FPGA中VGA的时序控制 （程序+全注释）

module VGA_test(
OSC_50,     //原CLK2_50时钟信号
VGA_CLK,    //VGA自时钟
VGA_HS,     //行同步信号
VGA_VS,     //场同步信号
VGA_BLANK,  //复合空白信号控制信号  当BLANK为低电平时模拟视频输出消隐电平，此时从R9~R0,G9~G0,B9~B0输入的所有数据被忽略
VGA_SYNC,   //符合同步控制信号      行时序和场时序都要产生同步脉冲
VGA_R,      //VGA绿色
VGA_B,      //VGA蓝色
VGA_G);     //VGA绿色
 input OSC_50;     //外部时钟信号CLK2_50
 output VGA_CLK,VGA_HS,VGA_VS,VGA_BLANK,VGA_SYNC;
 output [7:0] VGA_R,VGA_B,VGA_G;
 parameter H_FRONT = 16;     //行同步前沿信号周期长
 parameter H_SYNC = 96;      //行同步信号周期长
 parameter H_BACK = 48;      //行同步后沿信号周期长
 parameter H_ACT = 640;      //行显示周期长
 parameter H_BLANK = H_FRONT+H_SYNC+H_BACK;        //行空白信号总周期长
 parameter H_TOTAL = H_FRONT+H_SYNC+H_BACK+H_ACT;  //行总周期长耗时
 parameter V_FRONT = 11;     //场同步前沿信号周期长
 parameter V_SYNC = 2;       //场同步信号周期长
 parameter V_BACK = 31;      //场同步后沿信号周期长
 parameter V_ACT = 480;      //场显示周期长
 parameter V_BLANK = V_FRONT+V_SYNC+V_BACK;        //场空白信号总周期长
 parameter V_TOTAL = V_FRONT+V_SYNC+V_BACK+V_ACT;  //场总周期长耗时
 reg [10:0] H_Cont;        //行周期计数器
 reg [10:0] V_Cont;        //场周期计数器
 wire [7:0] VGA_R;         //VGA红色控制线
 wire [7:0] VGA_G;         //VGA绿色控制线
 wire [7:0] VGA_B;         //VGA蓝色控制线
 reg VGA_HS;
 reg VGA_VS;
 reg [10:0] X;             //当前行第几个像素点
 reg [10:0] Y;             //当前场第几行
 reg CLK_25;
 always@(posedge OSC_50)
begin 
 CLK_25=~CLK_25;         //时钟
end 
assign VGA_SYNC = 1'b0;   //同步信号低电平
assign VGA_BLANK = ~((H_Cont<H_BLANK)||(V_Cont<V_BLANK));  //当行计数器小于行空白总长或场计数器小于场空白总长时，空白信号低电平
assign VGA_CLK = ~CLK_to_DAC;  //VGA时钟等于CLK_25取反
assign CLK_to_DAC = CLK_25;
 always@(posedge CLK_to_DAC)
begin
if(H_Cont<H_TOTAL)           //如果行计数器小于行总时长
H_Cont<=H_Cont+1'b1;      //行计数器+1
else H_Cont<=0;              //否则行计数器清零
if(H_Cont==H_FRONT-1)        //如果行计数器等于行前沿空白时间-1
VGA_HS<=1'b0;             //行同步信号置0
if(H_Cont==H_FRONT+H_SYNC-1) //如果行计数器等于行前沿+行同步-1
VGA_HS<=1'b1;             //行同步信号置1
if(H_Cont>=H_BLANK)          //如果行计数器大于等于行空白总时长
X<=H_Cont-H_BLANK;        //X等于行计数器-行空白总时长   （X为当前行第几个像素点）
else X<=0;                   //否则X为0
end
 always@(posedge VGA_HS)
begin
if(V_Cont<V_TOTAL)           //如果场计数器小于行总时长
V_Cont<=V_Cont+1'b1;      //场计数器+1
else V_Cont<=0;              //否则场计数器清零
if(V_Cont==V_FRONT-1)       //如果场计数器等于场前沿空白时间-1
VGA_VS<=1'b0;             //场同步信号置0
if(V_Cont==V_FRONT+V_SYNC-1) //如果场计数器等于行前沿+场同步-1
VGA_VS<=1'b1;             //场同步信号置1
if(V_Cont>=V_BLANK)          //如果场计数器大于等于场空白总时长
Y<=V_Cont-V_BLANK;        //Y等于场计数器-场空白总时长    （Y为当前场第几行）  
else Y<=0;                   //否则Y为0
end
reg valid_yr;
 always@(posedge CLK_to_DAC)
if(V_Cont == 10'd32)         //场计数器=32时
valid_yr<=1'b1;           //行输入激活
else if(V_Cont==10'd512)     //场计数器=512时
valid_yr<=1'b0;           //行输入冻结
