【iCore4 雙核心板_FPGA】例程二：GPIO輸入實驗——識別按鍵輸入

實驗現象：

按鍵每按下一次，三色LED切換一次狀態。

核心原始碼：

module key_ctrl(
    input clk_25m,
    input rst_n,
    input key,
    output fpga_ledr,
    output fpga_ledg,
    output fpga_ledb
);
//--------------------key_in--------------------------------//
parameter ms_10 = 250000;
reg key_r;
reg [17:0]low_cnt;
reg [17:0]hig_cnt;

always @(posedge clk_25m or negedge rst_n)    //按鍵消抖動，提取按鍵狀態
    if (!rst_n)
        begin
            key_r <= 1'd0;
            low_cnt <= 18'd0;
            hig_cnt <= 18'd0;
        end
    else if(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_r <= 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_r <= key;
                    low_cnt <= low_cnt;
                end
            else low_cnt <= low_cnt + 1'd1;
        end
        
wire key_state = key_r;
//--------------------led_ctrl-----------------------------//
reg [1:0]led_cnt;
reg ledr,ledg,ledb;

always@(negedge key_state or negedge rst_n)    //按鍵下降沿控制led狀態切換
    if (!rst_n)
        begin
            led_cnt <= 2'd0;
        end
    else if (led_cnt == 2'd2)
        begin
            led_cnt <= 2'd0;
        end
    else led_cnt <= led_cnt + 1'd1;

always@(posedge clk_25m or negedge rst_n)        //led狀態切換的狀態機
    if (!rst_n)
        begin
            ledr <= 1'd1;
            ledg <= 1'd1;
            ledb <= 1'd1;
        end
    else case(led_cnt)
            2'd0:                                            //紅燈亮
                begin
                    ledr <= 1'd0;
                    ledg <= 1'd1;
                    ledb <= 1'd1;
                end
            2'd1:                                            //綠燈亮
                begin
                    ledr <= 1'd1;
                    ledg <= 1'd0;
                    ledb <= 1'd1;
                end
            2'd2:                                            //藍燈亮
                begin
                    ledr <= 1'd1;
                    ledg <= 1'd1;
                    ledb <= 1'd0;
                end
                default:                                    //都不亮
                begin
                    ledr <= 1'd1;
                    ledg <= 1'd1;
                    ledb <= 1'd1;
                end
        endcase    
        
assign {fpga_ledr,fpga_ledg,fpga_ledb} = {ledr,ledg,ledb};

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

原始碼下載連結：

連結：http://pan.baidu.com/s/1kVkOCgJ 密碼：u1gd

iCore4連結：