关于VGA的问题请教大神，非常感谢!

cj223356

请教大神，
% T* c9 C3 ~6 ~- Z: ^
我根据特权同学的FPGA教程，写了一个VGA的程序。程序下进去后，提示
* y9 N9 ~0 ~6 S5 M输入信号超出范围。我的电脑最低分辨率800*600,程序里是640*480.
+ G4 j7 C% `# |" E! Y然后我改了一下，不超出范围了，却提示节点模式。
程序如下：
- d6 r4 e0 |$ o0 h+ _' B- j5 Lmodule VGA(
: t. e$ W" \/ W3 P   clk,rst_n,   //系统控制
3 ]2 n! U8 D9 x. r. V, d, V   hsync,vsync,
7 c, D7 S4 {. }4 v! a4 m" H   vga_r,vga_g,vga_b  //VGA控制
   );
   
) b. X% \" |7 Z* W- Uinput clk;  //50M
input rst_n; //低电平复位
//FPGA与VGA接口信号
; V$ g+ B, m, Joutput hsync;   //行同步信号
* x- F6 {$ o  C" J* a  d/ X! goutput vsync;   //场同步信号
4 F1 b6 l( S6 s: h1 zoutput[2:0] vga_r;
) f3 m, N" w2 Goutput[2:0] vga_g;
output[1:0] vga_b;
& \- q' H# _. [; [2 V  K# [
//坐标计数
; _( H! V. O- I  m0 Lreg[10:0] x_cnt;  //行坐标
reg[9:0] y_cnt;  //列坐标
. _' x! o+ W! P+ \  L. a9 j1 r8 p
7 [- A  @, R+ xalways @(posedge clk or negedge rst_n)
if(!rst_n) x_cnt <= 10'd0;
else if(x_cnt == 10'd1039) x_cnt <= 10'd0;
- @2 p/ F, w: s  n& Lelse x_cnt <= x_cnt+1'b1;
always @(posedge clk or negedge rst_n)
, L/ |; R; S" qif(!rst_n) y_cnt <= 10'd0;
5 V$ @# r8 n! q& j) n( qelse if(y_cnt == 10'd665) y_cnt <= 10'd0;
else if(x_cnt == 10'd1039) y_cnt <= y_cnt+1'b1;
2 n7 ^" X- Y) [7 L9 e$ X//VGA场同步，行同步信号
9 H: z$ d% V! ^7 D& {' D) T1 Zreg hsync_r,vsync_r;   //同步信号
  n4 V  h. E4 _/ falways @(posedge clk or negedge rst_n)
if(!rst_n) hsync_r <= 1'b1;
) U! q1 o1 C# h4 U( ^: G+ S4 }/ `# lelse if(x_cnt == 10'd0) hsync_r <= 1'b0; //产生hsync信号
2 N/ U. u0 o3 J6 L, z8 ~else if(x_cnt == 10'd120) hsync_r <= 1'b1;

always @(posedge clk or negedge rst_n)
if(!rst_n) vsync_r <= 1'b1;
- f* p- x8 T( d7 L- Velse if(y_cnt == 10'd0) vsync_r <= 1'b0; //产生vsync信号
$ N3 d, U9 |* D. V( F# Kelse if(y_cnt == 10'd6) vsync_r <= 1'b1;

' r3 X- k5 Y2 w& F& w9 t0 N; V- }assign hsync =hsync_r;
0 D6 ~; R# }+ c% w$ K* [, S# nassign vsync = vsync_r;
  //有效显示标志位产生
reg valid_yr;  //行显示有效信号
always @(posedge clk or negedge rst_n)
4 b; g5 [+ Q1 d/ Hif(!rst_n) valid_yr <= 1'b0;
1 V$ p2 x/ }7 `2 M! O2 Oelse if(y_cnt == 10'd32) valid_yr <= 1'b1;
else if(y_cnt == 10'd632) valid_yr <= 1'b0;
3 y' m1 t0 J( y& u% k& Z: ewire valid_y=valid_yr;
$ I! T, y1 M- A8 I( E1 creg valid_r;
always @(posedge clk or negedge rst_n)
) g+ A! Q' Z! j' l8 Iif(!rst_n) valid_r <= 1'b0;
0 ], p) |8 V" R+ y2 t  y; yelse if((x_cnt == 10'd187) && valid_y) valid_r <= 1'b1;
else if((x_cnt == 10'd987) && valid_y) valid_r <= 1'b0;

