【iCore1S 雙核心板_FPGA】例程六：狀態機實驗——狀態機使用

核心程式碼：

module FSM(  
    input CLK_12M,
    input FPGA_KEY,
    output FPGA_LEDR,
    output FPGA_LEDG,
    output FPGA_LEDB                 
);
//----------------------state--------------------//
    parameter state_RST  = 3'd0;         //燈熄滅
    parameter state_LEDR = 3'd1;         //紅燈亮
    parameter state_LEDG = 3'd2;         //綠燈亮
    parameter state_LEDB = 3'd3;          //藍燈亮
    parameter state_LED_R_G_B = 3'd4; //燈都亮（接近白光）
    
//----------------------rst_n--------------------//
    reg rst_n;
    reg [3:0]cnt_rst;
    
    always@(posedge CLK_12M)
        if(cnt_rst==4'd10)
            begin 
                cnt_rst <= 4'd10;
                rst_n = 1'd1;
            end
        else cnt_rst <= cnt_rst + 1'd1;
        
//-------------------key in---------------------//
    reg key;
    reg [17:0]low_cnt;
    reg [17:0]hig_cnt;
    parameter ms_10 =120000;
    
    always@(posedge CLK_12M or negedge rst_n)
        begin
            if(!rst_n)
                begin
                    key <= 1'd1;
                    low_cnt <= 18'd0;
                    hig_cnt <= 18'd0;
                end
             else if(FPGA_KEY)  //檢測按鍵狀態為高時，延時10ms，把按鍵狀態提取出來。
                begin
                    low_cnt <= 18'd0;
                    if(hig_cnt==ms_10)
                        begin
                            key <= FPGA_KEY;
                            hig_cnt <= hig_cnt;
                        end
                    else hig_cnt <= hig_cnt + 1'd1;
                end
            else         ////按鍵狀態為低時，延時10ms，把按鍵狀態提取出來。
                begin 
                    hig_cnt <= 18'd0;
                    if(low_cnt==ms_10)
                        begin
                            key <= FPGA_KEY;
                            low_cnt <= low_cnt;
                        end
                    else low_cnt <= low_cnt +1'd1;
                end 
        end
    
//----------------led_state------------------//
    reg [2:0]led_state;
        
    //key的下降沿，即按鍵按下後，進行狀態轉換
    always@(negedge key or negedge rst_n)
        begin
            if(!rst_n)
                begin
                    led_state <= 3'd0;
                end
            else 
                begin
                    led_state <= led_state + 1'd1;
                    if (led_state == 3'd4)
                        begin
                            led_state <= 3'd0;
                        end                                            
                end            
        end
        
//------------------led---------------------//    
    reg ledr,ledg,ledb;
    
    always@(posedge CLK_12M or negedge rst_n)
        begin 
            if(!rst_n)
                begin 
                    ledr <= 1'd1;
                    ledg <= 1'd1;
                    ledb <= 1'd1;
                end
        else    case(led_state)
                    state_RST:            //燈熄滅
                        begin
                            ledr <= 1'd1;
                            ledg <= 1'd1;
                            ledb <= 1'd1;
                        end
                    state_LEDR:         //紅燈亮
                        begin
                            ledr <= 1'd0;
                            ledg <= 1'd1;
                            ledb <= 1'd1;
                        end                     
                    state_LEDG:            //綠燈亮
                        begin
                            ledr <= 1'd1;
                            ledg <= 1'd0;
                            ledb <= 1'd1;
                        end 
                    state_LEDB:            //藍燈亮
                        begin
                            ledr <= 1'd1;
                            ledg <= 1'd1;
                            ledb <= 1'd0;
                        end 
                    state_LED_R_G_B:    //燈交替亮
                        begin
                            
                            ledr <= 1'd0;
                            ledg <= 1'd0;
                            ledb <= 1'd0;
                        end
                    default:                //都不亮
                        begin
                        ledr <= 1'd1;
                      ledg <= 1'd1;
                      ledb <= 1'd1;
                        end
                endcase
        end
                        
    assign FPGA_LEDR = ledr;
    assign FPGA_LEDG = ledg;
    assign FPGA_LEDB = ledb;

//-----------------endmodule-----------------//        
endmodule 

實驗方法及指導書:

連結：http://pan.baidu.com/s/1o8skJCe 密碼：var9