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小弟寫了一個mux 4 to 1的verilog code用xilinx + modelsim SE 6.1f
* ~' K3 z9 q3 L1 U3 m0 j+ c6 L1 V! ~跑模擬" l+ W' b, {* ]- y1 m/ ~5 K
可是跑出了的波形都是high Z跟unknown
' Y% f2 E7 y+ S& f也就是訊號資料檔沒灌進去* D0 r, e( k0 Y L" Q
想請問各位大大, p! Z" z: D0 p4 c6 t2 N
我該怎麼修改這個錯誤+ g1 k0 N) G0 T6 }$ z" a' ?8 Q* Q1 L
# J4 D: [' ]# d( L7 H=======================以下是verilog module code======================9 ]) o7 B2 r1 d7 M# d
module mux4_to_1(out, i0, i1, i2, i3, s1, s0);, R% } I5 d% \( z6 ]
output out;* K3 y+ j. L: B6 f
input i0, i1, i2, i3;
8 c n+ D4 p9 w: B+ f input s1, s0;
3 G! v" D0 H }9 L$ j4 \7 i8 P //out declared as register0 D) s" \" P: Q; k; \: B$ c% T' A
reg out;
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//recompute the signal out if any input signal changes.
) j7 w0 Y8 i5 ^. h2 A+ u" x //All input signals theat cause a recomputation of out to occur must go into the always@(...)
& o; J, Y1 O! \8 G0 u8 g9 ~/ E4 F* { always@(s1 or s0 or i0 or i1 or i2 or i3). Q6 Q& y& W# n) Y( ^+ V' O9 v) q
begin
1 J8 i" A( A2 I& } case({s1, s0})
! }$ `& w, G& T: D O2 s8 {+ A 2'b00: out=i0;
% ]0 f! v% W3 f 2'b01: out=i1;
7 i* |1 I9 Z/ _) e1 } 2'b10: out=i2;) C8 B H$ F# n0 h; K
2'b11: out=i3;
7 U. g, v; A/ V( f/ G& g! j default: out=1'bx;
: C0 C, g; M' H; E/ Y) S# x endcase
* l9 a1 e5 d, _5 X6 Z \ end
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' _! R: }% p. F+ R$ F0 k' lendmodule
) }. |, J6 l7 u9 R9 k6 y=======================以下是test bench==========================7 i+ i* x4 k4 e4 K. M, U
module stimulus;
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1 Q8 {5 k. ?1 U // Inputs/ e6 B' K& P, s6 Z+ Q6 p0 W2 h
reg I0,I1,I2,I3;
! R+ G* I7 `' c reg S1,S0;
: ^& `2 e# h+ j2 n: U4 b // Outputs+ W& h( s, B9 |% T2 q( y
wire OUT;
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// Instantiate the Unit Under Test (UUT)4 Y. n2 R% U! @, ]' {
mux4_to_1 uut (
, @: Y/ {! Z' ~0 \8 a2 ^, j) i1 R .out(OUT),
! E4 {2 }, O1 _. h .i0(I0), 8 F$ l: A) I6 H5 ^8 h* a" x
.i1(I1),
: ~5 V ~+ L8 y: _: }2 c .i2(I2), $ U) X' @; |* v! n+ s
.i3(I3), . ^+ p0 M. v* O' h, K
.s1(S1),
. r9 i0 n# }" m .s0(S0)
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7 W( n" [) A" ^2 H: J( a" ` initial begin
. y; e: u9 O% P6 A" m7 n1 @. A // Initialize Inputs0 r* D+ }( A: A
I0 = 1;
# `3 A9 b4 h% L3 C; T, r( l I1 = 0;
0 B, W8 l' l, x2 y I2 = 1;# a4 r; R; K+ A* e9 G8 k
I3 = 0;; L# _+ B3 b' E! T3 i- T
$ U9 Z* E5 g+ X; E* V2 ?' X #100 $display("I0=%b, I1=%b, I2=%b, I3=%b\n", I0, I1, I2, I3);3 o$ s5 k h( Z9 F( l" O
//Choose IN0. W* U) A3 @4 w( R! L
S1 = 0;S0 = 0;
+ `% I2 X& b$ W #100 $display("S1=%b, S0=%b, OUT=%b\n", S1, S0, OUT);
$ f% w2 ?) a& V6 ~, G1 E //Choose I1
( P% i; B0 y% N S1 = 0;S0 = 1;* e) Y' I" E b* z0 c9 v. B/ Y0 K
#100 $display("S1=%b, S0=%b, OUT=%b\n", S1, S0, OUT); v; V) U% M8 M x, D# w; z
//Choose I2
" T6 {4 z) r' i" W) E! @ S1 = 1;S0 = 0;
; O2 b! e$ d5 P #100 $display("S1=%b, S0=%b, OUT=%b\n", S1, S0, OUT);
) e |3 l# Q! ~# |7 E6 K0 O% P0 M$ r- | //Choose I37 p. Z# [+ _" O
S1 = 1;S0 = 1; C S1 v- m" {* @- ~; t
#100 $display("S1=%b, S0=%b, OUT=%b\n", S1, S0, OUT);) r& N2 x6 U6 V; V3 O; e
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end& R- @: T8 b- Z( D
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endmodule |
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