PS2键盘时钟与系统时钟

shangwfa

1楼-- · 2019-07-16 06:11

没有任何关系，键盘的时钟是我们采集键盘数据输出的依据

yoonssica

2楼-- · 2019-07-16 11:19

shangwfa 发表于 2013-7-29 23:48
没有任何关系，键盘的时钟是我们采集键盘数据输出的依据

也就是说数据只与键盘的时钟有关，而与系统的是时钟无关？那系统时钟做什么用呢？

主宰自己

3楼-- · 2019-07-16 14:19

不用管他，板子上有，你直接在顶层模块输入键盘时钟就好了

yoonssica

4楼-- · 2019-07-16 19:05

主宰自己发表于 2013-7-30 12:32
不用管他，板子上有，你直接在顶层模块输入键盘时钟就好了

<DIV class=blockcode>
<BLOCKQUOTE>library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use IEEE.STD_LOGIC_ARITH.ALL;
use IEEE.STD_LOGIC_UNSIGNED.ALL;
entity ps2 is
port (resetn: in std_logic; -- active low reset
clock: in std_logic; -- system clock
ps2_clk: in std_logic; -- PS/2 clock line
ps2_dta: in std_logic; -- PS/2 data line
hit_1: out std_logic;
ascii: out std_logic_vector(7 downto 0)); -- LED outputs
end ps2;
architecture behavioral of ps2 is
type state_type is (IDLE, START, DATA, PARITY); -- FSM states
signal ps2_dv: std_logic; -- PS/2 data valid
signal prv_ps2_clk, act_ps2_clk: std_logic; -- auxiliary signals
signal recdata: std_logic_vector(7 downto 0); -- read data
signal shift: std_logic; -- enable for shift reg.
signal n_shift: std_logic; -- auxiliary signal
signal latch: std_logic; -- latch read data
signal n_latch: std_logic; -- auxiliary signal
signal err: std_logic; -- parity or stop error
signal n_err: std_logic; -- auxiliary signal
signal parset: std_logic; -- preset for parity check
signal n_parset: std_logic; -- auxiliary signal
signal c_state, n_state: state_type; -- current & next states
signal cntval: std_logic_vector(2 downto 0); -- counter of data bits
signal zero: std_logic; -- counter is zero
signal parbit: std_logic; -- odd parity of data
signal leds:std_logic_vector(7 downto 0);
signal hit_cnt:std_logic_vector(8 downto 0);
signal hit:std_logic;
begin
-- Provides a one-shot pulse after every falling edge of PS/2 clock
PS_CLK_SYNC: process(clock, resetn)
begin
if (resetn = '0') then
prv_ps2_clk <= '1';
act_ps2_clk <= '1';
elsif (clock'event and clock = '1') then
act_ps2_clk <= ps2_clk;
prv_ps2_clk <= act_ps2_clk;
end if;
end process;
ps2_dv <= (not act_ps2_clk) and prv_ps2_clk;
-- Serial input, parallel output shift register
SIPO: process(clock, resetn)
begin
if (resetn = '0') then
recdata <= (others => '0');
elsif (clock'event and clock = '1') then
if (shift = '1') then
recdata <= ps2_dta & recdata(7 downto 1);
end if;
end if;
end process;
-- Counter of data bits
COUNT8: process(resetn, clock)
begin
if (resetn = '0') then
cntval <= (others => '0');
elsif (clock'event and clock = '1') then
if (shift = '1') then
cntval <= cntval + 1;
end if;
end if;
end process;
zero <= not (cntval(0) or cntval(1) or cntval(2));
-- Parity check of received data
PARITY_CHECK: process(clock, parset)
begin
if (parset = '1') then
parbit <= '1';
elsif (clock'event and clock = '1') then
if (shift = '1' and ps2_dta = '1') then
parbit <= not parbit;
end if;
end if;
end process;
-- Synchronous process of control state machine
FSM_SYNC: process(clock, resetn)
begin
if (resetn = '0') then
c_state <= IDLE;
shift <= '0';
latch <= '0';
err <= '0';
parset <= '1';
elsif (clock'event and clock = '1') then
c_state <= n_state;
shift <= n_shift;
latch <= n_latch;
err <= n_err;
parset <= n_parset;
end if;
end process;
-- Combinatorial process of control state machine
FSM_COMB: process(c_state, ps2_dv, ps2_dta, zero)
begin -- default values
n_shift <= '0';
n_latch <= '0';
n_err <= '0';
n_parset <= '0';
case c_state is -- wait to receive data
when IDLE => if ((ps2_dv and (not ps2_dta)) = '1') then
n_state <= START;
n_parset <= '1';
else
n_state <= IDLE;
end if;
