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小弟寫了一個mux 4 to 1的verilog code用xilinx + modelsim SE 6.1f
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可是跑出了的波形都是high Z跟unknown ( {6 s* G' L1 `
也就是訊號資料檔沒灌進去
8 s6 [' O- \! _) N9 p2 n* _ L想請問各位大大
$ u7 w3 y2 w0 L- H* z我該怎麼修改這個錯誤
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/ a; L" N5 Q: ^* X+ Z6 s=======================以下是verilog module code======================1 S# e3 @* g. Z: m& J
module mux4_to_1(out, i0, i1, i2, i3, s1, s0);
& s2 A3 n; {% e$ ]+ j g# o output out;# Z# T$ N+ l4 h, _1 ]: i7 N
input i0, i1, i2, i3;. G$ F( F. c, r! f) C; H [
input s1, s0;
3 ~" x1 Y5 E! E1 S* @ //out declared as register8 ^- V c2 s/ K; n
reg out;
+ [( I" I `$ {) _' B
* P+ w! {& J6 } //recompute the signal out if any input signal changes.$ g$ `& X, d5 @3 C M& E( c" h5 c
//All input signals theat cause a recomputation of out to occur must go into the always@(...)' F' [. Z- x% N! o! K' P
always@(s1 or s0 or i0 or i1 or i2 or i3)
y2 `- d+ t6 ? begin0 _' Q' N j# f9 c0 p5 {! }
case({s1, s0})7 S% X& s& H( [5 T* m+ H
2'b00: out=i0;$ |% }$ F0 g0 G0 d- O# t- k5 ]6 s
2'b01: out=i1;! o0 c- `$ \+ k6 Q3 m9 b6 |* A& U& V4 b @! B
2'b10: out=i2;, e8 Y1 C( y, M7 x/ r, x
2'b11: out=i3;
) _7 e: T) n- |* f default: out=1'bx;5 y# G% B9 P. x$ g5 g$ ^% g
endcase9 W) F( i' J/ |* t
end$ m( F- c8 }& c
" z! M% @, _' o1 D! kendmodule
- |# d4 S4 o! A/ |: y7 u=======================以下是test bench==========================7 r/ s! {) {) j1 s- u. B% U& V7 z
module stimulus;
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// Inputs% ^. Q- D2 p w6 Y9 N' Z
reg I0,I1,I2,I3;# K0 L- K$ [+ I( e9 w$ E: J' f
reg S1,S0;
% u% \" ?& x, _9 |/ A* u // Outputs
8 t+ \1 c- M3 J$ \4 W8 r wire OUT;; Y# E/ @- e. U' t. j
) S2 D* ~" b, J3 F // Instantiate the Unit Under Test (UUT)6 M* l+ x7 Y5 j$ k t
mux4_to_1 uut (5 }1 Y0 h; u. W/ A
.out(OUT), % b, E9 Y+ s; F8 k) S
.i0(I0), $ x o" d" f# M! N
.i1(I1), . z( S6 L# h V. E q
.i2(I2),
' z9 ]" s W. E* Y% e" l1 S .i3(I3), ; Q' A3 w- S! i: v
.s1(S1), 6 P7 y& y1 m, Y6 ~5 u6 i
.s0(S0)5 k' `& c$ k% x1 m+ M7 s2 P: {: q% M
);
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: w0 U7 L. ^. H8 I G+ k9 u4 C" ~; L initial begin
9 s5 E1 t- H7 x6 B: X$ F! ]0 B5 i // Initialize Inputs, E- X- m3 V. {( B2 A
I0 = 1;
. c. |7 N( C" _5 M I1 = 0;
, W5 }$ ?! \4 f) E: m I2 = 1;
" p! G! g# W& \. B3 z I3 = 0;% c& ?4 H2 s- H5 Z4 w, f
" a! j3 e5 v! H5 ~& W' O #100 $display("I0=%b, I1=%b, I2=%b, I3=%b\n", I0, I1, I2, I3);0 i6 z' g4 F" P. a
//Choose IN03 x! p6 i9 D8 e/ ^' T
S1 = 0;S0 = 0;8 ^0 |: x0 F1 k! p
#100 $display("S1=%b, S0=%b, OUT=%b\n", S1, S0, OUT);* V, F0 j. o M- p9 j3 W
//Choose I1, e* N1 K( T8 K# [& n
S1 = 0;S0 = 1;( M0 F; n- R2 w7 q8 q% o0 U
#100 $display("S1=%b, S0=%b, OUT=%b\n", S1, S0, OUT);
4 _' j; g$ x! i; x4 l3 ^: f" G //Choose I2
: Z; f% f$ F+ ]& u4 a3 g S1 = 1;S0 = 0;
4 e5 t- L; q% ?, |( ~ #100 $display("S1=%b, S0=%b, OUT=%b\n", S1, S0, OUT);+ Z5 _2 |6 z0 a
//Choose I3+ F8 ^4 v# W% m) a* A
S1 = 1;S0 = 1;6 R7 Q P' V4 \( F3 R) }
#100 $display("S1=%b, S0=%b, OUT=%b\n", S1, S0, OUT);
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W' M1 O; h& W8 b2 V
& O- O2 P* D. J8 D, ^5 s: D3 E3 X end
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% F) f8 K7 J+ O' |0 Tendmodule |
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