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VGA display of de2-115 FPGA development board

2022-06-25 13:44:00 【dedsec0x】

Catalog

One 、VGA brief introduction

VGA（Video Graphics Array） Video graphics array yes IBM On 1987 A use proposed in analog signal Computer display standard .VGA The interface means that the computer adopts VGA Special interface for standard output data .VGA The interface has 15 The needle , Divide into 3 row , Each row 5 Holes , The most widely used interface type on graphics card , Most graphics cards have this interface . It transmits red 、 green 、 blue analog signal as well as Synchronous signal ( Horizontal and vertical signals ).

Color difference of common interfaces VGA Interface (D-Sub Interface )

Speaking of VGA Interface , I believe many friends will not be strange , Because this interface is the most important interface on the computer monitor , From the big CRT The era of display has begun ,VGA Interfaces are used , And it has been used up to now , in addition VGA Interfaces are also known as D-Sub Interface . [2]

Many people think that only HDMI Interface To transmit high-definition signals , But this is a misunderstanding that is easy for everyone to enter , Because by VGA The connection of can also display 1080P Image , Even higher resolution can be achieved , So there's no problem using it to connect display devices to watch HD video , And although it is an analog interface , But because of VGA Decompose the video signal into R、G、B Tricolor sum HV Line field signal transmission , Therefore, the loss in transmission is quite small .

VGA Causes of interface generation ： The information processed by the graphics card will eventually be output to the display , The output interface of the graphics card is the bridge between the computer and the display , It is responsible for outputting the corresponding image signal to the display .CRT Monitor For design and manufacturing reasons , Can only accept analog signal Input , This requires the graphics card to output analog signals .VGA The interface is the interface that outputs analog signals on the graphics card ,VGA（Video Graphics Array） Interface , Also called D-Sub Interface . Although the LCD can receive digital signals directly , But many low-end products are designed to match VGA Interface with the graphics card , So we use VGA Interface .

