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VGA的全称是Video Graphics Array,即视频图形阵列,是一个使用模拟信号进行视频传
输的标准。早期的CRT显示器由于设计制造上的原因,只能接收模拟信号输入,因此计算机内
部的显卡负责进行数模转换,而VGA接口就是显卡上输出模拟信号的接口。如今液晶显示器虽
然可以直接接收数字信号,但是为了兼容显卡上的VGA接口,也大都支持VGA标准。
VGA接口定义及各引脚功能说明如图 18.1.2所示,我们一般只用到其中的1(RED)、2
(GREEN)、3(BLUE)、13(HSYNC)、14(VSYNC)信号。引脚1、2、3分别输出红、绿、蓝三原
色模拟信号,电压变化范围为 0~0.714V,0V代表无色,0.714V 代表满色;引脚13、14输出TTL
电平标准的行/场同步信号。
程中的同步时序分为行时序和场时序:
不同分辨率的VGA时序参数
时钟频率 = 行帧长 × 列帧长 * 刷新率,640 ×480 60HZ对应时钟频率= 800 ×525 × 60 = 25.2M,因此需要用分频时钟来做或者手动设置二分频。
FPGA管脚输出的颜色数据位宽为16bit,数据格式为RGB565,即数据 高5位表示红色,中间6位表示绿色,低5位表示蓝色。RGB565格式的数据一共可表示65536种颜 色,此外常用的颜色数据格式还有RGB888,数据位宽越大,可以表示的颜色种类就越丰富。
分辨率控制部分:
```c `define vga_640_480 `define vga_1920_1080 `define vga_1024_768 `ifdef vga_640_480 //执行操作A `define H_Right_Border 8 `define H_Front_Porch 8 `define H_Sync_Time 96 `define H_Back_Porch 40 `define H_Left_Border 8 `define H_Data_Time 640 `define H_Total_Time 800 `define V_Bottom_Border 8 `define V_Front_Porch 2 `define V_Sync_Time 2 `define V_Back_Porch 25 `define V_Top_Border 8 `define V_Data_Time 480 `define V_Total_Time 525 `elsif vga_1920_1080 //执行操作B `define H_Right_Border 0 `define H_Front_Porch 88 `define H_Sync_Time 44 `define H_Back_Porch 148 `define H_Left_Border 0 `define H_Data_Time 1920 `define H_Total_Time 2200 `define V_Bottom_Border 0 `define V_Front_Porch 4 `define V_Sync_Time 5 `define V_Back_Porch 36 `define V_Top_Border 0 `define V_Data_Time 1080 `define V_Total_Time 1125 `elsif vga_1024_768 `define H_Right_Border 0 `define H_Front_Porch 24 `define H_Sync_Time 136 `define H_Back_Porch 160 `define H_Left_Border 0 `define H_Data_Time 1024 `define H_Total_Time 1344 `define V_Bottom_Border 0 `define V_Front_Porch 3 `define V_Sync_Time 6 `define V_Back_Porch 29 `define V_Top_Border 0 `define V_Data_Time 768 `define V_Total_Time 806 `else `endif
```c
VAG驱动
`define vga_640_480 `include "vga_para.v" module vga_ctrl( input clk ,//时钟信号 //25.2MHZ input rst_n ,//复位信号 input [23:0] data_disp , output reg [10:0] h_addr ,//数据有效显示区域行地址 output reg [10:0] v_addr ,//数据有效显示区域场地址 output reg vsync , output reg hsync , output reg [7 :0] vga_r , output reg [7 :0] vga_b , output reg [7 :0] vga_g , output wire vga_blk , output wire vga_sync , output reg vga_clk //25.2MHZ ); //参数定义 parameter H_SYNC_START = 1, H_SYNC_STOP = `H_Sync_Time , H_DATA_START = `H_Sync_Time + `H_Back_Porch + `H_Left_Border, H_DATA_STOP = `H_Sync_Time + `H_Back_Porch + `H_Left_Border + `H_Data_Time, V_SYNC_START = 1, V_SYNC_STOP = `V_Sync_Time, V_DATA_START = `V_Sync_Time + `V_Back_Porch + `V_Top_Border, V_DATA_STOP = `V_Sync_Time + `V_Back_Porch + `V_Top_Border + `V_Data_Time; //信号定义 reg [11:0] cnt_h_addr ;//行地址计数器 wire add_h_addr ; wire end_h_addr ; reg [11:0] cnt_v_addr ;//长地址计数器 wire add_v_addr ; wire end_v_addr ; assign vga_sync = 1'b0; assign vga_blk = ~((cnt_h_addr<`H_Front_Porch + `H_Sync_Time + `H_Back_Porch)||(cnt_v_addr<`V_Front_Porch + `V_Sync_Time + `V_Back_Porch)); always@(posedge vga_clk or