wire valid_y=valid_yr;       //连线   
reg valid_r;            
 always@(posedge CLK_to_DAC)   
if((H_Cont == 10'd32)&&valid_y)     //行计数器=32时
valid_r<=1'b1;                   //像素输入激活
else if((H_Cont==10'd512)&&valid_y) //行计数器=512时 
valid_r<=1'b0;                   //像素输入冻结
wire valid = valid_r;               //连线
wire[10:0] x_dis;     //像素显示控制信号
wire[10:0] y_dis;     //行显示控制信号
assign x_dis=X;       //连线X
assign y_dis=Y;       //连线Y
parameter
char_line00=272'hFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF,
char_line01=272'h00000000000000000000000000000000000000000000000000000000000000000000,
char_line02=272'h00400C0000000000000000000000000000C008000000000000000000000000000000,
char_line03=272'h00700E0000000180000000000000000000E00C0000000000000000800180000000C0,
char_line04=272'h00600C00000003C0000000000000000000C01C0000000000000000FFFF80000001E0,
char_line05=272'h00600C3003FFFC000000000000000080008018000000000000800080018003FFFE00,
char_line06=272'h1FFFFFF8000180007FFE7FF003C80380008018007C1F03C803800080018000000000,
char_line07=272'h00600C0000018000180E18180E3803800104301018040E3803800080018000000000,
char_line08=272'h00600C00000180001802180C080803800FFE30381804080803800080018000000000,
char_line09=272'h00600C000001800018031806180802800C0C7FF818041808028000FFFF8000000000,
char_line0a=272'h007FFC000001800018011806300406C00C0C60300C08300406C00080018000000000,
char_line0b=272'h00600C000001800018001806300404C00C0CC0300C08300404C00080018000000018,
char_line0c=272'h00600C000001801018081806200004C00C0C80300C08200004C0008001800000003C,
char_line0d=272'h007FFC000001803818081806600004C00C0D00300C08600004C0008001803FFFFFFE,
char_line0e=272'h00600C003FFFFFFC1818180C60000C600C0D4030061060000C6000FFFF8000018000,
char_line0f=272'h00600C10000180001FF81818600008600C0E20300610600008600080010000018000,
char_line10=272'h00600C380001800018181FF0600008600C0C10300610600008600008200000418000,
char_line11=272'h3FFFFFFC0001800018081800600008600FFC1830073060000860000C382000718800,
char_line12=272'h003208000001800018081800603F1FF00C0C18300320603F1FF0080C307000E18600,
char_line13=272'h00618C000001800018001800600C10300C0C0C300320600C10300C0C307000C18300,
char_line14=272'h00C106000001800018001800600C10300C0C08300320600C1030060C30C001818180,
char_line15=272'h018101C00001800018001800300C10300C0C003001C0300C1030030C30C0038180C0,
char_line16=272'h030104FC0001800018001800300C30300C0C003001C0300C3030038C318003018060,
char_line17=272'h0C010E380001800018001800180C20180C0C003001C0180C2018018C330006018070,
char_line18=272'h187FF0000001800018001800180C20180C0C003001C0180C2018018C36000C018038,
char_line19=272'h6001000000018000180018000C1060180C0C003000800C106018008C380018018038,