Two 、VGA Implementation code

The code is as follows ：

module VGA_test(
OSC_50,     // primary CLK2_50 Clock signal 
VGA_CLK,    //VGA Self clock 
VGA_HS,     // Line sync 
VGA_VS,     // Field synchronization signal 
VGA_BLANK,  // Composite blank signal control signal    When BLANK It is the blanking level of analog video output at low level , At that moment, from R9~R0,G9~G0,B9~B0 All data entered is ignored 
VGA_SYNC,   // In accordance with the synchronization control signal        Both line timing and field timing should generate synchronization pulses 
VGA_R,      //VGA green 
VGA_B,      //VGA Blue 
VGA_G);     //VGA green 
 input OSC_50;     // External clock signal 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;     // The leading edge signal period of line synchronization is long 
 parameter H_SYNC = 96;      // The period of line synchronization signal is long 
 parameter H_BACK = 48;      // The signal period of the trailing edge of line synchronization is long 
 parameter H_ACT = 640;      // The line display cycle is long 
 parameter H_BLANK = H_FRONT+H_SYNC+H_BACK;        // The total period of line blank signal is long 
 parameter H_TOTAL = H_FRONT+H_SYNC+H_BACK+H_ACT;  // The total line cycle is long and time-consuming 
 parameter V_FRONT = 11;     // The signal period at the front of field synchronization is long 
 parameter V_SYNC = 2;       // The period of field synchronization signal is long 
 parameter V_BACK = 31;      // The signal period at the trailing edge of field synchronization is long 
 parameter V_ACT = 480;      // Long field display period 
 parameter V_BLANK = V_FRONT+V_SYNC+V_BACK;        // The total period of field blank signal is long 
 parameter V_TOTAL = V_FRONT+V_SYNC+V_BACK+V_ACT;  // The total period of the field is long and time-consuming 
 reg [10:0] H_Cont;        // Line cycle counter 
 reg [10:0] V_Cont;        // Field period counter 
 wire [7:0] VGA_R;         //VGA Red control line 
 wire [7:0] VGA_G;         //VGA Green control line 
 wire [7:0] VGA_B;         //VGA Blue control line 
 reg VGA_HS;
 reg VGA_VS;
 reg [10:0] X;             // The number of pixels in the current line 
 reg [10:0] Y;             // Which line of the current field 
 reg CLK_25;
 [email protected](posedge OSC_50)
    begin 
      CLK_25=~CLK_25;         // The clock 
    end 
    assign VGA_SYNC = 1'b0;   // Synchronization signal low level 
    assign VGA_BLANK = ~((H_Cont<H_BLANK)||(V_Cont<V_BLANK));  // When the row counter is less than the total length of the row blank or the field counter is less than the total length of the field blank , Blank signal low level 
    assign VGA_CLK = ~CLK_to_DAC;  //VGA The clock is equal to CLK_25 Take the opposite 
    assign CLK_to_DAC = CLK_25;
 [email protected](posedge CLK_to_DAC)
    begin
        if(H_Cont<H_TOTAL)           // If the row counter is less than the total row time 
            H_Cont<=H_Cont+1'b1;      // Row counter +1
        else H_Cont<=0;              // Otherwise, the line counter is cleared 
        if(H_Cont==H_FRONT-1)        // If the row counter is equal to the blank time at the leading edge of the row -1
            VGA_HS<=1'b0;             // The line synchronization signal is set to 0
        if(H_Cont==H_FRONT+H_SYNC-1) // If the row counter is equal to the row leading edge + Line synchronization -1
            VGA_HS<=1'b1;             // The line synchronization signal is set to 1
        if(H_Cont>=H_BLANK)          // If the row counter is greater than or equal to the total length of row blank 
            X<=H_Cont-H_BLANK;        //X Equal to the row counter - Total length of blank lines    （X Is the number of pixels in the current line ）
        else X<=0;                   // otherwise X by 0
    end
 [email protected](posedge VGA_HS)
    begin
        if(V_Cont<V_TOTAL)           // If the field counter is less than the total row time 
            V_Cont<=V_Cont+1'b1;      // Field counter +1
        else V_Cont<=0;              // Otherwise, the field counter is cleared 
        if(V_Cont==V_FRONT-1)       // If the field counter is equal to the field leading edge blank time -1
            VGA_VS<=1'b0;             // The field synchronization signal is set to 0
        if(V_Cont==V_FRONT+V_SYNC-1) // If the field counter is equal to the leading edge of the row + Field synchronization -1
            VGA_VS<=1'b1;             // The field synchronization signal is set to 1
        if(V_Cont>=V_BLANK)          // If the field counter is greater than or equal to the total time of field blank 
            Y<=V_Cont-V_BLANK;        //Y Equal to the field counter - Total duration of field blank     （Y For the line number of the current field ）  
        else Y<=0;                   // otherwise Y by 0
    end
    reg valid_yr;
 [email protected](posedge CLK_to_DAC)
    if(V_Cont == 10'd32)         // Field counter =32 when 
        valid_yr<=1'b1;           // Line input activates 
    else if(V_Cont==10'd512)     // Field counter =512 when 
        valid_yr<=1'b0;           // Line input freeze 
    wire valid_y=valid_yr;       // attachment    
    reg valid_r;            
 [email protected](posedge CLK_to_DAC)   
    if((H_Cont == 10'd32)&&valid_y)     // Row counter =32 when 
        valid_r<=1'b1;                   // Pixel input active 
    else if((H_Cont==10'd512)&&valid_y) // Row counter =512 when  
        valid_r<=1'b0;                   // Pixel input is frozen 
    wire valid = valid_r;               // attachment 
    wire[10:0] x_dis;     // Pixel display control signal 
    wire[10:0] y_dis;     // The line shows the control signal 
    assign x_dis=X;       // attachment X
    assign y_dis=Y;       // attachment Y
        parameter  // Dot matrix font ： Every line char_lineXX Is a line displayed , common 272 Column 
		  
