基于FPGA的五子棋游戏设计
本文基于FPGA设计五子棋游戏，使用按键输入，使用VGA接口输出。五子棋的棋具与围棋相同，棋子分为黑白两色，棋盘为10×10，棋子放置于棋盘线交叉点上。两人对局，各执一色，轮流下一子，先将横、竖或斜线的5个或5个以上同色棋子连成不间断的一排者为胜。
VGA技术介绍：
VGA 接口就是显卡上输出模拟信号的接口，也叫 D-Sub 接口。VGA 接口是一种 D
型口，上面共有 15 针空，分成三排，每排五个。VGA 接口是目前中低端电脑配置上的主流口。
VGA显示中，FPGA需要产生5个信号：R、G、B三基色信号，行同步信号HS，场同步信号VS。以上接口的5个孔对应着我们FPGA中产生的5个重要的信号，其中R、G、B是数据信号；HS、VS是控制信号。下面是VGA 显示模块与CRT 显示器的控制框图：
像素是产生各种颜色的基本单元。根据物理学中的混色原理，三色发光的亮度比例适当，可呈现白色。适当的调整发光比例可以出现不同的颜色。三基色混色原理示意图如下图所示：
对于显示器来说，RGB三个信号其实是模拟信号，其电平的高低，可以表示颜色的深浅。利用这个原理，我们就可以产生丰富的色彩。为了控制电压的高低，我们就必须用到DA芯片。例如下图中，FPGA产生RGB三种信号，这时RGB都是多位的数字信号。DA芯片根据数字信号的值，产生不同电压的模拟信号rgb。
DE1-SoC板上有一个15针D-SUB连接器，用于VGA输出。VGA同步信号直接从Cyclone V SoC FPGA和Analog器件ADV7123三路10位高速视频DAC（仅使用较高的8位）转换从数字到模拟的信号代表三种基本颜色（红色，绿色和蓝色）。 它可以支持高达SXGA标准（1280 * 1024），信号以100MHz传输。 下图显示FPGA和VGA之间连接的信号。
显示器采用光栅扫描方式，即轰击荧光屏的电子束在 CRT 屏幕上从左到右（受水平同步信号 HSYNC 控制）、从上到下（受垂直同步信号 VSYNC 控制）做有规律的移动。电子束采用光栅扫描方式，从屏幕左上角一点开始，向右逐点进行扫描，形成一条水平线；到达最右端后，又回到下一条水平线的左端，重复上面的过程；当电子束完成右下角一点的扫描后，形成一帧。此后，电子束又回到左上方起点，开始下一帧的扫描。这种方法也就是常说的逐行扫描显示。
完成一行扫描的时间称为水平扫描时间，其倒数称为行频率；完成一帧（整屏）扫描的时间称为垂直扫描时间，其倒数称为场频率，即刷新一屏的频率，常见的有60Hz，75Hz等等。标准的VGA显示的场频60Hz。
行时序和场时序都需要同步脉冲（Sync a）、显示后沿（Back porch b）、显示时序段（Display interval c）和显示前沿（Front porch d）四部分。VGA工业标准显示模式要求：行同步，场同步都为负极性，即同步脉冲要求是负脉冲。
VGA支持的规格
我们以第一个分辨率640/480来分析，其刷新速率是60Hz，每幅图像有525行，每行有800个值。也就是说完成一幅图像约是1s/60=16.6ms，完成一行约为16.6ms/525=31.75us，完成一个像素传送约来31.75us /800=40ns。因此为了方便设计，接口的时候设为25MHz最方便，每个时钟送一个数据。
VGA时序设计
根据上节的介绍，VGA时序要求如下
VGA时序代码设计
/**********VGA驱动**********/
always@(posedge vga_clk or negedge rst_n)beginif(!rst_n)beginhcount <= 10'd0;endelse if(hcount == 10'd799)beginhcount <= 10'd0;endelse beginhcount <= hcount+1'b1;endendalways@(posedge vga_clk or negedge rst_n)beginif(!rst_n) beginvcount <= 10'd0;endelse if(hcount == 10'd799)beginif(vcount==524)vcount <= 0;elsevcount <= vcount+1;endendalways@(posedge vga_clk or negedge rst_n)beginif(!rst_n)beginhsync <= 1;endelse if(hcount==10'd95)beginhsync <= 1'b1;endelse if(hcount==10'd799)beginhsync <= 1'b0;end
endalways@(posedge vga_clk or negedge rst_n)beginif(!rst_n)beginvsync <= 1'b1;endelse if(vcount<10'd2)beginvsync <= 1'b0;endelse beginvsync <= 1'b1;end
end
VGA时序仿真结果
五子棋设计
