实验现象：
按键每按下一次，三色LED切换一次状态。
核心源代码：
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
源代码下载链接：
链接：http://pan.baidu.com/s/1kVkOCgJ 密码：u1gd
iCore4链接：