char_line00=272'h0000000000000000000000000000000000000000000000000000000000000000000,
char_line01=272'h0000000000000000000000000000000000000000000000000000000000000000000,
char_line02=272'h0100001000020000020000000000000000000000000000000000000000000000000,
char_line03=272'h00C0001C00030000030000F00000000000000000000000000000000000000000000,
char_line04=272'h006000180001800002001FC00000000000000000000000000000000000000000000,
char_line05=272'h00700018000180000203E0000000000000000000000000000000000000000000000,
char_line06=272'h0030001800008010021000180000000003C00060008000600000000000000000000,
char_line07=272'h00200618000080387FF818180000000006200060018000600000000000000000000,
char_line08=272'h002186183FFFFFFC02020C30000000000C3000E01F8000E00000000000000000000,
char_line09=272'h3FFFC61800200C0002010C3000000000181800E0018000E00000000000000000000,
char_line0a=272'h0006061800200C00020184200000000018180160018001600000000000000000000,
char_line0b=272'h0007061800200C00022184400000000018080160018001600000000000000000000,
char_line0c=272'h0006061800100C003FF0808000000000300C0260018002600000000000000000000,
char_line0d=272'h080C0618001018000200000000000000300C0460018004600000000000000000000,
char_line0e=272'h040C0618001018000200180000000000300C0460018004600000000000000000000,
char_line0f=272'h020C06180018180002027FFC00000000300C0860018008600000000000000000000,
char_line10=272'h01980618000830000209801800000000300C0860018008600000000000000000000,
char_line11=272'h00D80618000C30007FFD001800000000300C1060018010600000000000000000000,
char_line12=272'h00700618000460000219001800000000300C3060018030600000000000000000000,
char_line13=272'h00380618000660000219001800000000300C2060018020600000000000000000000,
char_line14=272'h007C06180002C0000219101800000000300C4060018040600000000000000000000,
char_line15=272'h00CE06180003C0000211F9F800000000300C7FFC01807FFC0000000000000000000,
char_line16=272'h00C7061800018000021100180000000018080060018000600000000000000000000,
char_line17=272'h018386180003C00002B100180000000018180060018000600000000000000000000,
char_line18=272'h030380180006E000027100180000000018180060018000600000000000000000000,
char_line19=272'h06018018000C780002210018000000000C300060018000600000000000000000000,
char_line1a=272'h0C00001800381E0002010018000000000620006003C000600000000000000000000,
char_line1b=272'h1000001800600FC00201FFF80000000003C003FC1FF803FC0000000000000000000,
char_line1c=272'h200001F8018003FC020100180000000000000000000000000000000000000000000,
char_line1d=272'h400000700E0000F0020100180000000000000000000000000000000000000000000,
char_line1e=272'h0000002030000000020200000000000000000000000000000000000000000000000,
char_line1f=272'h0000000000000000000000000000000000000000000000000000000000000000000;
	  
    reg[8:0] char_bit;
    [email protected](posedge CLK_to_DAC)
        if(X==10'd144)char_bit<=9'd272;   // When displayed to 144 Pixel ready to start outputting image data 
        else if(X>10'd144&&X<10'd416)     // Left margin screen 144 Pixels to 416 When the pixel     416=144+272（ The width of the image ）
            char_bit<=char_bit-1'b1;       // Output image information upside down  
        reg[29:0] vga_rgb;                // Define color cache 
    [email protected](posedge CLK_to_DAC) 
		  