为了节约FPGA资源，本文设计并编写了10x10 五子棋的专用算法。棋子半径大小20个像素。光标当前的棋子所在位置使用青色表示，因为屏幕背景色是黑色，棋盘背景色是白色，所以黑白棋子使用紫色和黄色代替。
棋盘设计：
设10x10数组reg [9:0] PLAYED [9:0]; 数组中每一位代表棋盘的一个交叉点。数组的某位为0时，代表无子状态； 为l时，代表有棋子；
设10x10数组reg [9:0] CHESS_COLOR [9:0];表示棋子的颜色。
产生棋盘格的代码如下：
//产生竖长条
always@(posedge vga_clk )
beginif(hcount<=200||hcount>=640)beginv_flag <= 1'b1 ; v_dat <= 12'h000;//heiend else if(hcount ==240||hcount ==280||hcount ==320||hcount ==360||hcount ==400||hcount ==440||hcount ==480||hcount ==520||hcount==560||hcount==600) beginv_flag <= 1'b1 ; v_dat <= 12'h000;//heiend else beginv_flag <= 1'b0 ; v_dat <= 12'hfff;//baiend
end//产生横长条
always@(posedge vga_clk )
beginif(vcount<=50||vcount>=490) beginh_flag <= 1'b1 ;h_dat <= 12'h000;//heiend else if(vcount ==90||vcount ==130||vcount ==170||vcount==210 ||vcount==250||vcount ==290||vcount ==330||vcount==370 ||vcount==410||vcount==450) beginh_flag <= 1'b1 ; h_dat <= 12'h000;end else beginh_flag <= 1'b0 ; h_dat <= 12'hfff;end
end
2)当前棋子光标提示设计：
当前棋子位置提示显示数据为x_data,显示青色。V_dat和H_dat是横竖线的，显示为黑色，y_dat为棋子颜色。
/
/显示模块
always@(posedge vga_clk)
begin
if(dat_act)beginif(over==0 && over2==0 && debug_flag==0 ) beginif(curchess_flag)disp_rgb <=x_dat; // else if(v_flag)disp_rgb <=v_dat; // else if(h_flag)disp_rgb <=h_dat; // else if(chess_flag)disp_rgb <=y_dat; // elsedisp_rgb <=12'hfff; // end elsedisp_rgb <=z_dat; //游戏结束则显示另外画面
end
else begin
disp_rgb = 12'h000; //VGA区域之外
end
end
3)按钮上、下、左、右、落子：
always@(posedge sysclk or negedge rst_n)beginif(!rst_n)beginPLAYED[0]<=10'd0; PLAYED[1]<=10'd0; PLAYED[2]<=10'd0; PLAYED[3]<=10'd0; PLAYED[4]<=10'd0; PLAYED[5]<=10'd0; PLAYED[6]<=10'd0; PLAYED[7]<=10'd0; PLAYED[8]<=10'd0; PLAYED[9]<=10'd0; CHESS_COLOR[0]<=10'd0; CHESS_COLOR[1]<=10'd0; CHESS_COLOR[2]<=10'd0; CHESS_COLOR[3]<=10'd0; CHESS_COLOR[4]<=10'd0; CHESS_COLOR[5]<=10'd0; CHESS_COLOR[6]<=10'd0; CHESS_COLOR[7]<=10'd0; CHESS_COLOR[8]<=10'd0; CHESS_COLOR[9]<=10'd0; endelse
begincase(key_en_tem)5'b00100:begin if (ball_x_pos== 10'd240)ball_x_pos<=10'd600;else ball_x_pos<=ball_x_pos-10'd40;end5'b01000:begin if (ball_x_pos==10'd600)ball_x_pos<=10'd240;else ball_x_pos<= ball_x_pos+10'd40;end 5'b00001: begin if (ball_y_pos== 10'd90)ball_y_pos<=10'd450;else ball_y_pos<=ball_y_pos-10'd40; end5'b00010: beginif(ball_y_pos== 10'd450)ball_y_pos<=10'd90;else ball_y_pos<=ball_y_pos+10'd40; end 5'b10000: beginif(PLAYED[current_y][current_x]==0)beginPLAYED[current_y][current_x]<=1;
