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小弟寫了一個mux 4 to 1的verilog code用xilinx + modelsim SE 6.1f! r. A' e9 U# \; G2 C# y
跑模擬
' a8 p4 T a# a: v- ?( u( n' P可是跑出了的波形都是high Z跟unknown 0 ?/ E8 a$ C& b- l, r5 p
也就是訊號資料檔沒灌進去$ a: G7 g/ {0 K% M4 G7 o# Q
想請問各位大大
- Y9 N \6 n. F1 V" o8 D7 B我該怎麼修改這個錯誤; ~$ |! ?( R1 r7 {/ ]; _7 C$ r( G; m6 W
, r1 z0 v! u$ a# j=======================以下是verilog module code======================
& U7 |! p3 `* P/ o) S6 l8 r/ h0 tmodule mux4_to_1(out, i0, i1, i2, i3, s1, s0);9 J8 K4 d2 { \4 d! V
output out;
+ Q: ]9 \8 w* u2 Y n2 J8 B input i0, i1, i2, i3;
' }8 y3 ^ \: p- q1 i input s1, s0;+ K$ P4 a0 r( y2 z* e6 n
//out declared as register$ Z* i2 }$ B7 Q0 s! s* N
reg out;
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//recompute the signal out if any input signal changes.# m# n( J8 Y( p
//All input signals theat cause a recomputation of out to occur must go into the always@(...)% s+ N1 D9 m% r
always@(s1 or s0 or i0 or i1 or i2 or i3)
0 \- A% D7 q3 {8 c1 @ begin
! n* `1 S1 p Z% b; ^9 n( E r& y" } case({s1, s0})0 I, ~' s% I' C( Y0 b# m" J
2'b00: out=i0;
3 I" ^, P: H+ S5 {4 \* l5 W; W) F 2'b01: out=i1;
/ z0 R; m" }# j 2'b10: out=i2;. d6 y) p2 G' Y A
2'b11: out=i3;
: G& b+ M7 I* O7 C4 J default: out=1'bx;7 q h& c. m- N& }( u% U
endcase( Y3 N& h4 p. n4 }& P4 C
end
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endmodule
5 E2 Q" \9 B1 H! h5 z, p( z& s=======================以下是test bench==========================
+ Z3 v9 M5 s. \5 g6 ]) Imodule stimulus;
2 M3 E+ ?- @& X6 r9 c
. A4 p; `/ l/ a4 u: I0 l* V // Inputs, B7 K+ b2 o* A! \( d9 j1 r7 E
reg I0,I1,I2,I3;5 @# ?* J& P, [# u
reg S1,S0;
- U; t5 y" x' H3 {8 b& b$ ^; P // Outputs
: V8 U0 N: I4 U/ Z" u1 W$ g wire OUT;
! `$ e. f) X( P( \% R( U
' A a d8 f. E4 l$ @9 E6 g // Instantiate the Unit Under Test (UUT)9 A+ Q4 ~6 r: k+ Z1 p+ U
mux4_to_1 uut () e! s% `& B9 E% i9 ?
.out(OUT), 6 X6 e+ U, v8 I- V8 O
.i0(I0),
# C2 E! I) B; Q* D% b$ s7 C) K .i1(I1), & D$ c4 U' N7 {6 H
.i2(I2),
7 @7 C1 a3 k7 _1 z9 \ .i3(I3), . B& j: @% S1 |# D' g2 U; v
.s1(S1),
6 X9 c1 {9 z( b .s0(S0)
( h3 }+ l$ w5 V$ S: g! Q( g );
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initial begin; R& C, s; J2 C5 y
// Initialize Inputs
8 d. X9 v, w# Z+ u9 J I0 = 1;
* p+ h) Z% I9 |( W I1 = 0;
$ t2 d) r9 I& y I2 = 1;
+ ]# Q: o. q! ]. h6 w1 e I3 = 0;
[ b) Z p6 F3 l9 g0 d
' N! c& t! ^- l) B0 J/ g/ y/ j #100 $display("I0=%b, I1=%b, I2=%b, I3=%b\n", I0, I1, I2, I3);
2 n+ V% j+ |. J' o/ t //Choose IN0% W5 K& }0 r: b' i" K, d
S1 = 0;S0 = 0;
7 f5 f$ V c/ Y0 [/ E/ p1 g* b #100 $display("S1=%b, S0=%b, OUT=%b\n", S1, S0, OUT);3 C1 `# W$ m: h l) H- u3 d5 J
//Choose I1
) L5 \- {9 Y" c: j0 q* r3 L( i S1 = 0;S0 = 1;
- W7 T+ s# `9 J- Y2 l- B0 V7 i #100 $display("S1=%b, S0=%b, OUT=%b\n", S1, S0, OUT);6 ?4 U. C/ y" m" \* H5 t$ |% x4 D$ b
//Choose I2
6 A8 M/ G' j: n' C S1 = 1;S0 = 0;
# x! t. K% q( L$ f h #100 $display("S1=%b, S0=%b, OUT=%b\n", S1, S0, OUT);
+ s. [8 [" c4 ]7 I //Choose I3" j+ \6 a! Y6 @. J% X( J4 e8 ?. E6 A3 A
S1 = 1;S0 = 1;4 ?, Q3 X- }. n- v2 T( S& @
#100 $display("S1=%b, S0=%b, OUT=%b\n", S1, S0, OUT);' y( R$ f4 }! b
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: \9 X4 }! m+ n$ ]
end4 G! l/ f; z) l5 U0 C; p1 o
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endmodule |
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