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Altera推荐的带异步清零,使能的D触发器的写法
2 v/ o; M+ L. U4 @. y: ?0 D E: amodule dff_control(clk, aclr, aload, ena, data, adata, q);
" v# {6 I; [1 m+ ]1 a- Y" iinput clk, aclr, aload, ena, data, adata;
# R: |& D1 H0 I6 C8 a, M4 f: w, `output q;
# ?+ n) q% q! s( Wreg q;! a$ I8 | }6 H, f# M0 v
always @ (posedge clk or posedge aclr or posedge aload): ?: p+ R! {2 X, z# }: O
begin
% L1 c3 Z; M, _: [2 T; t/ xif (aclr)
7 v8 ~1 k' Z/ s( h3 c: }* ?q <= 1'b0;
+ ^9 Q, {/ ^2 a" A" ?* p6 u4 x/ aelse if (aload)
4 n/ W r5 G. S) y/ m, h$ Jq <= adata;2 n4 [9 ]9 X( b: j) C) x4 `
else if (ena)! i& V% b" r! Q; c. K
q <= data;- i4 A- `' D; ~' O
end2 z; L/ }4 C9 I' v) |' v$ B
endmodul 1 V* s8 J# ~5 R; z9 F
3 C% H7 T( B8 @( i. w2 V9 x( ?8 ?( Z
* y' J8 h& A+ Y- f/ o Q6 T
: _! a, {; u/ y* wLIBRARY ieee;
/ E& ~( Z# n% {3 k7 y: WUSE ieee.std_logic_1164.all;
$ h. H8 h. ^$ [# `) p p5 S& [/ }ENTITY dff_control IS
/ Z' u. e, H* @; y) }8 l APORT (1 t6 U! w y/ W' d9 z
clk: IN STD_LOGIC;
V% m# j6 r3 H$ ^4 caclr: IN STD_LOGIC;$ L Z, D1 B- m* u9 `2 s
aload: IN STD_LOGIC;0 r' r. I1 y" N. [! b0 F
adata: IN STD_LOGIC;9 a- R2 b4 L4 X+ {0 D
ena: IN STD_LOGIC;# H H: I1 c s: _, e1 z+ _. R
data: IN STD_LOGIC;2 A8 L) j6 [7 u) H7 W
q: OUT STD_LOGIC
7 x5 t! D6 S, \8 X$ r# ^);
- A8 G9 \7 U5 [/ H# }* Y# wEND dff_control;
9 b' ]+ i$ N9 L& r& ^- T: T% V g# ^8 m& i) z9 T8 X
ARCHITECTURE rtl OF dff_control IS
1 o( G3 T' r& CBEGIN+ A0 \& Q5 ~5 ]8 V* n
PROCESS (clk, aclr, aload, adata)
( U4 S6 y% ]4 N* H8 O4 P6 {0 @% yBEGIN
/ ?8 Z5 z7 s2 Z( `) AIF (aclr = '1') THEN
9 e. M$ |$ Q0 o3 I+ M: F G7 oq <= '0';) c/ ?/ [+ S( d! L" T/ F( Y
ELSIF (aload = '1') THEN
- n( c5 {+ }* p) R0 J& W) A" f tq <= adata;( @* f) q3 e/ h8 E
ELSE- ^8 s5 V% |6 L5 \' P; k/ R0 a7 v4 G1 ~
IF (clk = '1' AND clk'event) THEN
6 v: B* G$ O& ~, b! |' o# ]IF (ena ='1') THEN: Q4 i0 ?0 U, }! Z
q <= data;
. f3 O, `0 c4 W+ d- I7 x7 v; EEND IF;
8 K/ T5 L9 v# l; w$ ^/ `5 J5 qEND IF;
1 T1 F& i( |- V) N6 sEND IF;
4 y3 J$ |: P, B2 s- y1 I) _) @0 REND PROCESS;$ N7 P# s( I/ |, L& s
END rtl; |
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