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小弟寫了一個mux 4 to 1的verilog code用xilinx + modelsim SE 6.1f. }' H' y z6 ~7 F( O1 i
跑模擬
; ]5 }" ^6 Q* i) V$ K6 R可是跑出了的波形都是high Z跟unknown + V- t; ~# Q8 w2 {
也就是訊號資料檔沒灌進去
# J5 A4 A7 H- z想請問各位大大
* r; c3 I7 e: h/ @( ~我該怎麼修改這個錯誤" r+ ^* G" N2 ~
% m4 _, k2 W3 b& z2 Z6 Z5 h! X' L6 R=======================以下是verilog module code======================
# B+ a; N% A& w. Cmodule mux4_to_1(out, i0, i1, i2, i3, s1, s0);
# n4 d: k! A( ^0 K& i output out;: q3 s4 h2 `* ]. R
input i0, i1, i2, i3;! V7 R! H7 s" u T# C8 j" ?
input s1, s0;
. P6 r$ ^5 x' K4 M //out declared as register
7 W* _7 q% Z+ [. ]1 a# J reg out;
' D4 Z* x0 V" F1 j' B- r8 ~
) F1 v1 a, m% A) P( p( { //recompute the signal out if any input signal changes.
5 D' S- E# N! X( f/ l/ T$ [ //All input signals theat cause a recomputation of out to occur must go into the always@(...)
u5 r0 @( e: z5 r& B always@(s1 or s0 or i0 or i1 or i2 or i3)
/ B# s( W3 I8 f9 _6 o1 B begin0 \ M! r5 t* o
case({s1, s0})
' g- p2 T l, l$ b 2'b00: out=i0;
* L u& M5 ^, P3 Y0 U5 z& G0 H 2'b01: out=i1;
% `+ a6 K& D/ ^$ o 2'b10: out=i2;
, @; ~4 J* Y/ b 2'b11: out=i3;# c8 }( f- K0 j& s5 E, w# K2 m! V, \3 r
default: out=1'bx;
3 _: {$ r6 }& a) x% c9 U endcase( e& }% ]. [1 K1 C$ a& x5 f
end$ y/ |0 h+ s9 C
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endmodule. a3 U. A1 g6 g9 `5 d
=======================以下是test bench==========================
/ Q1 S0 G9 F8 s8 z7 ?- |module stimulus;: ?- m( C* m) _0 Q% q- G! }
N0 N( i9 [, w" ~! o9 ~" m6 j // Inputs) R: @) o! g( ] q( P' z
reg I0,I1,I2,I3;0 q% w+ R9 a: _! K6 s; g( c
reg S1,S0;, z5 d" v1 b* |8 L1 ^$ U; x
// Outputs
/ Q* i' V: o* J( @ wire OUT;2 Y0 t) ^' k' K! r7 c8 p2 l
0 p1 T, }% f0 l, h! ^7 s // Instantiate the Unit Under Test (UUT)
6 I9 ?8 `) _) r4 k- r+ W5 X mux4_to_1 uut (
3 y1 o1 y, b, Q0 u .out(OUT), ; |- I- l7 i9 ?8 H. I
.i0(I0),
* o6 c# q& ?: F- O' O .i1(I1),
) P% M0 k3 _8 \$ d( v3 B P* C6 i2 e .i2(I2),
. ]* R/ | Y+ Z .i3(I3), ! K" d/ w, Z, R l+ r
.s1(S1), 6 F* @* j& D: G9 j3 D
.s0(S0)4 s" d" M& [6 ~/ F2 `
);
8 @. i4 \- g5 ~5 t }
- ^8 s' [1 f5 W0 L initial begin2 X( X" V, c. L$ U: y. y7 m
// Initialize Inputs: f( j# V' F+ l% T* S5 s `8 P
I0 = 1;
8 v0 t) X: t# v# ]# u: A0 a I1 = 0;
) G$ n8 ?+ f' e& s8 U, q- v I2 = 1;6 C# `1 i4 ?* r6 J* p' t
I3 = 0;( }- n: U0 D) `, T, i' H
7 h B4 P; T+ w$ Z5 B) s! M: L6 M #100 $display("I0=%b, I1=%b, I2=%b, I3=%b\n", I0, I1, I2, I3);! B) L4 w {- f: c
//Choose IN0) A; z; l7 L; w5 S( X" k- j3 W
S1 = 0;S0 = 0;2 T. I7 G+ m9 @% r, {
#100 $display("S1=%b, S0=%b, OUT=%b\n", S1, S0, OUT);
+ b# O/ C. N% L. X //Choose I1
. u D# \+ i1 l S1 = 0;S0 = 1;8 ]; v. x4 y2 W& P; S: J* V
#100 $display("S1=%b, S0=%b, OUT=%b\n", S1, S0, OUT);
* z d- \5 H% Z7 j+ Q8 F5 J //Choose I27 \. U6 `3 e( r6 b) {. ^
S1 = 1;S0 = 0;" l" D+ \. t- n+ v
#100 $display("S1=%b, S0=%b, OUT=%b\n", S1, S0, OUT);( I/ t0 r4 H2 _8 `, @4 C
//Choose I3# x Q+ M+ B: B1 D1 M
S1 = 1;S0 = 1;
2 {, M# f' s J. C #100 $display("S1=%b, S0=%b, OUT=%b\n", S1, S0, OUT);
- u; f+ I1 K: p3 P7 Z0 N# y
$ a- G. o0 P" |% A" O4 G/ B0 ~+ U
" d8 [; ]/ S& G9 T) P2 A+ Q( g% t end
* w- w4 D- d. |" V/ P5 m5 h
3 o2 R8 R) _ f. w5 Z0 u0 O7 Uendmodule |
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