( v" \/ ?) S+ rwire valid=valid_r;
wire[9:0] x_dis;  //横坐标显示有效区域0-639
wire[9:0] y_dis;  //纵坐标显示有效区域0-479
assign x_dis = x_cnt - 10'd187;
+ S/ ?% \; m/ v3 z# Iassign y_dis = y_cnt - 10'd33;
6 }( D7 V& Y4 J. F& n//VGA色彩信号产生
3 `1 ]- o  P7 Y/*
8 m# B, L1 C! }. FRGB = 000 黑色     RGB = 100  红色
  = 001 蓝色         = 101  紫色
  = 010 绿色         = 110  黄色
  = 011 青色         = 111  白色
4 W8 c: m; d; R: L, w+ Q  */
/*
一共640*480个像素点，需要显示256种颜色;
% Z6 r; u6 M( B/ e- @0 y: p那么每个颜色显示区域为40*30，就正好。
! k1 P; n5 p9 D, c*/
reg[7:0] vga_rgb;   //VGA色彩显示寄存器
always @(posedge clk)
* R/ r3 X6 o, u5 U2 Z4 q7 W$ v0 c2 fif(!valid) vga_rgb <= 8'd0;
else begin
. q, S, C, m0 W& g7 t3 m4 z2 b  case(x_dis)
   10'd0: begin  //当x坐标画到0时，让显示色彩数据根据当前的y坐标值重新
    if(y_dis >= 10'd0 && y_dis < 10'd30) vga_rgb <= 8'd0;
% [" j3 {( v" M1 \8 r" O& h    else if(y_dis >= 10'd30 && y_dis < 10'd60) vga_rgb <= 8'd16;
    else if(y_dis >= 10'd60 && y_dis < 10'd90) vga_rgb <= 8'd32;
    else if(y_dis >= 10'd90 && y_dis < 10'd120) vga_rgb <= 8'd48;
    else if(y_dis >= 10'd120 && y_dis < 10'd150) vga_rgb <= 8'd64;
: ]" ]2 ?1 Z  k! C    else if(y_dis >= 10'd150 && y_dis < 10'd180) vga_rgb <= 8'd80;
! C$ O  g5 b- \5 K    else if(y_dis >= 10'd180 && y_dis < 10'd210) vga_rgb <= 8'd96;
    else if(y_dis >= 10'd210 && y_dis < 10'd240) vga_rgb <= 8'd112;
    else if(y_dis >= 10'd240 && y_dis < 10'd270) vga_rgb <= 8'd128;
: s  I0 S; X7 k8 S" o- M    else if(y_dis >= 10'd270 && y_dis < 10'd300) vga_rgb <= 8'd144;
2 G  F( l9 e8 U" C/ x    else if(y_dis >= 10'd300 && y_dis < 10'd330) vga_rgb <= 8'd160;
    else if(y_dis >= 10'd330 && y_dis < 10'd360) vga_rgb <= 8'd176;
    else if(y_dis >= 10'd360 && y_dis < 10'd390) vga_rgb <= 8'd192;
9 ]6 t( d  D9 h, H: r& ^    else if(y_dis >= 10'd390 && y_dis < 10'd420) vga_rgb <= 8'd208;
; J0 k8 I( ]' p    else if(y_dis >= 10'd420 && y_dis < 10'd450) vga_rgb <= 8'd224;
( h! z- A& F7 n1 D) i# g    else if(y_dis >= 10'd450 && y_dis < 10'd480) vga_rgb <= 8'd240;
    else if(y_dis >= 10'd480 && y_dis < 10'd510) vga_rgb <= 8'd256;
: ]* f/ I3 O6 t2 h6 p/ d! o0 \    else if(y_dis >= 10'd510 && y_dis < 10'd540) vga_rgb <= 8'd272;
    else if(y_dis >= 10'd540 && y_dis < 10'd570) vga_rgb <= 8'd288;
. l3 P5 l) @9 t, H! D: M7 b2 N    else vga_rgb <= 8'd304;
' ]+ S: Z  c) P" C: m8 l) v   end
" F/ J$ Q3 S. r4 X! c* s  10'd40,10'd80,10'd120,10'd160,10'd200,10'd240,10'd280,10'd320,10'd360,10'd400,10'd440,10'd480,
  10'd520,10'd560,10'd600,10'd640,10'd680,10'd720,10'd760,10'd800: vga_rgb <= vga_rgb + 1'b1;
  default:;
  endcase
/ D, ]# o' Q" b3 _* F$ Iend
assign vga_r = vga_rgb[7:5];
assign vga_g = vga_rgb[4:2];
' q3 g# c. a' v7 X6 l6 E5 Dassign vga_b = vga_rgb[1:0];
endmodule
请大神帮忙看看，非常感谢！
# A+ d& h2 W! u% g

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