用verilog写出一个可以生成 4 种基础波形（方波、正弦波、锯齿波、三角波），可以按键控制调频和使用按键控制波形切换的代码和测试代码

下面是一个用 Verilog 实现的基础波形生成器，其中可以生成方波、正弦波、锯齿波和三角波。同时，可以使用按键来调整频率和切换波形。请注意，本代码仅为示例，您需要根据自己的实际需求进行修改和优化。

module waveform_generator(
    input clk,        // 时钟信号
    input rst,        // 复位信号
    input [1:0] freq_control,   // 频率控制信号
    input [1:0] waveform_select,   // 波形选择信号
    output reg wave_out      // 生成的波形信号
);

// 定义计数器的位数
parameter COUNTER_WIDTH = 16;

// 定义常量
parameter PI = 3.1415926;

// 定义计数器和计数器的最大值
reg [COUNTER_WIDTH-1:0] counter = 0;
parameter COUNTER_MAX = 2 ** COUNTER_WIDTH;

// 定义频率控制值对应的计数器增量值
parameter [1:0] FREQ_CONTROL_INCREMENT [0:3] = '{2'b01, 2'b10, 2'b11, 2'b00};

// 定义正弦波的 LUT
parameter [7:0] SINE_LUT [0:255] = '{128,131,134,137,140,143,146,149,151,154,157,160,163,165,168,171,174,176,179,181,184,186,189,191,193,196,198,200,202,204,206,208,210,212,213,215,217,218,220,221,223,224,225,227,228,229,230,231,232,233,234,235,236,236,237,238,238,239,239,240,240,240,240,240,240,240,240,240,240,239,239,238,238,237,236,236,235,234,233,232,231,230,229,228,227,225,224,223,221,220,218,217,215,213,212,210,208,206,204,202,200,198,196,193,191,189,186,184,181,179,176,174,171,168,165,163,160,157,154,151,149,146,143,140,137,134,131,128,125,122,119,116,113,110,107,105,102,99,96,93,91,88,85,82,80,77,75,72,70,67,65,62,60,58,56,54,52,50,48,46,44,42,40,38,36,35,33,32,30,29,27,26,25,23,22,21,20,19,18,17,16,15,15,14,13,13,12,12,11,11,11,11,11,11,11,11,11,11,12,12,13,13,14,15,15,16,17,18,19,20,21,22,23,25,26,27,29,30,32,33,35,36,38,40,42,44,46,48,50,52,54,56,58,60,62,65,67,70,72,75,77,80,82,85,88,91,93,96,99,102,105,107,110,113,116,119,122,125};

// 定义锯齿波的 LUT
parameter [7:0] SAWTOOTH_LUT [0:255] = '{0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72,73,74,75,76,77,78,79,80,81,82,83,84,85,86,87,88,89,90,91,92,93,94,95,96,97,98,99,100,101,102,103,104,105,106,107,108,109,110,111,112,113,114,115,116,117,118,119,120,121,122,123,124,125,126,127,128,129,130,131,132,133,134,135,136,137,138,139,140,141,142,143,144,145,146,147,148,149,150,151,152,153,154,155,156,157,158,159,160,161,162,163,164,165,166,167,168,169,170,171,172,173,174,175,176,177,178,179,180,181,182,183,184,185,186,187,188,189,190,191,192,193,194,195,196,197,198,199,200,201,202,203,204,205,206,207,208,209,210,211,212,213,214,215,216,217,218,219,220,221,222,223,224,225,226,227,228,229,230,231,232,233,234,235,236,237,238,239,240,241,242,243,244,245,246,247,248,249,250,251,252,253,254,255};

always @(posedge clk or posedge rst) begin
    if(rst) begin
        counter <= 0;
    end else begin
        // 根据频率控制信号更新计数器
        counter <= counter + FREQ_CONTROL_INCREMENT[freq_control];
    end
end

always @(*) begin
    case(waveform_select)
        2'b00: wave_out = counter[COUNTER_WIDTH-1];   // 方波
        2'b01: wave_out = SINE_LUT[counter[COUNTER_WIDTH-1:8]];   // 正弦波
        2'b10: wave_out = SAWTOOTH_LUT[counter[COUNTER_WIDTH-1:8]];   // 锯齿波
        2'b11: wave_out = (counter[COUNTER_WIDTH-2:8] << 1) - COUNTER_MAX;   // 三角波
    endcase
end

endmodule

下面是一个测试代码，可以使用按键控制频率和波形选择。请注意，这里使用的是 Basys3 开发板，如果您使用的是其他开发板，需要根据实际情况修改 IO 管脚和按键信号。

module waveform_generator_tb;

// 定义时钟周期
parameter PERIOD = 10;

// 定义按键信号
reg [1:0] freq_control = 2'b00;
reg [1:0] waveform_select = 2'b00;

// 定义测试模块的实例
waveform_generator dut(
    .clk(clk),
    .rst(rst),
    .freq_control(freq_control),
    .waveform_select(waveform_select),
    .wave_out(wave_out)
);

// 定义时钟信号
reg clk = 0;
always #(PERIOD/2) clk = ~clk;

// 定义复位信号
reg rst = 0;
initial begin
    rst = 1;
    #(PERIOD*10) rst = 0;
end

// 定义波形输出信号
wire wave_out;

// 定义按键信号
wire [3:0] btn = {1'b0, btn_center, btn_up, btn_down};

// 定义按键模块的实例
btn_controller btn_controller_inst(
    .clk(clk),
    .btn(btn)
);

// 定义按键控制逻辑
always @(posedge clk) begin
    if(btn_up && freq_control < 2'b11) begin
        freq_control <= freq_control + 1;
    end
    if(btn_down && freq_control > 2'b00) begin
        freq_control <= freq_control - 1;
    end
    if(btn_center) begin
        waveform_select <= waveform_select + 1;
        if(waveform_select > 2'b11) begin
            waveform_select <= 2'b00;
        end
    end
end

// 定义波形输出逻辑
always @(posedge clk) begin
    $display("Waveform: %s, Frequency: %d", waveform_select, freq_control);
    $display("Waveform Value: %d", wave_out);
end

endmodule

以上代码仅供参考，您需要根据自己的实际需求进行修改和优化。