char_line1a=272'h00010000000180007E007E0003E0F83E0C0C0030008003E0F83E000C301010018010,
char_line1b=272'h00010000003F800000000000000000000FFC0C60000000000000000C303820738000,
char_line1c=272'h00010060000F800000000000000000000C0C03E00000000000001FFFFFFC001F8000,
char_line1d=272'h1FFFFFF00007000000000000000000000C0801C00000000000000000000000070000,
char_line1e=272'h00000000000000000000000000000000000000800000000000000000000000020000,
char_line1f=272'h00000000000000000000000000000000000000000000000000000000000000000000;


reg[8:0] char_bit;
always@(posedge CLK_to_DAC)
if(X==10'd144)char_bit<=9'd272;   //当显示到144像素时准备开始输出图像数据
else if(X>10'd144&&X<10'd416)     //左边距屏幕144像素到416像素时    416=144+272（图像宽度）
char_bit<=char_bit-1'b1;       //倒着输出图像信息 
reg[29:0] vga_rgb;                //定义颜色缓存
always@(posedge CLK_to_DAC) 
if(X>10'd144&&X<10'd416)    //X控制图像的横向显示边界：左边距屏幕左边144像素  右边界距屏幕左边界416像素
begin case(Y)            //Y控制图像的纵向显示边界：从距离屏幕顶部160像素开始显示第一行数据
10'd160:
if(char_line00[char_bit])vga_rgb<=30'b1111111111_0000000000_0000000000;  //如果该行有数据 则颜色为红色
else vga_rgb<=30'b0000000000_0000000000_0000000000;                      //否则为黑色
10'd162:
if(char_line01[char_bit])vga_rgb<=30'b1111111111_0000000000_0000000000;
else vga_rgb<=30'b0000000000_0000000000_0000000000;
10'd163:
if(char_line02[char_bit])vga_rgb<=30'b1111111111_0000000000_0000000000;
else vga_rgb<=30'b0000000000_0000000000_0000000000;
10'd164:
if(char_line03[char_bit])vga_rgb<=30'b1111111111_0000000000_0000000000;
else vga_rgb<=30'b0000000000_0000000000_0000000000;
10'd165:
if(char_line04[char_bit])vga_rgb<=30'b1111111111_0000000000_0000000000;
else vga_rgb<=30'b0000000000_0000000000_0000000000; 
10'd166:
if(char_line05[char_bit])vga_rgb<=30'b1111111111_0000000000_0000000000;
else vga_rgb<=30'b0000000000_0000000000_0000000000;
10'd167:
if(char_line06[char_bit])vga_rgb<=30'b1111111111_0000000000_0000000000;
else vga_rgb<=30'b0000000000_0000000000_0000000000; 
10'd168:
if(char_line07[char_bit])vga_rgb<=30'b1111111111_0000000000_0000000000;
else vga_rgb<=30'b0000000000_0000000000_0000000000;
10'd169:
if(char_line08[char_bit])vga_rgb<=30'b1111111111_0000000000_0000000000;
else vga_rgb<=30'b0000000000_0000000000_0000000000; 
10'd170:
if(char_line09[char_bit])vga_rgb<=30'b1111111111_0000000000_0000000000;
else vga_rgb<=30'b0000000000_0000000000_0000000000;
10'd171:
if(char_line0a[char_bit])vga_rgb<=30'b1111111111_0000000000_0000000000;
else vga_rgb<=30'b0000000000_0000000000_0000000000;
10'd172:
if(char_line0b[char_bit])vga_rgb<=30'b1111111111_0000000000_0000000000;
else vga_rgb<=30'b0000000000_0000000000_0000000000;
10'd173:
if(char_line0c[char_bit])vga_rgb<=30'b1111111111_0000000000_0000000000;
else vga_rgb<=30'b0000000000_0000000000_0000000000;
10'd174:
if(char_line0d[char_bit])vga_rgb<=30'b1111111111_0000000000_0000000000;
else vga_rgb<=30'b0000000000_0000000000_0000000000;
10'd175:
if(char_line0e[char_bit])vga_rgb<=30'b1111111111_0000000000_0000000000;
else vga_rgb<=30'b0000000000_0000000000_0000000000;
10'd176:
if(char_line0f[char_bit])vga_rgb<=30'b1111111111_0000000000_0000000000;
else vga_rgb<=30'b0000000000_0000000000_0000000000;
10'd177:
if(char_line10[char_bit])vga_rgb<=30'b1111111111_0000000000_0000000000;
else vga_rgb<=30'b0000000000_0000000000_0000000000;
10'd178:
if(char_line11[char_bit])vga_rgb<=30'b1111111111_0000000000_0000000000;
else vga_rgb<=30'b0000000000_0000000000_0000000000;
10'd179:
if(char_line12[char_bit])vga_rgb<=30'b1111111111_0000000000_0000000000;
else vga_rgb<=30'b0000000000_0000000000_0000000000;
10'd180:
if(char_line13[char_bit])vga_rgb<=30'b1111111111_0000000000_0000000000;
else vga_rgb<=30'b0000000000_0000000000_0000000000;
10'd181:
if(char_line14[char_bit])vga_rgb<=30'b1111111111_0000000000_0000000000;
else vga_rgb<=30'b0000000000_0000000000_0000000000;
10'd182:
if(char_line15[char_bit])vga_rgb<=30'b1111111111_0000000000_0000000000;
else vga_rgb<=30'b0000000000_0000000000_0000000000;
10'd183:
if(char_line16[char_bit])vga_rgb<=30'b1111111111_0000000000_0000000000;
else vga_rgb<=30'b0000000000_0000000000_0000000000;
10'd184:
if(char_line17[char_bit])vga_rgb<=30'b1111111111_0000000000_0000000000;
else vga_rgb<=30'b0000000000_0000000000_0000000000;
10'd185:
if(char_line18[char_bit])vga_rgb<=30'b1111111111_0000000000_0000000000;
else vga_rgb<=30'b0000000000_0000000000_0000000000;
10'd186:
if(char_line19[char_bit])vga_rgb<=30'b1111111111_0000000000_0000000000;
else vga_rgb<=30'b0000000000_0000000000_0000000000;
10'd187:
if(char_line1a[char_bit])vga_rgb<=30'b1111111111_0000000000_0000000000;
else vga_rgb<=30'b0000000000_0000000000_0000000000;
10'd188:
if(char_line1b[char_bit])vga_rgb<=30'b1111111111_0000000000_0000000000;
else vga_rgb<=30'b0000000000_0000000000_0000000000;
10'd189:
if(char_line1c[char_bit])vga_rgb<=30'b1111111111_0000000000_0000000000;
else vga_rgb<=30'b0000000000_0000000000_0000000000;
10'd190:
if(char_line1d[char_bit])vga_rgb<=30'b1111111111_0000000000_0000000000;
else vga_rgb<=30'b0000000000_0000000000_0000000000;
10'd191:
if(char_line1e[char_bit])vga_rgb<=30'b1111111111_0000000000_0000000000;
else vga_rgb<=30'b0000000000_0000000000_0000000000;
10'd192:
if(char_line1f[char_bit])vga_rgb<=30'b1111111111_0000000000_0000000000;
else vga_rgb<=30'b0000000000_0000000000_0000000000;
default:vga_rgb<=30'h0000000000;   //默认颜色黑色
endcase 
end
else vga_rgb<=30'h000000000;             //否则黑色
assign VGA_R=vga_rgb[23:16];
assign VGA_G=vga_rgb[15:8];
assign VGA_B=vga_rgb[7:0];
endmodule