negedge rst_n)begin if(!rst_n)begin cnt_h_addr <= 12'd0; end else if(add_h_addr)begin if(end_h_addr)begin cnt_h_addr <= 12'd0; end else begin cnt_h_addr <= cnt_h_addr + 12'd1; end end else begin cnt_h_addr <= 12'd0; end end assign add_h_addr = 1'b1; assign end_h_addr = add_h_addr && cnt_h_addr == `H_Total_Time - 1; always@(posedge vga_clk or negedge rst_n)begin if(!rst_n)begin cnt_v_addr <= 12'd0; end else if(add_v_addr)begin if(end_v_addr)begin cnt_v_addr <= 12'd0; end else begin cnt_v_addr <= cnt_v_addr + 12'd1; end end else begin cnt_v_addr <= cnt_v_addr; end end assign add_v_addr = end_h_addr; assign end_v_addr = add_v_addr && cnt_v_addr == `V_Total_Time - 1; //行场同步信号 always@(posedge vga_clk or negedge rst_n)begin if(!rst_n)begin hsync <= 1'b1; end else if(cnt_h_addr == H_SYNC_START - 1)begin hsync <= 1'b0; end else if(cnt_h_addr == H_SYNC_STOP - 1)begin hsync <= 1'b1; end else begin hsync <= hsync; end end always@(posedge vga_clk or negedge rst_n)begin if(!rst_n)begin vsync <= 1'b1; end else if(cnt_v_addr == V_SYNC_START - 1)begin vsync <= 1'b0; end else if(cnt_v_addr == V_SYNC_STOP - 1)begin vsync <= 1'b1; end else begin vsync <= vsync; end end always@(posedge clk or negedge rst_n)begin if(!rst_n)begin vga_clk =0; end else begin vga_clk = ~vga_clk; end end //数据有效显示区域定义 always@(posedge vga_clk or negedge rst_n)begin if(!rst_n)begin h_addr <= 11'd0; end else if((cnt_h_addr >= H_DATA_START - 1) &&( cnt_h_addr <= H_DATA_STOP - 1))begin h_addr <= cnt_h_addr - H_DATA_START - 1; end else begin h_addr <= 11'd0; end end always@(posedge vga_clk or negedge rst_n)begin if(!rst_n)begin v_addr <= 11'd0; end else if((cnt_v_addr >= V_DATA_START - 1) && (cnt_v_addr <= V_DATA_STOP - 1))begin v_addr <= cnt_v_addr - V_DATA_START -1; end else begin v_addr <= 11'd0; end end //显示数据 always@(posedge vga_clk or negedge rst_n)begin if(!rst_n)begin vga_r <= 8'b0; vga_g <= 8'b0; vga_b <= 8'b0; end else if((cnt_h_addr >= H_DATA_START - 1) &&( cnt_h_addr <= H_DATA_STOP - 1) && (cnt_v_addr >= V_DATA_START - 1) && (cnt_v_addr <= V_DATA_STOP - 1))begin vga_r <= data_disp[23:16]; vga_g <= data_disp[15: 8]; vga_b <= data_disp[7 : 0]; end else begin vga_r <= 8'b0; vga_g <= 8'b0; vga_b <= 8'b0; end end endmodule
颜色显示:
module data_gen( input clk ,//时钟信号 input rst_n ,//复位信号 input [10:0] h_addr ,//数据有效显示区域地址 input [10:0] v_addr ,//数据有效显示区域地址 output reg [23:0] data_disp ); //参数定义 parameter BLACK = 24'h000000, RED = 24'hFF0000, GREEN = 24'h00FF00, BLUE = 24'h0000FF, YELLOW = 24'hFFFF00, SKY_BULE = 24'h00FFFF, PURPLE = 24'hFF00FF, GREY = 24'hC0C0C0, WIGHT = 24'hFFFFFF; always@(posedge clk or negedge rst_n)begin if(!rst_n)begin data_disp <= BLACK; end else begin case(h_addr) 0 : data_disp <= RED; 80 : data_disp <= GREEN; 160: data_disp <= BLUE; 240: data_disp <= YELLOW; 320: data_disp <= SKY_BULE; 400: data_disp <= PURPLE; 480: data_disp <= GREY; 560: data_disp <= WIGHT; default:data_disp <= data_disp; endcase end end endmodule
顶层模块:
