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小弟寫了一個mux 4 to 1的verilog code用xilinx + modelsim SE 6.1f1 P+ k# n& J& R0 L7 j
跑模擬
% {2 f5 n+ L, @7 P) J2 l可是跑出了的波形都是high Z跟unknown ) w* Z5 i! F# s9 w
也就是訊號資料檔沒灌進去% @" L* d, K6 ?+ T* ^3 [* t2 w
想請問各位大大- a* \/ W3 \- n9 p# P% r% ?; S
我該怎麼修改這個錯誤
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. n ]" c9 ^0 x7 ]1 C- f=======================以下是verilog module code======================
: t7 E R- }1 `% a9 D) ~module mux4_to_1(out, i0, i1, i2, i3, s1, s0);
4 l6 @5 W8 t+ L. p output out;8 R6 [5 B& P `+ @
input i0, i1, i2, i3;
1 S g* c- D9 J! _- ]/ k2 N5 G _ input s1, s0;, n A! Q4 F6 z4 c4 L1 z
//out declared as register
# b/ D9 p. t+ w6 L reg out;+ h- q/ {4 u: [4 O$ O
# L% h* U6 {3 Y( s* D! r3 c; J //recompute the signal out if any input signal changes.$ @% K$ F9 {! K& B
//All input signals theat cause a recomputation of out to occur must go into the always@(...)
1 h8 ^6 N- U O always@(s1 or s0 or i0 or i1 or i2 or i3)0 s# F5 p7 T; e+ i7 P% H; l* t
begin
# z P/ p9 C- `/ \& H$ M case({s1, s0})9 k: M$ \2 f7 i6 i
2'b00: out=i0;. u: Q2 V- B" s% E
2'b01: out=i1;
$ o2 W- m( u' t8 [ 2'b10: out=i2;
& ]$ G0 L9 Z" Q( t9 i 2'b11: out=i3;
# @* C. o( R) y* Z6 U* F default: out=1'bx;
! g* A# y% ?; I$ v" o7 d% _: g endcase
) @$ w, b9 Q; U9 I end
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endmodule
7 G% P/ ]6 B. `=======================以下是test bench==========================/ y8 i1 t4 c" R% y, H0 o0 T1 a& j5 A1 o
module stimulus;
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// Inputs1 |7 e9 T; `! Z5 v' i- H6 t! G) z& n
reg I0,I1,I2,I3;
* }7 J5 x6 v1 u) d( o) g( V reg S1,S0;
1 Y8 u* M% i- h3 E2 O r a // Outputs# ~0 M# q+ I2 O! i
wire OUT;
' D8 t; d2 Y# u* k: x8 I
8 p" F! w7 X g1 L+ W // Instantiate the Unit Under Test (UUT)7 M8 R+ ^: ], L2 v
mux4_to_1 uut (% I3 ?' |, G# w2 h5 z' |
.out(OUT), 5 @0 w4 W t' C9 L7 E- w
.i0(I0), . k- g2 \( Q# {6 n2 I, @+ C8 Z
.i1(I1),
' M: b- A" N7 `* U) `7 h& J .i2(I2),
: {( M y, A) A+ P5 @( [ .i3(I3), 6 i: } Q' l" O; L* E
.s1(S1), q+ }& G$ [, R. p3 Z m( R: e
.s0(S0)
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* v; L( s- V' c6 S initial begin. b( |, ^+ Y! h5 K" f/ {9 W2 S
// Initialize Inputs$ \1 c W! M( o+ y, U
I0 = 1;
& Q) V! n# O |7 D! Y I1 = 0;3 W' x8 a& a4 `, z+ y
I2 = 1;7 [& O; h4 S' M% a
I3 = 0;
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#100 $display("I0=%b, I1=%b, I2=%b, I3=%b\n", I0, I1, I2, I3);/ K9 j9 E. w# G; X
//Choose IN0" K( ^6 S$ z5 X, v, v- [
S1 = 0;S0 = 0;
" R1 J) H* _" T, A& ~ #100 $display("S1=%b, S0=%b, OUT=%b\n", S1, S0, OUT);3 ]+ _% u* |0 ?4 G6 K; y
//Choose I1- o' X$ _8 z. P4 v; z6 y; C6 ]9 f
S1 = 0;S0 = 1;& B# ]( F) Q' u; n
#100 $display("S1=%b, S0=%b, OUT=%b\n", S1, S0, OUT);% o1 z& Z; e7 z) N* S0 Q( X6 _
//Choose I2. I2 D0 S/ a+ l+ p$ [* V( M
S1 = 1;S0 = 0;
( `7 C) j1 k4 s$ ~! c. { #100 $display("S1=%b, S0=%b, OUT=%b\n", S1, S0, OUT);
( \. c8 ^% W4 P //Choose I3
, J* t' Q4 C. B S1 = 1;S0 = 1;: A% A9 F4 e) `. a4 x
#100 $display("S1=%b, S0=%b, OUT=%b\n", S1, S0, OUT);
) ~1 H2 Y# x; g5 r0 }
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end
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# e& _& A1 C+ N) H% nendmodule |
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