PS2键盘 + LCD12864 实验

本实验是通过LCD12864来显示键盘上被按下的按键，实验比较简单，在LCD12864固定的DDRAM地址上显示，缺点就是不能保存上一次被按的内容，后者会覆盖掉前面，所以屏上仅有一个字符显示。保存上一次内容不被覆盖掉方法还待改进。目前将就这样吧。

关于LCD12864显示可以参考“LCD12864 液晶显示-汉字及自定义显示（并口）”，代码稍微改了一下，可以参考代码。

PS2键盘解码实验也比较简单，可以参考特权的或是“verilog HDL的那些事儿”也可以在网上找到相关的资料。

ps2_control.v

 module ps2_control(
                     //input
                     sys_clk,
                     rst_n,
                     key_clk,
                     key_data,

                     //output
                     data_buf,
                    );
 input sys_clk;    //50Mhz
 input rst_n;
 input key_clk;      //键盘时钟
 input key_data;   //键盘数据

 output [:] data_buf;    //保存要显示的数据

 //***********************************************
 //检测key_clk的下降沿
 //***********************************************
 reg key_clk_1;
 reg key_clk_2;
 always @(posedge sys_clk or negedge rst_n)
 if(!rst_n) begin
    key_clk_1 <= 'b1;
    key_clk_2 <= 'b1;
 end
 else begin
     key_clk_1 <= key_clk;
     key_clk_2 <= key_clk_1;
 end

 wire key_clk_n;
 assign key_clk_n = key_clk_2 & (~key_clk_1);
 //***********************************************
 //对key_data上的数据进行保存
 //***********************************************
 reg [:] i;
 reg [:] data_temp;
 always @(posedge sys_clk or negedge rst_n)
 if(!rst_n) begin
     i <= 'd0;
     data_temp <= 'h00;
 end
 else if(key_clk_n) begin
     case(i)
     'd0: i <= i + 1'b1;  //起始位不处理

     'd1,4'd2,'d3,4'd4,'d5,4'd6,'d7,4'd8:
     begin
         i <= i + 'b1;
         data_temp[i-] <= key_data;
     end

     'd9: i <= i + 1'b1;  //奇校验位不处理

     'd10: i <= 4'd0;    //停止位不处理

     default:    ;
     endcase
 end

 reg key_f0;        //松键标志位，置1表示接收到数据8'hf0，再接收到下一个数据后清零
 reg[:] ps2_data;
 always @(posedge sys_clk or negedge rst_n)    //接收数据的相应处理，这里只对1byte的键值进行处理
 if(!rst_n) begin
     key_f0 <= 'b0;
     ps2_data <= 'h00;
 end
 else if(i=='d10) //刚传送完一个字节数据
 begin
     if(data_temp == 'hf0)
         key_f0 <= 'b1;  //说明有键被释放
     else if(!key_f0)    //说明有键按下
         ps2_data <= data_temp;    //锁存当前键值
     else
         key_f0 <= 'b0;
 end

 reg [:] data_buf;
 always @ (ps2_data) begin
     case (ps2_data)
         'h15: data_buf = "Q";
         'h1d: data_buf = "W";
         'h24: data_buf = "E";
         'h2d: data_buf = "R";
         'h2c: data_buf = "T";
         'h35: data_buf = "Y";
         'h3c: data_buf = "U";
         'h43: data_buf = "I";
         'h44: data_buf = "O";
         'h4d: data_buf = "P";
         'h1c: data_buf = "A";
         'h1b: data_buf = "S";
         'h23: data_buf = "D";
         'h2b: data_buf = "F";
         'h34: data_buf = "G";
         'h33: data_buf = "H";
         'h3b: data_buf = "J";
         'h42: data_buf = "K";
         'h4b: data_buf = "L";
         'h1a: data_buf = "Z";
         'h22: data_buf = "X";
         'h21: data_buf = "C";
         'h2a: data_buf = "V";
         'h32: data_buf = "B";
         'h31: data_buf = "N";
         'h3a: data_buf = "M";
         default: data_buf = 'h00;
     endcase
 end

 endmodule

LCD12864.v

 module LCD12864(
                     //input
                     sys_clk,
                     rst_n,
                     data_buf,

                     //output
                     lcd_rs,
                     lcd_rw,
                     lcd_en,
                     lcd_data,
                     lcd_psb
                 );
 input sys_clk;// 50MHZ
 input rst_n;
 input [:] data_buf;

 output lcd_rs;//H:data    L:command
 output lcd_rw;//H:read module    L:write module
 output lcd_en;//H active
 output [:] lcd_data;
 output lcd_psb;//H:parallel    module    L:SPI module

