【发布时间】：2014-01-01 19:58:37
【问题描述】：
我的 fpga 是 spartan 3E-100 Cp132。我有四个按钮作为我的输入，我想通过使用它们来增加电路板 7 段上的四个数字。 VHDL代码如下：
entity main is
port(b1,b2,b3,b4 : in STD_LOGIC;
clk : in STD_LOGIC;
sseg : out STD_LOGIC_VECTOR(0 to 6);
anodes : out STD_LOGIC_VECTOR(3 downto 0);
reset : in STD_LOGIC
);
end main;
architecture Behavioral of main is
signal bcd1, bcd2, bcd3, bcd4 : STD_LOGIC_VECTOR (3 downto 0);
signal clk2 : STD_LOGIC;
signal pushbuttons : STD_LOGIC_VECTOR(3 downto 0);
signal db_pushbuttons : STD_LOGIC_VECTOR(3 downto 0);
signal counter : STD_LOGIC_VECTOR(1 downto 0);
signal clk_divider : STD_LOGIC_VECTOR(20 downto 0);
component Debounce is
port( cclk : in STD_LOGIC;
inp : in STD_LOGIC_VECTOR(3 downto 0);
cclr : in STD_LOGIC;
db : out STD_LOGIC_VECTOR(3 downto 0)
);
end component;
begin
pushbuttons <= b4 & b3 & b2 & b1;
Db : Debounce port map
( cclk => clk2,
inp => pushbuttons,
cclr => reset,
db => db_pushbuttons);
process (clk)
begin
if rising_edge(clk) then
if clk_divider <= "1100001101010000" then
clk_divider <= clk_divider + 1;
clk2 <= '0';
else
clk_divider <= (others => '0');
clk2 <= '1';
end if;
end if;
end process;
process (clk2, reset)
begin
if reset = '1' then
-- do something here
bcd1 <= "0000";
bcd2 <= "0000";
bcd3 <= "0000";
bcd4 <= "0000";
elsif rising_edge(clk2) then
counter <= counter + 1;
if db_pushbuttons(0) = '1' then -- db_b1
if bcd1 <= "1000" then
bcd1 <= bcd1 + 1;
else
bcd1 <= "0000";
end if;
elsif db_pushbuttons(1) = '1' then -- db_b2
if bcd2 <= "1000" then
bcd2 <= bcd2 + 1;
else
bcd2 <= "0000";
end if;
elsif db_pushbuttons(2) = '1' then -- db_b3
if bcd3 <= "1000" then
bcd3 <= bcd3 + 1;
else
bcd3 <= "0000";
end if;
elsif db_pushbuttons(3) = '1' then --db_b4
if bcd4 <= "1000" then
bcd4 <= bcd4 + 1;
else
bcd4 <= "0000";
end if;
end if;
end if;
end process;
process (counter, bcd1, bcd2, bcd3, bcd4)
variable display : STD_LOGIC_VECTOR(3 downto 0);
begin
case counter is
when "00" => anodes <= "1110"; display := bcd1;
when "01" => anodes <= "1101"; display := bcd2;
when "10" => anodes <= "1011"; display := bcd3;
when "11" => anodes <= "0111"; display := bcd4;
when others => null;
end case;
case display is
when "0000" => sseg <= "0000001"; --0
when "0001" => sseg <= "1001111"; --1
when "0010" => sseg <= "0010010"; --2
when "0011" => sseg <= "0000110"; --3
when "0100" => sseg <= "1001100"; --4
when "0101" => sseg <= "0100100"; --5
when "0110" => sseg <= "0100000"; --6
when "0111" => sseg <= "0001111"; --7
when "1000" => sseg <= "0000000"; --8
when "1001" => sseg <= "0000100"; --9
when others => sseg <= "0010000"; --e, represents error
end case;
end process;
end Behavioral;
每个按钮都应将相应的 7 段数字（b1 --> 最右边的数字和 b4--> 最左边的数字）加一。问题是当我按下按钮时，它会完成这项工作，但不会将其增加一，而是增加一些任意数字。原因是它在时钟 2 的每个上升沿递增 1，并且由于该时钟的频率，它发生得太快。我怎样才能摆脱这个问题？我尝试了几个按钮的去抖动代码，但它们并没有太大帮助。我完全被困在这里。我的意思是应该有办法做到这一点，但是怎么做呢？顺便说一句，我在上面的代码中一直使用的去抖动代码是
entity Debounce is
port(cclk : in STD_LOGIC;
inp : in STD_LOGIC_VECTOR(3 downto 0);
cclr : in STD_LOGIC;
db : out STD_LOGIC_VECTOR(3 downto 0)
);
end Debounce;
architecture Behavioral of Debounce is
signal delay1, delay2, delay3 : STD_LOGIC_VECTOR(3 downto 0);
begin
process (cclk, cclr)
begin
if cclr = '1' then
delay1 <= "0000";
delay2 <= "0000";
delay3 <= "0000";
elsif rising_edge(cclk) then
delay1 <= inp;
delay2 <= delay1;
delay3 <= delay2;
end if;
end process;
db <= delay1 and delay2 and delay3;
end Behavioral;
所以任何帮助将不胜感激，在此先感谢！
【问题讨论】：
-
clk的频率是多少？
-
我猜应该是 50MHz。它是 FPGA 上的标准时钟。
标签： button push vhdl synclock debouncing