        if(X>10'd144&&X<10'd416)    //X Controls the horizontal display boundary of the image ： Left margin to the left of the screen 144 Pixels    The right boundary is away from the left boundary of the screen 416 Pixels 
            begin 
				//case(Y)
					 vga_rgb<=30'b1111111111_1111111111_0000000000;                            //Y Controls the vertical display boundary of the image ： From the top of the screen 160 Pixels begin to display the first row of data 
					 /*
                10'd160:
                if(char_line00[char_bit])vga_rgb<=30'b1111111111_1111111111_0000000000;  // If the row has data   The color is red 
                else vga_rgb<=30'b0000000000_0000000000_0000000000;                      // Otherwise black 
                10'd162:
                if(char_line01[char_bit])vga_rgb<=30'b1111111111_1111111111_0000000000;
                else vga_rgb<=30'b0000000000_0000000000_0000000000;
                10'd163:
                if(char_line02[char_bit])vga_rgb<=30'b1111111111_1111111111_0000000000;
                else vga_rgb<=30'b0000000000_0000000000_0000000000;
                10'd164:
                if(char_line03[char_bit])vga_rgb<=30'b1111111111_1111111111_0000000000;
                else vga_rgb<=30'b0000000000_0000000000_0000000000;
                10'd165:
                if(char_line04[char_bit])vga_rgb<=30'b1111111111_1111111111_0000000000;
                else vga_rgb<=30'b0000000000_0000000000_0000000000; 
                10'd166:
                if(char_line05[char_bit])vga_rgb<=30'b1111111111_1111111111_0000000000;
                else vga_rgb<=30'b0000000000_z0000000000_0000000000;
                10'd167:
                if(char_line06[char_bit])vga_rgb<=30'b1111111111_1111111111_0000000000;
                else vga_rgb<=30'b0000000000_0000000000_0000000000; 
                10'd168:
                if(char_line07[char_bit])vga_rgb<=30'b1111111111_1111111111_0000000000;
                else vga_rgb<=30'b0000000000_0000000000_0000000000;
                10'd169:
                if(char_line08[char_bit])vga_rgb<=30'b1111111111_1111111111_0000000000;
                else vga_rgb<=30'b0000000000_0000000000_0000000000; 
                10'd170:
                if(char_line09[char_bit])vga_rgb<=30'b1111111111_1111111111_0000000000;
                else vga_rgb<=30'b0000000000_0000000000_0000000000;
                10'd171:
                if(char_line0a[char_bit])vga_rgb<=30'b1111111111_1111111111_0000000000;
                else vga_rgb<=30'b0000000000_0000000000_0000000000;
                10'd172:
                if(char_line0b[char_bit])vga_rgb<=30'b1111111111_1111111111_0000000000;
                else vga_rgb<=30'b0000000000_0000000000_0000000000;
                10'd173:
                if(char_line0c[char_bit])vga_rgb<=30'b1111111111_1111111111_0000000000;
                else vga_rgb<=30'b0000000000_0000000000_0000000000;
                10'd174:
                if(char_line0d[char_bit])vga_rgb<=30'b1111111111_1111111111_0000000000;
                else vga_rgb<=30'b0000000000_0000000000_0000000000;
                10'd175:
                if(char_line0e[char_bit])vga_rgb<=30'b1111111111_1111111111_0000000000;
                else vga_rgb<=30'b0000000000_0000000000_0000000000;
                10'd176:
                if(char_line0f[char_bit])vga_rgb<=30'b1111111111_1111111111_0000000000;
                else vga_rgb<=30'b0000000000_0000000000_0000000000;
                10'd177:
                if(char_line10[char_bit])vga_rgb<=30'b1111111111_1111111111_0000000000;
                else vga_rgb<=30'b0000000000_0000000000_0000000000;
                10'd178:
                if(char_line11[char_bit])vga_rgb<=30'b1111111111_1111111111_0000000000;
                else vga_rgb<=30'b0000000000_0000000000_0000000000;
                10'd179:
                if(char_line12[char_bit])vga_rgb<=30'b1111111111_1111111111_0000000000;
                else vga_rgb<=30'b0000000000_0000000000_0000000000;
                10'd180:
                if(char_line13[char_bit])vga_rgb<=30'b1111111111_1111111111_0000000000;
                else vga_rgb<=30'b0000000000_0000000000_0000000000;
                10'd181:
                if(char_line14[char_bit])vga_rgb<=30'b1111111111_1111111111_0000000000;
                else vga_rgb<=30'b0000000000_0000000000_0000000000;
                10'd182:
                if(char_line15[char_bit])vga_rgb<=30'b1111111111_1111111111_0000000000;
                else vga_rgb<=30'b0000000000_0000000000_0000000000;
                10'd183:
                if(char_line16[char_bit])vga_rgb<=30'b1111111111_1111111111_0000000000;
                else vga_rgb<=30'b0000000000_0000000000_0000000000;
                10'd184:
                if(char_line17[char_bit])vga_rgb<=30'b1111111111_1111111111_0000000000;
                else vga_rgb<=30'b0000000000_0000000000_0000000000;
                10'd185:
                if(char_line18[char_bit])vga_rgb<=30'b1111111111_1111111111_0000000000;
                else vga_rgb<=30'b0000000000_0000000000_0000000000;
                10'd186:
                if(char_line19[char_bit])vga_rgb<=30'b1111111111_1111111111_0000000000;
                else vga_rgb<=30'b0000000000_0000000000_0000000000;
                10'd187:
                if(char_line1a[char_bit])vga_rgb<=30'b1111111111_1111111111_0000000000;
                else vga_rgb<=30'b0000000000_0000000000_0000000000;
                10'd188:
                if(char_line1b[char_bit])vga_rgb<=30'b1111111111_1111111111_0000000000;
                else vga_rgb<=30'b0000000000_0000000000_0000000000;
                10'd189:
                if(char_line1c[char_bit])vga_rgb<=30'b1111111111_1111111111_0000000000;
                else vga_rgb<=30'b0000000000_0000000000_0000000000;
                10'd190:
                if(char_line1d[char_bit])vga_rgb<=30'b1111111111_1111111111_0000000000;
                else vga_rgb<=30'b0000000000_0000000000_0000000000;
                10'd191:
                if(char_line1e[char_bit])vga_rgb<=30'b1111111111_1111111111_0000000000;
                else vga_rgb<=30'b0000000000_0000000000_0000000000;
                10'd192:
                if(char_line1f[char_bit])vga_rgb<=30'b1111111111_1111111111_0000000000;
                else vga_rgb<=30'b0000000000_0000000000_0000000000;
                default:vga_rgb<=30'h0000000000;   // Default color black 
            endcase
			*/	
        end
    else vga_rgb<=30'b1111111111_0000000000_1111111111;             // Otherwise black 
    assign VGA_R=vga_rgb[23:16];
    assign VGA_G=vga_rgb[15:8];
    assign VGA_B=vga_rgb[7:0];
endmodule

Use Chinese character dot matrix to replace Chinese characters in Chinese character code , Then implement VGA Show