Verilog 实现 I2C 转 MDIO 模块

以下是用 Verilog 编写的 I2C 转 MDIO 模块的示例代码：

module i2c_to_mdio (
  input wire clk,
  input wire rst,
  input wire i2c_scl,
  input wire i2c_sda,
  output wire mdio_clk,
  output wire mdio_data,
  output wire mdio_en
);

  reg [3:0] state;
  reg [7:0] i2c_data;
  reg [3:0] bit_counter;
  reg [7:0] mdio_data_reg;
  reg mdio_clk_reg;
  reg mdio_en_reg;

  wire i2c_sda_reg;

  assign i2c_sda_reg = i2c_sda;

  always @(posedge clk or posedge rst) begin
    if (rst) begin
      state <= 4'b0000;
      i2c_data <= 8'b00000000;
      bit_counter <= 4'b0000;
      mdio_data_reg <= 8'b00000000;
      mdio_clk_reg <= 1'b0;
      mdio_en_reg <= 1'b0;
    end else begin
      case (state)
        4'b0000: begin // Idle state
          if (!i2c_scl && i2c_sda_reg) begin
            state <= 4'b0001; // Start condition detected
          end
        end
        4'b0001: begin // Start condition detected
          if (i2c_scl && !i2c_sda_reg) begin
            state <= 4'b0010; // Addressing state
          end else if (!i2c_scl && !i2c_sda_reg) begin
            state <= 4'b0001; // Restart condition detected
          end else if (i2c_scl && i2c_sda_reg) begin
            state <= 4'b0000; // False start condition detected
          end
        end
        4'b0010: begin // Addressing state
          if (!i2c_scl && i2c_sda_reg) begin
            state <= 4'b0011; // Address acknowledged
          end
        end
        4'b0011: begin // Address acknowledged
          if (i2c_scl && !i2c_sda_reg) begin
            state <= 4'b0100; // Data state
          end else if (!i2c_scl && !i2c_sda_reg) begin
            state <= 4'b0011; // Restart condition detected
          end else if (i2c_scl && i2c_sda_reg) begin
            state <= 4'b0000; // False start condition detected
          end
        end
        4'b0100: begin // Data state
          if (!i2c_scl && i2c_sda_reg) begin
            state <= 4'b0101; // Data acknowledged
          end
        end
        4'b0101: begin // Data acknowledged
          if (i2c_scl && !i2c_sda_reg) begin
            state <= 4'b0100; // Data state
          end else if (!i2c_scl && !i2c_sda_reg) begin
            state <= 4'b0101; // Restart condition detected
          end else if (i2c_scl && i2c_sda_reg) begin
            state <= 4'b0000; // False start condition detected
          end
        end
      endcase
    end
  end

  always @(posedge clk) begin
    case (state)
      4'b0000: begin // Idle state
        i2c_data <= 8'b00000000;
        bit_counter <= 4'b0000;
        mdio_data_reg <= 8'b00000000;
        mdio_clk_reg <= 1'b0;
        mdio_en_reg <= 1'b0;
      end
      4'b0010: begin // Addressing state
        i2c_data <= 8'b00000000; // Address for MDIO
        bit_counter <= 4'b0000;
        mdio_data_reg <= 8'b00000000;
        mdio_clk_reg <= 1'b0;
        mdio_en_reg <= 1'b0;
      end
      4'b0100: begin // Data state
        if (bit_counter < 4'd7) begin
          i2c_data <= {i2c_data[6:0], i2c_sda_reg};
          bit_counter <= bit_counter + 1;
        end else begin
          i2c_data <= {i2c_data[6:0], i2c_sda_reg};
          bit_counter <= 4'b0000;
        end
        mdio_data_reg <= i2c_data;
        mdio_clk_reg <= 1'b0;
        mdio_en_reg <= 1'b0;
      end
    endcase
  end

  always @(posedge clk) begin
    mdio_clk <= mdio_clk_reg;
    mdio_data <= mdio_data_reg;
    mdio_en <= mdio_en_reg;
    if (state == 4'b0100 && bit_counter == 4'd7) begin
      mdio_clk_reg <= 1'b1;
      mdio_en_reg <= 1'b1;
    end else begin
      mdio_clk_reg <= 1'b0;
      mdio_en_reg <= 1'b0;
    end
  end

endmodule

该模块使用状态机来处理 I2C 通信过程，并通过适当的时钟和使能信号生成 MDIO 信号。