 /***************************************************/
 parameter T3MS = 'd149_999;
 parameter    IDLE           = 'd0,
             INIT_FUN_SET1 = 'd1,
             INIT_FUN_SET2 = 'd2,
             INIT_DISPLAY  = 'd3,
             INIT_CLEAR       = 'd4,
             INIT_DOT_SET  = 'd5,
             SET_DDRAM      = 'd6,
             WRITE_DATA1      = 'd7;
 /*            INIT_FUN_SET3 = 4'd8,
             SET_CGRAM     = 4'd9,
             WRITE_DATA2   = 4'd10,
             SET_DDRAM2    = 4'd11,
             SET_CUSTOM_L  = 4'd12,
             SET_CUSTOM_H  = 4'd13,
             STOP          = 4'd14;*/
 /***************************************************/
 //产生周期为6MS的lcd_clk给LCD
 reg [:] cnt;
 reg lcd_clk;
 always @(posedge sys_clk or negedge rst_n)
 if(!rst_n) begin
     cnt <= 'd0;
     lcd_clk <= 'b0;
 end
 else if(cnt == T3MS)begin
     cnt <= 'd0;
     lcd_clk <= ~lcd_clk;
 end
 else
     cnt <= cnt + 'b1;

 /***************************************************/
 reg lcd_rs;
 always @(posedge lcd_clk or negedge rst_n)
 if(!rst_n)
     lcd_rs <= 'b0;
 else if(state == WRITE_DATA1)
     lcd_rs <= 'b1;        //写数据模式
 else
     lcd_rs <= 'b0;        //写命令模式
 /***************************************************/
 reg [:] state;
 reg [:] lcd_data;
 reg [:] num;
 reg en;
 always @(posedge lcd_clk or negedge rst_n)
 if(!rst_n) begin
     state <= IDLE;
     lcd_data <= 'h00;
     en <= 'b1;
     num <= 'd0;
 end
 else
     case(state)
         IDLE:
         begin
             state <= INIT_FUN_SET1;
             lcd_data <= 'hzz;
             en <= 'b1;
         end

         INIT_FUN_SET1:
         begin
             lcd_data <= 'h30;    //功能设定
             state <= INIT_FUN_SET2;
         end 

         INIT_FUN_SET2:
         begin
             lcd_data <= 'h30;    //功能设定
             state <= INIT_DISPLAY;
         end

         INIT_DISPLAY:
         begin
             lcd_data <= 'h0c;    //显示设定
             state <= INIT_CLEAR;
         end

         INIT_CLEAR:
         begin
             lcd_data <= 'h01;    //清屏
             state <= INIT_DOT_SET;
         end

         INIT_DOT_SET:
         begin
             lcd_data <= 'h06;    //进入点设定
             state <= SET_DDRAM;
         end

         SET_DDRAM:
         begin
             lcd_data <= 'h94;//2 line
             state <= WRITE_DATA1;
         end

         WRITE_DATA1:
         begin
             lcd_data <= data_buf;
             state <= SET_DDRAM;  //一直在同一个地方刷新显示
         end

 /*        STOP:
         begin
             en <= 1'b0;//显示完了，lcd_e就一直拉为低
             state <= STOP;
         end   */

         default: state <= IDLE;
     endcase

 /***************************************************/
 assign lcd_rw = 'b0;//只有写模式
 assign lcd_psb = 'b1;//并口模式
 assign lcd_en = en ?  lcd_clk : 'b0;
 /***************************************************/
 endmodule

ps2_top.v

 module ps2_top(
                 //input
                 sys_clk,
                 rst_n,
                 key_clk,
                 key_data,

                 //output
                 lcd_rs,
                 lcd_rw,
                 lcd_en,
                 lcd_data,
                 lcd_psb
                );
 input sys_clk;// 50MHZ
 input rst_n;
 input key_clk;      //键盘时钟
 input key_data;   //键盘数据

 output lcd_rs;//H:data    L:command
 output lcd_rw;//H:read module    L:write module
 output lcd_en;//H active
 output [:] lcd_data;
 output lcd_psb;//H:parallel    module    L:SPI module

 wire [:] data_buf;

 ps2_control   u1(
                     //input
                     .sys_clk(sys_clk),
                     .rst_n(rst_n),
                     .key_clk(key_clk),
                     .key_data(key_data),

                     //output
                     .data_buf(data_buf),
                    );

 LCD12864    u2(
                     //input
                     .sys_clk(sys_clk),
                     .rst_n(rst_n),
                     .data_buf(data_buf),

                     //output
                     .lcd_rs(lcd_rs),
                     .lcd_rw(lcd_rw),
                     .lcd_en(lcd_en),
                     .lcd_data(lcd_data),
                     .lcd_psb(lcd_psb)
                 );
 endmodule

PS2接口和LCD12864采用的是飞线连接的，显示效果图：