module vga_top( input clk ,//时钟信号 input rst_n ,//复位信号 output wire vsync , output wire hsync , output wire [7 :0] vga_r , output wire [7 :0] vga_b , output wire [7 :0] vga_g , output vga_blk , output wire vga_sync , output vga_clk ); wire [23:0] data_disp ; wire [10:0] h_addr ; wire [10:0] v_addr ; data_gen u_data_gen( .clk (vga_clk ),//时钟信号 .rst_n (rst_n ),//复位信号 .h_addr (h_addr ),//数据有效显示区域地址 .v_addr (v_addr ),//数据有效显示区域地址 .data_disp (data_disp ) ); vga_ctrl u_vga_ctrl( .clk (clk ),//时钟信号 25.2MHZ .rst_n (rst_n ),//复位信号 .data_disp (data_disp ), .h_addr (h_addr ),//数据有效显示区域行地址 .v_addr (v_addr ),//数据有效显示区域场地址 .vsync (vsync ), .hsync (hsync ), .vga_r (vga_r ), .vga_b (vga_b ), .vga_g (vga_g ), .vga_blk (vga_blk ), .vga_sync (vga_sync ), .vga_clk (vga_clk ) ); endmodule
结果显示:
这里需要显示字符,需要用到汉字点阵工具,在这里我们使用取模软件“PCtoLCD2002”来获
取汉字“正点原子”的字模
姓名:
另存为bmp文件,再点击文件打开bpm文件,进入图像模式
生成字模:
{0020002000202020FC501020105013FE},
{108882221124422412124A207C100BFC},
{11FC1284100412881008E24810882250},
{1C502220E02024504010248800100906}
最终得到
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
代码部分:
module vga_driver( 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=240'h0020002000200000000000000000000000000000000000000000000000000000, char_line01=240'h7E20002020200000000000000000000000000000000000000000000000000000, char_line02=240'h0220FC5010200000000000000000000000000000000000000000000000000000, char_line03=240'h0420105013FE000007F00FE000800FE007E01FFC07E007F007E007F000801FFC, char_line04=240'h0820108882220000081830180780301818183008181808181818081807803008, char_line05=240'h08A8112442240000100038180180300C381C2010381C1000381C100001802010, char_line06=240'h0AA412124A200000300000180180700C300C0020300C3000300C300001800020, char_line07=240'h0CA47C100BFCFFFF37F000600180301C300C0040300C37F0300C37F001800040, char_line08=240'h392211FC12840000380C01F00180382C300C0080300C380C300C380C01800080, char_line09=240'hC922100412880000300C001801800FCC300C0180300C300C300C300C01800180, char_line0a=240'h0A221008E2480000300C000C0180001C300C0300300C300C300C300C01800300, char_line0b=240'h0820108822500000300C380C01800018381803003818300C3818300C01800300, char_line0c=240'h08201C502220000018183018018038301C1003801C1018181C10181801800380, char_line0d=240'h0820E0202450000007E00FE00FF80FC007E0030007E007E007E007E00FF80300, char_line0e=240'h28A0401024880000000000000000000000000000000000000000000000000000, char_line0f=240'h1040001009060000000000000000000000000000000000000000000000000000; reg[7:0] char_bit; always@(posedge CLK_to_DAC) if(X==10'd144)char_bit<=9'd240; //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'd384) //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'd384) //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; 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
结果如下:
由于一张640×480的24位的图片的大小超过了芯片的内存,无法把图片保存进去,故采用一张128*78的图片进行显示。
原图:
转换得到HEX文件
调用rom核来完成
设置位宽度为16位,大小为图片大小128×78 = 9984
取消勾选:
找到刚才生成的data1.hex文件
result:
`
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