-- receive first data bit
when START => if (ps2_dv = '0') then
n_state <= START;
else
n_state <= DATA;
n_shift <= '1';
end if;
-- receive remaining data bits and parity
when DATA => if (ps2_dv = '0') then
n_state <= DATA;
elsif (zero = '0') then
n_state <= DATA;
n_shift <= '1';
else
n_state <= PARITY;
if (parbit /= ps2_dta) then
n_err <= '1';
end if;
end if;
-- receive stop bit
when PARITY => if (ps2_dv = '0') then
n_state <= PARITY;
else
n_state <= IDLE;
n_latch <= '1';
n_err <= not ps2_dta;
end if;
end case;
end process;
-- Output latch
LED_OUTPUTS: process(resetn, clock)
begin
if (resetn = '0') then
leds <= (others => '1');
elsif (clock'event and clock = '1') then
if (err = '1') then
leds <= (others => '1');
elsif (latch = '1') then
leds <= recdata;
end if;
end if;
end process;
PROCESS(leds)
BEGIN
case leds is
when "01000101"=> ascii <= "00110000"; hit<='1'; --0
when "00010110"=> ascii <= "00110001"; hit<='1'; --1
when "00011110"=> ascii <= "00110010"; hit<='1'; --2
when "00100110"=> ascii <= "00110011"; hit<='1'; --3
when "00100101"=> ascii <= "00110100"; hit<='1'; --4
when "00101110"=> ascii <= "00110101"; hit<='1'; --5
when "00110110"=> ascii <= "00110110"; hit<='1'; --6
when "00111101"=> ascii <= "00110111"; hit<='1'; --7
when "00111110"=> ascii <= "00111000"; hit<='1'; --8
when "01000110"=> ascii <= "00111001"; hit<='1'; --9
when "00011100"=> ascii <= "01100001"; hit<='1'; --a
when "00110010"=> ascii <= "01100010"; hit<='1'; --b
when "00100001"=> ascii <= "01100011"; hit<='1'; --c
when "00100011"=> ascii <= "01100100"; hit<='1'; --d
when "00100100"=> ascii <= "01100101"; hit<='1'; --e
when "00101011"=> ascii <= "01100110"; hit<='1'; --f
when "00110100"=> ascii <= "01100111"; hit<='1'; --g
when "00110011"=> ascii <= "01101000"; hit<='1'; --h
when "01000011"=> ascii <= "01101001"; hit<='1'; --i
when "00111011"=> ascii <= "01101010"; hit<='1'; --j
when "01000010"=> ascii <= "01101011"; hit<='1'; --k
when "01001011"=> ascii <= "01101100"; hit<='1'; --l
when "00111010"=> ascii <= "01101101"; hit<='1'; --m
when "00110001"=> ascii <= "01101110"; hit<='1'; --n
when "01000100"=> ascii <= "01101111"; hit<='1'; --o
when "01001101"=> ascii <= "01110000"; hit<='1'; --p
when "00010101"=> ascii <= "01110001"; hit<='1'; --q
when "00101101"=> ascii <= "01110010"; hit<='1'; --r
when "00011011"=> ascii <= "01110011"; hit<='1'; --s
when "00101100"=> ascii <= "01110100"; hit<='1'; --t
when "00111100"=> ascii <= "01110101"; hit<='1'; --u
when "00101010"=> ascii <= "01110110"; hit<='1'; --v
when "00011101"=> ascii <= "01110111"; hit<='1'; --w
when "00100010"=> ascii <= "01111000"; hit<='1'; --x
when "00110101"=> ascii <= "01111001"; hit<='1'; --y
when "00011010"=> ascii <= "01111010"; hit<='1'; --z
when "00111001"=> ascii <= "00100000"; hit<='1'; --spacebar
when "01100110"=> ascii <= "00100000"; hit<='1'; --backspace
when "01110001"=> ascii <= "11100000"; hit<='1'; --del
when others => ascii <= "00100000"; hit<='0'; --' ' for unlisted characters.
end case;
if hit='1' then
if hit_cnt="111111111" then
hit_1<='1';
hit_cnt<="000000000";
else
hit_cnt<=hit_cnt+1;
end if;
else
hit_1<=hit;
end if;
END PROCESS;
end behavioral;

复制代码这个程序里的 if (resetn = '0') then
prv_ps2_clk <= '1';
act_ps2_clk <= '1';
elsif (clock'event and clock = '1') then
act_ps2_clk <= ps2_clk;
prv_ps2_clk <= act_ps2_clk;
end if;

这个部分我不能理解，为什么是时钟的上升沿的时候进行那些操作？？？

shangwfa

5楼-- · 2019-07-16 20:32

精彩回答 2 元偷偷看……

yoonssica

6楼-- · 2019-07-17 01:48

shangwfa 发表于 2013-8-28 12:28
当然有用了，可以用于键盘的解码

这。。。。。。。。。。。

PS2键盘时钟与系统时钟

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