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仿真的时候就是不对。。。
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library ieee;
. M; C; ^4 R- ^; [; a+ ?use ieee.std_logic_1164.all;
3 [! C1 U, Z$ b, @& s- I% Z) [% Muse ieee.std_logic_arith.all;2 P. K- i, H& }$ `, {
use ieee.std_logic_unsigned.all;
$ S! x! W. F: f* r+ a4 Qentity cnt100 is; y6 ?* }) G1 A6 \
port(clk:in std_logic;( ]3 E! [5 f$ ~4 q- ?$ E/ ~
q ut std_logic_vector(7 downto 0);1 {' h1 j& e( W7 r
c ut std_logic);6 ?9 L9 J( o1 D1 ^# f) ]% [7 V2 f( @
end cnt100;7 j2 X' k1 ]0 _/ k$ u3 o
architecture one of cnt100 is
5 T6 A* b7 A$ F4 fsignal qa:std_logic_vector(3 downto 0);
3 x5 Z* D; b; C/ {7 W* `9 o( Esignal qb:std_logic_vector(3 downto 0);
+ _$ G, S* T% |9 ]6 isignal cin:std_logic;0 r8 P8 O' A G
begin
6 V) l# Y4 J7 Z q(3 downto 0)<=qa;
( ]/ \0 h5 D7 K I+ l q(7 downto 4)<=qb;) @0 o! y3 s* Z7 h" @$ P
process(clk)
+ x K1 M; R* D+ b7 u% v* g! K begin
" N' F" P$ n; @ if clk'event and clk='1' then
$ N, b0 `8 @2 ~3 I0 P if qa=9 then qa<="0000";cin<='1';3 F/ g+ q( a; T
else qa<=qa+1;cin<='0';
8 r" {5 v; T1 O end if;
% |- S4 j3 F4 L. q4 y end if;
: p' d" i" l/ B( X- x end process;
% f8 L& a) w2 G2 Z0 v& V process(clk,cin)
- }7 K% z- N5 G begin- c! g% s: L! N9 U/ ^/ Y
if clk'event and clk='1' then6 I. h! o H, O# O) N) Y
if (qb=9 and qa=9) then qb<="0000";c<='1';8 g3 E5 X. y% T
else c<='0';
7 i& r- p }3 V; _$ r+ t end if;
: _. H' p |; D if cin='1' then qb<=qb+1;) z0 v3 n# [4 k( {9 B H
end if;3 }0 ?9 k: l: q3 V0 h
end if;9 ~4 _4 h& Z, v: o9 p" V/ f
end process;
6 [& q. _3 P" Y5 |& D$ K+ L2 kend one; |
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