
FOR N IN p_data'range LOOP
Result := Result xor p_data(N);
END LOOP xor_loop;
return Result;
end function paritycheck;
begin
process (start, clock, cnt)
variable cntclk : std_logic_vector(14 downto 0);
begin
wait until clock'event and clock = '1';
if start = '0' or cnt = "0000" then
cntclk := "000000000000000";
stop_getkey <= '0';
else
cntclk := cntclk + 1;
if cntclk = "100111010000100" then
stop_getkey <= '1';
end if;
end if;
end process;
process
begin
wait until clock'event and clock='0';
filter(6 downto 0) <= filter(7 downto 1);
filter(7) <= keyboard_clock;
if filter = "00000000" then keyboard_clk_filt <= '0';
else keyboard_clk_filt <= '1';
end if;
end process;
process
variable cnter : std_logic_vector(3 downto 0) := "0000";
begin
wait until keyboard_clk_filt'event and keyboard_clk_filt = '0';
if keyboard_data ='0' and start = '0' then --(start = '0' or stop_getkey = '1') then
start <= '1';
cnter := "0000";
k_data <= "0000000000";
else
if start = '1' then
cnter := cnter + 1;
case cnter(3 downto 0) is
when "0001" => k_data(0) <= Keyboard_DATA;
when "0010" => k_data(1) <= Keyboard_DATA;
when "0011" => k_data(2) <= Keyboard_DATA;
when "0100" => k_data(3) <= Keyboard_DATA;
when "0101" => k_data(4) <= Keyboard_DATA;
when "0110" => k_data(5) <= Keyboard_DATA;
when "0111" => k_data(6) <= Keyboard_DATA;
when "1000" => k_data(7) <= Keyboard_DATA;
when "1001" => k_data(8) <= Keyboard_DATA;
when others => k_data(9) <= Keyboard_DATA;
start <= '0';
receive_key <= not receive_key;
end case;
end if;
end if;
cnt <= cnter;
end process; -- keyboard clock process
scancode_rom: lpm_rom
GENERIC MAP ( lpm_widthad => 8,
lpm_numwords => "256",
lpm_outdata => "UNREGISTERED",
lpm_address_control => "UNREGISTERED",
-- Reads in mif file for character generator data
lpm_file => "scancode.mif",
lpm_width => 6)
PORT MAP ( --inclock => clock,
address => k_data(7 downto 0),
q => key_ascii);
parityok <= paritycheck(k_data(8 downto 0));
process
variable tmp_stroke, cur_key, break_code : std_logic := '0';
begin
wait until clock'event and clock ='1';
if reset = '1' then
key_ascii_D <= "00100000";
else
k_data_d <= k_data(7 downto 0);
if cur_key /= receive_key then
cur_key := receive_key;
parity_D <= parityok;
stopbit_D <= k_data(9);
if break_code = '0' then
if k_data(7 downto 0) = "11110000" then
break_code := '1';
else
--do we have a valid key?
--if k_data(9) = '1' and parityok = '1' then
-- stop bit and parity check out ok
-- the return, backspace, and shift keys all return key_ascii value
-- of "111111" since these characters are not mapped directly to the
-- tiny character generator ROM. Therefore, we assume (by default) that
-- any key_ascii value not "111111" is a valid mapped key.
if key_ascii /= "111111" then
key_ascii_D(7 downto 0) <= "00" & key_ascii(5 downto 0);
tmp_stroke := not tmp_stroke;
key_stroke <= tmp_stroke;
elsif k_data(7 downto 0) = "01011010" or -- return
k_data(7 downto 0) = "01100110" then --backspace
key_ascii_D(7 downto 0) <= k_data(6 downto 5) & "000000";
tmp_stroke := not tmp_stroke;
key_stroke <= tmp_stroke;
end if;
if k_data(7 downto 0) = "00010010" or --Left Shift
k_data(7 downto 0) = "01011001" then -- Right Shift
shift_key <= '1';
end if;
--end if; -- if k_data(9)
end if; -- if k_data(7 downto 0)
else
break_code := '0';
-- turn off shift during the break portion
if --k_data(9) = '1' and parityok = '1' and
(k_data(7 downto 0) = "00010010" or
k_data(7 downto 0) = "01011001") then
shift_key <= '0';
end if;
end if; -- if break_code
end if; -- if cur_key
end if; -- if reset
end process;
end behavioral;
<div align="center"><br /><script type="text/javascript"><!--
google_ad_client = "pub-7293844627074885";
//468x60, Created at 07. 11. 25
google_ad_slot = "8619794253";
google_ad_width = 468;
google_ad_height = 60;
//--></script>
<script type="text/javascript" src="http://pagead2.googlesyndication.com/pagead/show_ads.js">
</script><br /> </div>