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小弟寫了一個mux 4 to 1的verilog code用xilinx + modelsim SE 6.1f% ^* _2 n9 ]( x9 b* I' X
跑模擬5 I3 c: G! A3 j- `
可是跑出了的波形都是high Z跟unknown 3 z0 L8 @, J8 s# h* o) N
也就是訊號資料檔沒灌進去( N8 S; w$ A0 T. k5 A5 O& _ X
想請問各位大大- i: p6 X H: f8 k4 \/ l) Y" ~0 K" a
我該怎麼修改這個錯誤
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=======================以下是verilog module code======================! m* W, `! V- q4 e5 n# t
module mux4_to_1(out, i0, i1, i2, i3, s1, s0);
- H. M- v$ [' o8 N1 [ output out;+ L) S F/ g, a1 \
input i0, i1, i2, i3;
- P0 L( W6 Y; U, h input s1, s0;
- o% z4 D/ |5 Y2 r! E //out declared as register
: c0 d4 } @1 @ reg out;; S$ N# b7 k1 b M7 \* c. u' V
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//recompute the signal out if any input signal changes.8 x1 i( Q2 a1 P5 \% E( m) g
//All input signals theat cause a recomputation of out to occur must go into the always@(...)
/ Q2 l4 A9 f: Z# E0 m% k+ u always@(s1 or s0 or i0 or i1 or i2 or i3). H3 g" q, y0 T9 ?/ a
begin6 H' ^( z; k& M* D/ i: `+ C5 i
case({s1, s0})
0 x( |" S, n* e* Q" f 2'b00: out=i0;" l6 E( v$ L( }: h, h
2'b01: out=i1;
O5 ~; [; }; ?9 v 2'b10: out=i2;
3 e8 c$ t* ~$ @% b, p 2'b11: out=i3;
9 Q7 t: F* T; F* J) G, } default: out=1'bx;1 c' e' z& F, P6 I& L
endcase3 a/ x, f) h8 e/ ^0 C: R
end
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2 G4 u" K5 z3 J+ G& D, h; K2 o' X1 [endmodule
$ z5 W( ^. n! c=======================以下是test bench==========================
% R( d! d& V5 R( Kmodule stimulus;
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$ W5 Y% j% F; u. a3 F- M // Inputs; L4 C8 {8 c1 }% {6 }$ d
reg I0,I1,I2,I3; I/ f% J$ }2 B; E1 [
reg S1,S0;! D. Q5 p, o0 s7 l
// Outputs
* ^# v7 a8 t2 z; k/ ^8 L; ? wire OUT;
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// Instantiate the Unit Under Test (UUT)
0 |! Q3 S5 M+ S; e mux4_to_1 uut (
0 u' k3 v) {8 _9 \ .out(OUT), 9 B/ e8 N5 R3 t) K# F* j5 c
.i0(I0),
6 z/ a9 I0 n6 O" P. @* ? .i1(I1),
1 B' V" ~' [; `# g+ o( B( S x .i2(I2),
: H9 \6 w: U% l% Z .i3(I3), ; g( v* d% U' w7 w! L/ Q
.s1(S1), : k6 {& k1 Y* @ v
.s0(S0); o! u' x( k$ f, {, [" `
);
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3 g/ K* C6 s/ ~1 \" d+ g initial begin
4 {' d3 X, a" } ?# v // Initialize Inputs( M3 ~$ e0 K0 z L
I0 = 1;, m( P5 w7 W) l+ w
I1 = 0;
2 I) Z6 x* e Y& j I2 = 1;( Y0 t1 k! l( _ v; g/ J) \- i1 G) y
I3 = 0;
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/ v5 p' U* i# J% P% A$ O' T, w #100 $display("I0=%b, I1=%b, I2=%b, I3=%b\n", I0, I1, I2, I3);
& @( g2 y9 A2 j' G //Choose IN0
`5 G& [7 x' P% D. R2 m: o/ Q S1 = 0;S0 = 0;$ b9 M& W8 h7 W* a# Z
#100 $display("S1=%b, S0=%b, OUT=%b\n", S1, S0, OUT);- \* y+ n3 ~1 `" H: U
//Choose I1
8 `# O2 E0 s ]% q6 \( m S1 = 0;S0 = 1;
) G. L; E8 S+ J$ {! D #100 $display("S1=%b, S0=%b, OUT=%b\n", S1, S0, OUT);$ V( w# c8 Y2 K; r8 {8 g
//Choose I22 M$ H1 k2 H9 _' k+ e( d
S1 = 1;S0 = 0;5 j7 ^* C1 x) H+ i' K. L
#100 $display("S1=%b, S0=%b, OUT=%b\n", S1, S0, OUT);6 r& t. j' k( U, ]
//Choose I3& T4 f. W% Q& x3 h0 c. l0 n
S1 = 1;S0 = 1;
+ X' U0 {' g, B0 n3 J/ p9 y2 q #100 $display("S1=%b, S0=%b, OUT=%b\n", S1, S0, OUT);
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) E$ r; M3 r* X j5 B2 u8 u5 w* ` J end3 m0 @6 b8 e" i, e1 x3 S/ I" E
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endmodule |
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