CHESS_COLOR[current_y][current_x]<=change_color;endend
(4)判胜：
横竖正斜反斜四个方向出现连续落子，且颜色一样，输出胜利提示。
```c
//输赢状态判断1
always@(posedge vga_clk )if(!rst_n)beginover<=0; endelse
beginif ( (scan_x<=5&&CHESS_COLOR[scan_y][scan_x]==1&&CHESS_COLOR[scan_y][scan_x+1]==1&&CHESS_COLOR[scan_y][scan_x+2]==1&&CHESS_COLOR[scan_y][scan_x+3]==1&&CHESS_COLOR[scan_y][scan_x+4]==1)//heng&& (PLAYED[scan_y][scan_x]==1&&PLAYED[scan_y][scan_x+1]==1&&PLAYED[scan_y][scan_x+2]==1&&PLAYED[scan_y][scan_x+3]==1&&PLAYED[scan_y][scan_x+4]==1) ) beginover<=1;endelse if( (scan_y<=5&&CHESS_COLOR[scan_y][scan_x]==1&&CHESS_COLOR[scan_y+1][scan_x]==1&&CHESS_COLOR[scan_y+2][scan_x]==1&&CHESS_COLOR[scan_y+3][scan_x]==1&&CHESS_COLOR[scan_y+4][scan_x]==1)//shu&& (PLAYED[scan_y][scan_x]==1&&PLAYED[scan_y+1][scan_x]==1&&PLAYED[scan_y+2][scan_x]==1&&PLAYED[scan_y+3][scan_x]==1&&PLAYED[scan_y+4][scan_x]==1) )beginover<=1;endelse if( (scan_x<=5&&scan_y<=5&&CHESS_COLOR[scan_y][scan_x]==1&&CHESS_COLOR[scan_y+1][scan_x+1]==1&&CHESS_COLOR[scan_y+2][scan_x+2]==1&&CHESS_COLOR[scan_y+3][scan_x+3]==1&&CHESS_COLOR[scan_y+4][scan_x+4]==1)//chenggong&& (PLAYED[scan_y][scan_x]==1&&PLAYED[scan_y+1][scan_x+1]==1&&PLAYED[scan_y+2][scan_x+2]==1&&PLAYED[scan_y+3][scan_x+3]==1&&PLAYED[scan_y+4][scan_x+4]==1) )over<=1;else if ( (scan_y<=5&&scan_x>=4&&CHESS_COLOR[scan_y][scan_x]==1&&CHESS_COLOR[scan_y+1][scan_x-1]==1&&CHESS_COLOR[scan_y+2][scan_x-2]==1&&CHESS_COLOR[scan_y+3][scan_x-3]==1&&CHESS_COLOR[scan_y+4][scan_x-4]==1)&& (PLAYED[scan_y][scan_x]==1&&PLAYED[scan_y+1][scan_x-1]==1&&PLAYED[scan_y+2][scan_x-2]==1&&PLAYED[scan_y+3][scan_x-3]==1&&PLAYED[scan_y+4][scan_x-4]==1) )over<=1;
end
```c
//输赢状态判断2 yellow
always@(posedge vga_clk )if(!rst_n)beginover2<=0; debug_flag<=0; endelse
