时尚网站设计案例色盲悖论
一、设计目标
在DE2-115板子上用 Verilog编程实现一个分秒计数器,并具备按键暂停、按键消抖功能。
(1)引脚分配符合DE2-115开发板规范;
(2)基于状态机思想设计,20ms周期消除机械抖动。
二、程序设计实现代码
1、顶层模块
module top(input CLOCK_50, // 50MHz时钟(PIN_Y2)input KEY0, // 复位按钮(PIN_M23)input KEY1, // 暂停按钮(PIN_M21)output [6:0] HEX0, // 秒个位(PIN_G18等)output [6:0] HEX1, // 秒十位(PIN_M24等)output [6:0] HEX2, // 分个位(PIN_K22等)output [6:0] HEX3 // 分十位(PIN_K21等)
);// 状态定义
localparam RUN = 1'b0;
localparam PAUSE = 1'b1;// 内部信号声明
wire reset = ~KEY0; // 低电平有效复位
wire clk_1hz; // 1Hz时钟
wire carry_sec;
wire key_stable; // 消抖后的按键信号
reg key_stable_d; // 用于边沿检测的延迟寄存器// 计数器输出信号定义
wire [3:0] sec_ones;
wire [3:0] sec_tens;
wire [3:0] min_ones;
wire [3:0] min_tens;// 状态寄存器
reg current_state;
reg next_state;// 消抖后的暂停信号
debounce pause_debouncer(.clk(CLOCK_50),.button(~KEY1), // KEY1低电平有效.out(key_stable)
);// 边沿检测逻辑(上升沿)
always @(posedge CLOCK_50) beginkey_stable_d <= key_stable;
end
wire key_rise = key_stable & ~key_stable_d;// 状态转移逻辑
always @(*) begincase (current_state)RUN: next_state = key_rise ? PAUSE : RUN;PAUSE: next_state = key_rise ? RUN : PAUSE;default: next_state = RUN;endcase
end// 状态翻转逻辑(每次按键翻转pause_state)
always @(posedge CLOCK_50 or posedge reset) beginif (reset) current_state <= RUN;else current_state <= next_state;
end
// 输出控制信号
wire pause = (current_state == PAUSE);// 时钟分频模块实例化
clk_divider clk_div(.clk(CLOCK_50),.reset(reset),.pause(pause),.clk_1hz(clk_1hz)
);// 秒计数器模块实例化
second_counter sec_cnt(.clk(clk_1hz),.reset(reset),.enable(~pause), // 暂停时停止计数.sec_ones(sec_ones),.sec_tens(sec_tens),.carry_sec(carry_sec)
);// 分钟计数器模块实例化
minute_counter min_cnt(.clk(clk_1hz),.reset(reset),.inc(carry_sec),.min_ones(min_ones),.min_tens(min_tens)
);// 七段译码器实例化
seg7_decoder seg_sec0(.bcd(sec_ones), .seg(HEX0)); // 秒个位
seg7_decoder seg_sec1(.bcd(sec_tens), .seg(HEX1)); // 秒十位
seg7_decoder seg_min0(.bcd(min_ones), .seg(HEX2)); // 分个位
seg7_decoder seg_min1(.bcd(min_tens), .seg(HEX3)); // 分十位endmodule
2、时钟分频模块(带暂停控制)
// 时钟分频模块(带暂停控制)
module clk_divider(input clk,input reset,input pause, output reg clk_1hz
);
reg [25:0] counter;always @(posedge clk or posedge reset) beginif (reset) begincounter <= 0;clk_1hz <= 0;endelse if (!pause) begin // 暂停时停止分频if (counter == 26'd24_999_999) begincounter <= 0;clk_1hz <= ~clk_1hz;endelse begincounter <= counter + 1;endend
end
endmodule
3、带使能端的秒计数器
// 带使能端的秒计数器
module second_counter(input clk,input reset,input enable, // 使能信号output reg [3:0] sec_ones,output reg [3:0] sec_tens,output carry_sec // 改为组合逻辑输出
);
// 组合逻辑判断是否到达59秒
assign carry_sec = (sec_ones == 9) && (sec_tens == 5);
always @(posedge clk or posedge reset) beginif (reset) beginsec_ones <= 0;sec_tens <= 0;endelse if (enable) beginif (sec_ones == 9) beginsec_ones <= 0;if (sec_tens == 5)sec_tens <= 0;elsesec_tens <= sec_tens + 1;endelse beginsec_ones <= sec_ones + 1;endend
end
endmodule
4、分钟计数器
// 分钟计数器
module minute_counter(input clk,input reset,input inc,output reg [3:0] min_ones,output reg [3:0] min_tens
);
always @(posedge clk or posedge reset) beginif (reset) beginmin_ones <= 0;min_tens <= 0;endelse if (inc) beginif (min_ones == 9) beginmin_ones <= 0;if (min_tens == 5)min_tens <= 0;elsemin_tens <= min_tens + 1;endelse beginmin_ones <= min_ones + 1;endend
end
endmodule
5、七段译码器
// 七段译码器
module seg7_decoder(input [3:0] bcd,output reg [6:0] seg
);
always @(*) begincase (bcd)4'd0 : seg = 7'b1000000; // 04'd1 : seg = 7'b1111001; // 14'd2 : seg = 7'b0100100; // 24'd3 : seg = 7'b0110000; // 34'd4 : seg = 7'b0011001; // 44'd5 : seg = 7'b0010010; // 54'd6 : seg = 7'b0000010; // 64'd7 : seg = 7'b1111000; // 74'd8 : seg = 7'b0000000; // 84'd9 : seg = 7'b0010000; // 9default : seg = 7'b1111111; // 灭endcase
end
endmodule
6、按键消抖模块(20ms)
// 按键消抖模块(20ms消抖)
module debounce(input clk,input button,output reg out
);
reg [19:0] counter;
reg [2:0] button_sync; // 三级同步器
always @(posedge clk) begin// 同步器链button_sync <= {button_sync[1:0], button};// 消抖逻辑if (button_sync[2] != out) begincounter <= counter + 1;if (&counter) begin // 计满20ms(50MHz时钟)out <= button_sync[2];counter <= 0;endendelse begincounter <= 0;end
end
endmodule
三、结果演示
四、总结
状态机设计有效提升了系统的可靠性和可维护性,按键消抖是嵌入式系统设计的必备技能,同时时序分析在FPGA设计中至关重要。由于本人初步学习认知浅薄,上述内容或有诸多不详错漏之处,望各位海涵并指出批正。