verilog期末编程题

### Verilog期末编程题目及练习 #### 题目1：设计一个四位二进制计数器 该模块应具有同步清零功能和使能控制。当`rst_n`为低电平时，计数值重置为0；当`en`为高电平且`clk`上升沿到来时，计数值加1。 ```verilog module counter_4bit ( input clk, input rst_n, input en, output reg [3:0] q ); always @(posedge clk or negedge rst_n) begin if (!rst_n) q <= 4'b0; else if (en) q <= q + 1; end endmodule ``` 此代码展示了如何创建一个简单的四位二进制计数器[^1]。 #### 题目2：构建带有异步复位的8位全加法器 要求能够处理两个8位输入以及来自低位的进位输入，并提供结果输出与向高位传递的新进位信号。 ```verilog module adder_8bit_async_reset( input wire clk, input wire rst_n, input wire cin, input wire [7:0] a, input wire [7:0] b, output reg [7:0] sum, output reg cout ); // 异步复位逻辑 always_ff @(posedge clk, negedge rst_n) begin : proc_sum_cout if (~rst_n) begin sum <= 'b0; cout <= 1'b0; end else begin {cout,sum} = a + b + cin; end end endmodule ``` 上述代码实现了带异步复位特性的八位全加法器的设计[^3]。 #### 题目3：实现状态机来控制LED灯闪烁模式 通过有限状态机(FSM)，根据不同的按键输入改变LED灯的状态（熄灭、常亮、慢闪、快闪）。每种状态下保持一定时间后再切换到下一个状态。 ```verilog module led_fsm( input wire clk, input wire btn, output reg led_on ); typedef enum logic [1:0] { OFF = 2'd0, ON = 2'd1, SLOW_BLINK = 2'd2, FAST_BLINK = 2'd3 } state_t; state_t current_state, next_state; parameter CLK_FREQ_HZ = 50_000_000; // 假设系统频率为50MHz localparam TIME_SLOW_MS = 500; localparam TIME_FAST_MS = 100; reg [$clog2(CLK_FREQ_HZ * TIME_SLOW_MS / 1000)-1:0] slow_counter; reg [$clog2(CLK_FREQ_HZ * TIME_FAST_MS / 1000)-1:0] fast_counter; always_ff @(posedge clk) begin case(current_state) OFF: led_on <= 1'b0; ON: led_on <= 1'b1; SLOW_BLINK: begin if(slow_counter >= $unsigned((CLK_FREQ_HZ * TIME_SLOW_MS)/1000)) begin slow_counter <= 0; led_on <= ~led_on; end else begin slow_counter <= slow_counter + 1; end end FAST_BLINK: begin if(fast_counter >= $unsigned((CLK_FREQ_HZ * TIME_FAST_MS)/1000)) begin fast_counter <= 0; led_on <= ~led_on; end else begin fast_counter <= fast_counter + 1; end end endcase if(btn) begin unique case(current_state) OFF: next_state <= ON; ON: next_state <= SLOW_BLINK; SLOW_BLINK:next_state <= FAST_BLINK; FAST_BLINK:next_state <= OFF; endcase end else begin next_state <= current_state; end current_state <= next_state; end endmodule ``` 这段程序定义了一个用于控制LED灯光效果的状态机结构[^2]。