基于FPGA的五子棋游戏设计

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)begin
	if(!rst_n)begin
      	hcount <= 10'd0;
	 end
    else if(hcount == 10'd799)begin
        hcount <= 10'd0;
     end
    else begin
	    hcount <= hcount+1'b1;
     end
 end

 always@(posedge vga_clk or negedge rst_n)begin
	if(!rst_n) begin
       vcount <= 10'd0;
    end
    else if(hcount == 10'd799)begin
        if(vcount==524)
            vcount <= 0;
        else
            vcount <= vcount+1;
    end
 end
	
always@(posedge vga_clk or negedge rst_n)begin
    if(!rst_n)begin
        hsync <= 1;
    end
    else if(hcount==10'd95)begin
        hsync <= 1'b1;
    end
    else if(hcount==10'd799)begin
        hsync <= 1'b0;
    end
end

always@(posedge vga_clk or negedge rst_n)begin
    if(!rst_n)begin
        vsync <= 1'b1;
    end
    else if(vcount<10'd2)begin
        vsync <= 1'b0;
    end
    else begin
        vsync <= 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 )
begin
    if(hcount<=200||hcount>=640)begin
    v_flag <= 1'b1 ;    
	v_dat <= 12'h000;//hei
    end else if(hcount ==240||hcount ==280||hcount ==320||hcount ==360||hcount ==400||hcount ==440||hcount ==480||hcount ==520||hcount==560||hcount==600) begin
    v_flag <= 1'b1 ;    
      v_dat <= 12'h000;//hei
   end else begin
    v_flag <= 1'b0 ;    
     v_dat <= 12'hfff;//bai
     end
end

//产生横长条
always@(posedge vga_clk )
begin
    if(vcount<=50||vcount>=490) begin
    h_flag <= 1'b1 ;
	h_dat <= 12'h000;//hei
    end else if(vcount ==90||vcount ==130||vcount ==170||vcount==210 ||vcount==250||vcount ==290||vcount ==330||vcount==370 ||vcount==410||vcount==450) begin
    h_flag <= 1'b1 ;    
      h_dat <= 12'h000;
   end else begin
    h_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)begin
  if(over==0 && over2==0  &&   debug_flag==0    ) begin
    if(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;    //  
    else
     disp_rgb <=12'hfff;    //   
  end else
   disp_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)begin
    if(!rst_n)begin
        PLAYED[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;  
    end
    else
begin
    case(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;
                    end
         5'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;                                                
                                                 end
       5'b00010: begin
                                           if(ball_y_pos== 10'd450)
                                           ball_y_pos<=10'd90;
                                           else         
                                           ball_y_pos<=ball_y_pos+10'd40; 
                                           end      
       5'b10000: begin
                                         if(PLAYED[current_y][current_x]==0)
                                          begin
                                              PLAYED[current_y][current_x]<=1;                                     
CHESS_COLOR[current_y][current_x]<=change_color;
                                          end
                                           end     

(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)begin
    over<=0; 
    end
    else
begin
    if (  (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)       )     
    begin
    over<=1;
    end
    else 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) )
    begin
    over<=1;
    end
    else 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)begin
    over2<=0;    
    debug_flag<=0;   
    end
    else
begin
    if( (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) )
    begin
    over2<=1;
    debug_flag<=1;  
    end
    else 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 )
begin
    if(((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))begin
    z_flag <= 1'b1;
    if(over)
	z_dat <= 12'hf0f;
    else
	z_dat <= 12'hff0;    
    end else if(hcount>=260&&hcount<=380&&vcount>=340&&vcount <=360) begin
    z_flag <= 1'b1;
    if(over)
	z_dat <= 12'hf0f;
    else
	z_dat <= 12'hff0;    
     end else if(hcount>=500&&hcount<=560&&vcount>=200&&vcount <=220) begin
      z_flag <= 1'b1;
    if(over)
	z_dat <= 12'hf0f;
    else
	z_dat <= 12'hff0;    
    end else begin
        z_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)
begin
    vga_clk <= ~vga_clk;
end   
优化后的：
    pll pll(
	.inclk0(sysclk),
	.c0(vga_clk)
);