beginif( (scan_x<=5&&CHESS_COLOR[scan_y][scan_x]==0&&CHESS_COLOR[scan_y][scan_x+1]==0&&CHESS_COLOR[scan_y][scan_x+2]==0&&CHESS_COLOR[scan_y][scan_x+3]==0&&CHESS_COLOR[scan_y][scan_x+4]==0)//heng&& (PLAYED[scan_y][scan_x]==1&&PLAYED[scan_y][scan_x+1]==1&&PLAYED[scan_y][scan_x+2]==1&&PLAYED[scan_y][scan_x+3]==1&&PLAYED[scan_y][scan_x+4]==1) ) over2<=1;else if( (scan_y<=5&&CHESS_COLOR[scan_y][scan_x]==0&&CHESS_COLOR[scan_y+1][scan_x]==0&&CHESS_COLOR[scan_y+2][scan_x]==0&&CHESS_COLOR[scan_y+3][scan_x]==0&&CHESS_COLOR[scan_y+4][scan_x]==0)//shu&& (PLAYED[scan_y][scan_x]==1&&PLAYED[scan_y+1][scan_x]==1&&PLAYED[scan_y+2][scan_x]==1&&PLAYED[scan_y+3][scan_x]==1&&PLAYED[scan_y+4][scan_x]==1) )beginover2<=1;debug_flag<=1; endelse if( (scan_x<=5&&scan_y<=5&&CHESS_COLOR[scan_y][scan_x]==0&&CHESS_COLOR[scan_y+1][scan_x+1]==0&&CHESS_COLOR[scan_y+2][scan_x+2]==0&&CHESS_COLOR[scan_y+3][scan_x+3]==0&&CHESS_COLOR[scan_y+4][scan_x+4]==0)//chenggong&& (PLAYED[scan_y][scan_x]==1&&PLAYED[scan_y+1][scan_x+1]==1&&PLAYED[scan_y+2][scan_x+2]==1&&PLAYED[scan_y+3][scan_x+3]==1&&PLAYED[scan_y+4][scan_x+4]==1) )over2<=1;else if ( (scan_y<=5&&scan_x>=4&&CHESS_COLOR[scan_y][scan_x]==0&&CHESS_COLOR[scan_y+1][scan_x-1]==0&&CHESS_COLOR[scan_y+2][scan_x-2]==0&&CHESS_COLOR[scan_y+3][scan_x-3]==0&&CHESS_COLOR[scan_y+4][scan_x-4]==0)&& (PLAYED[scan_y][scan_x]==1&&PLAYED[scan_y+1][scan_x-1]==1&&PLAYED[scan_y+2][scan_x-2]==1&&PLAYED[scan_y+3][scan_x-3]==1&&PLAYED[scan_y+4][scan_x-4]==1) )over2<=1;
end
(5)win画面：在任一方胜利后VGA显示win三个字母画面输出胜利提示。根据棋子颜色win显示不同颜色以显示
//产生win画面1
always@(posedge vga_clk )
beginif(((hcount>=240&&hcount<=260)||(hcount>=300&&hcount<=320)||(hcount>=360&&hcount<=380)||(hcount>=420&&hcount<=440)||(hcount>=480&&hcount<=500)||(hcount>=560&&hcount<=580))&&(vcount >=200&&vcount <=360))beginz_flag <= 1'b1;if(over)z_dat <= 12'hf0f;elsez_dat <= 12'hff0; end else if(hcount>=260&&hcount<=380&&vcount>=340&&vcount <=360) beginz_flag <= 1'b1;if(over)z_dat <= 12'hf0f;elsez_dat <= 12'hff0; end else if(hcount>=500&&hcount<=560&&vcount>=200&&vcount <=220) beginz_flag <= 1'b1;if(over)z_dat <= 12'hf0f;elsez_dat <= 12'hff0; end else beginz_flag <= 1'b0;z_dat <= 12'hfff;end
end
遇到的问题：
1 棋子颜色显示不稳定，下棋时棋子颜色随机产生不受控制。原因怀疑是时钟一开始是分频产生的25M，后面换成pll锁相环后问题果然解决。
一开始的时钟产生方法：
always@(posedge sysclk)
beginvga_clk <= ~vga_clk;
end
优化后的：pll pll(.inclk0(sysclk),.c0(vga_clk)
);
