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module key_filter(clk, rst_n, key_n, click_n);! O$ }4 s# z% j# N% s2 q4 ^
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parameter MASK_TIME = 100;
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input clk;
, K0 A! u0 O6 B2 [& o0 y4 E/ q' O input rst_n;5 m/ |' h! v9 J: T, y C
input key_n;) w- y9 r" G, R5 X ^
output reg click_n;- a0 T: g" a* m- i& c6 |
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localparam s0 = 1'b0;
8 J" A' V7 }* Q r! s$ f* @" P, N4 n localparam s1 = 1'b1;4 m; }; y0 h7 F. y1 X" M
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reg temp;2 _ Z/ H9 H, P) V- B% B; p- |
reg [31:0] count;
! Z! j' ?7 l+ L reg state;
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/ M* E7 J. ^( _. w- ]! } always @ (posedge clk, negedge rst_n)- A; @) G, Q/ @( I) W
begin1 v% D$ Z4 Q: Y- D
if (!rst_n)
2 B- h9 O( i( `( T2 t2 Q begin
- B; n8 r- _* c, a count <= 0;
% ~+ u# u/ m( l. E6 R, p click_n <= 1;
! q% X" x) v1 H, r& s9 J7 y+ l temp <= 1;
/ O8 r. |9 r& |' b& r* ^8 | state <= s0;$ x) u( n+ D6 G! y
end3 r2 A6 C+ l% e( k% Y" h
else L2 {8 T7 B$ Y! X" C, E2 d
case (state)
( o r* u1 p( M* H/ ]$ g% F- P9 q s0 : if (key_n == temp)# [2 c8 C/ U4 Z7 j; {
state <= s0;' G u, K. U/ h6 j/ g
else4 ^6 `( y* l2 T% P9 u U7 N5 w
begin" H8 N+ V. B7 }
temp <= key_n;
3 j- G0 Z3 G) E state <= s1;
# \6 [: c0 H! S8 { end
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& d+ ~5 l1 t$ m$ ?) J/ \. O s1 : if (key_n == temp)" \0 Z6 U+ `) h3 ?" \# l9 y
if (count < MASK_TIME)
3 ~+ Z. J0 l! ~1 o2 V: Q/ z3 q. F begin
4 V W& |0 G3 r4 \ I0 }7 C; p, h count <= count + 1; _8 `( w2 l z l/ d. ]
state <= s1;
8 F8 [( y5 p; E8 Y$ {) h% I- O end
4 d5 x7 R2 ]( H else
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click_n <= temp;, a* Y* D/ Q6 @3 R! D. @, Q+ n
count <= 0;
" M, m+ H2 L. ~$ B X- K: K state <= s0;7 x4 ?9 z0 y/ ]* c
end
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begin
0 K3 d/ ]6 w& y$ J* l count <= 0;7 _7 Y, Y u L. m' N* }2 F! K8 v
temp <= key_n;& m! J. z" l$ R
state <= s1;
, s9 {& Z6 t6 h! P end
$ x: O+ g6 \: K9 Z4 I endcase# O" E X: \6 K5 T2 A X: j5 ^. n
end
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endmodule | " k. q8 A# @* B6 y5 ]* l
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