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(15)CT137A- 按键消抖设计

article 2024/12/24 7:12:58

（1）设计定义：设计一个按键消抖模块，实现消除按键机械抖动的影响，并实现以下功能：

按下S1，LED1、LED8点亮，否则熄灭
按下S2，LED2、LED7点亮，否则熄灭
按下S3，LED3、LED6点亮，否则熄灭
按下S4，LED4、LED5点亮，否则熄灭

（2）代码设计：

1.首先是20ms的计数器，一般来说，机械抖动的时间不会超过20ms。

2.状态机的定义和设计

//状态机定义
always@(posedge clk or negedge reset_n)		
	if(!reset_n)begin
		state <= IDLE;
		en_cnt <= 1'd0;
	end
	else begin
		case(state)
			IDLE:begin
				if(key_in == 1'd0)begin
					state <= PRESS;
					en_cnt <= 1'd1;
				end
				else begin
					state <= state;
					en_cnt <= 1'd0;
				end			
			end
			PRESS:begin
				if(cnt == MCNT - 20'd1 && key_in == 1'd0)begin
					state <= DOWN;
					en_cnt <= 1'd0;
				end
				else if(key_in == 1'd1)begin
					state <= IDLE;
					en_cnt <= 1'd0;
				end
				else begin
					state <= state;
					en_cnt <= en_cnt;
				end
			end
			DOWN:begin
				if(key_in == 1'd1)begin
					state <= REPRESS;
					en_cnt <= 1'd1;
				end
				else begin
					state <= state;
					en_cnt <= 1'd0;
				end
			end
			REPRESS:begin
				if(cnt == MCNT - 20'd1 && key_in == 1'd1)begin
					state <= IDLE;
					en_cnt <= 1'd0;
				end
				else if(key_in == 1'd0)begin
					state <= DOWN;
					en_cnt <= 1'd0;
				end
				else begin
					state <= state;
					en_cnt <= en_cnt;
				end
			end
			default:begin
				state <=	IDLE;
				en_cnt <= 1'd0;
			end
		endcase
	end

附上顶层文件：

module key_filter_top
(
	input		wire				clk 		,
	input		wire				reset_n	,
	input		wire	[3:0]		key_in	,  //{S4,S3,S2,S1}
	
	output	wire	[7:0]		LED	
);

key_filter		key_filter_inst0
(
	.clk			(clk		),
	.reset_n		(reset_n	),
	.key_in		(key_in[0]),
	
	.key_out		(),
	.LED1			(LED[0]),
	.LED2			(LED[7])
);

key_filter		key_filter_inst1
(
	.clk			(clk		),
	.reset_n		(reset_n	),
	.key_in		(key_in[1]),
	
	.key_out		(),
	.LED1			(LED[1]),
	.LED2			(LED[6])
);

key_filter		key_filter_inst2
(
	.clk			(clk		),
	.reset_n		(reset_n	),
	.key_in		(key_in[2]),
	
	.key_out		(),
	.LED1			(LED[2]),
	.LED2			(LED[5])
);

key_filter		key_filter_inst3
(
	.clk			(clk		),
	.reset_n		(reset_n	),
	.key_in		(key_in[3]),
	
	.key_out		(),
	.LED1			(LED[3]),
	.LED2			(LED[4])
);

endmodule

（3）实验现象：