【iCore4 双核心板_FPGA】例程二：GPIO输入实验——识别按键输入

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)    //按键消抖动，提取按键状态
if (!rst_n)
begin
key_r <= 1'd0;
low_cnt <= 18'd0;
hig_cnt <= 18'd0;
end
else if(key)                                    //检测按键状态为高时，延时10ms，把按键状态提取出来。
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                                                    //按键状态为低时，延时10ms，把按键状态提取出来。
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)    //按键下降沿控制led状态切换
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状态切换的状态机
if (!rst_n)
begin
ledr <= 1'd1;
ledg <= 1'd1;
ledb <= 1'd1;
end
else case(led_cnt)
2'd0:                                            //红灯亮
begin
ledr <= 1'd0;
ledg <= 1'd1;
ledb <= 1'd1;
end
2'd1:                                            //绿灯亮
begin
ledr <= 1'd1;
ledg <= 1'd0;
ledb <= 1'd1;
end
2'd2:                                            //蓝灯亮
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