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小弟寫了一個mux 4 to 1的verilog code用xilinx + modelsim SE 6.1f
9 U- o( s( |# l7 g# O r$ u跑模擬
" U/ y& j; y! O, d' {! j. t可是跑出了的波形都是high Z跟unknown
4 v3 d9 e5 `! i4 S9 m% h) v也就是訊號資料檔沒灌進去
2 `& J4 d/ s' }想請問各位大大. C4 [$ [9 O! U/ F: y0 t I/ Z
我該怎麼修改這個錯誤0 c9 [% g* s, d2 b) ]% T3 e" D
' J: ]! r0 X- v* S=======================以下是verilog module code======================
5 P; ^, ^$ P& b$ t5 A( _module mux4_to_1(out, i0, i1, i2, i3, s1, s0);
1 T" v# l, \3 X, J! n% t. g output out;
8 d% T4 I; V1 V& l+ V2 Q, |6 U input i0, i1, i2, i3;
( }1 {! |6 j; T4 t* m" b% B% j input s1, s0;% r, ~. s: l+ T+ Y6 _, ^: m
//out declared as register
' N& _ i* K% d* h b6 H reg out;
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- w0 v4 T! O+ _1 b, ] //recompute the signal out if any input signal changes.. K: o s/ Q* D: ~
//All input signals theat cause a recomputation of out to occur must go into the always@(...), k6 n, z, A E8 _. o
always@(s1 or s0 or i0 or i1 or i2 or i3)6 X: }- }5 A1 G& q' _$ ]- p9 K
begin; @, p7 p; j; v) E G2 }
case({s1, s0})
Y8 q* i# K- a) H& {- J4 c. F 2'b00: out=i0;
: c' g) ~! L( h9 D& R 2'b01: out=i1;
# X6 q t5 J. S2 w- r: u$ E$ z* e 2'b10: out=i2;5 M+ q3 x7 z/ \! G! D
2'b11: out=i3;
5 g) _ O& |* u- S3 g# e default: out=1'bx;8 G# T9 V" s: v% R% X3 p3 L# z7 w
endcase
2 V& m6 K- s& \" g. g0 P( E% W end# J& x0 ^ E( o
9 {9 V, C9 a% a4 \3 B( @endmodule
( a4 J8 n6 N( {, E! s: D( e=======================以下是test bench==========================
; U6 U8 P# i% Q" q/ Ymodule stimulus;% b2 `* o" i/ ?2 S2 P% I+ n. F3 G, z
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// Inputs* ~& w0 @' u4 k- S! Z# A) S
reg I0,I1,I2,I3;
% A8 H' J3 @' N7 W* S& J+ G reg S1,S0;+ B6 m f; j3 w+ Q
// Outputs! K# W" l' i8 C; K, U7 N
wire OUT;; A" T2 D3 \, e) K0 W9 x7 w+ c) n& U
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// Instantiate the Unit Under Test (UUT)" F) ^# ~9 s3 k, w$ i! ?: ?1 J
mux4_to_1 uut (" V8 F2 O+ v- h1 ^
.out(OUT), 4 o/ `6 o% ?3 N; G3 W
.i0(I0),
: \% ~: R: S. L( K; S6 {3 `" t: N .i1(I1), 2 @6 Y' l! z( S; P
.i2(I2), }8 \9 g4 L' J% S+ e+ E4 G2 ^+ L3 k
.i3(I3),
: d# @) y: T% ~" u .s1(S1),
, q0 T2 F8 d8 Z, I7 d$ _3 }+ _ .s0(S0)
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initial begin
p% \- M! S2 t/ g: b. l% n* i // Initialize Inputs5 S8 c6 d' A3 `3 k) N/ f
I0 = 1;
# [' Y+ V. L) ^! B7 v9 b6 y R6 e I1 = 0;
. ?, E) m) v/ O7 }* p I2 = 1;
/ M" L6 t3 b# _ I3 = 0;& r, O6 ?8 S4 k4 ], ?
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#100 $display("I0=%b, I1=%b, I2=%b, I3=%b\n", I0, I1, I2, I3);7 M& f3 o" u0 m6 [/ u
//Choose IN0% v3 M+ z' u$ u( a, x A3 s; T
S1 = 0;S0 = 0;
9 F2 P: p# @/ _+ a$ h1 B #100 $display("S1=%b, S0=%b, OUT=%b\n", S1, S0, OUT);
# U7 d) X7 h* l9 a, ^ //Choose I1
% g+ A& b6 A' X3 d6 Q K S1 = 0;S0 = 1;1 _- q) E$ k5 O7 l7 s
#100 $display("S1=%b, S0=%b, OUT=%b\n", S1, S0, OUT);
2 [ w' C( m* M4 E8 V //Choose I28 k$ x/ n/ j+ z: b, @5 h
S1 = 1;S0 = 0;7 V! D9 P8 J h, F Y
#100 $display("S1=%b, S0=%b, OUT=%b\n", S1, S0, OUT); o0 G4 }4 v7 Y
//Choose I3
3 i: H) \, d& e9 M* ?* d S1 = 1;S0 = 1;
9 t- i2 [8 H) Q4 _8 L4 l) @' r5 Z ^ #100 $display("S1=%b, S0=%b, OUT=%b\n", S1, S0, OUT);6 c' }& _( J8 e2 `
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8 @# t* p9 h0 r/ f end
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endmodule |
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