写一段I2C的verilog代码

以下是一个简单的I2C主机控制器的Verilog代码，用于读取从设备中的数据：

module i2c_master(
    input clk,
    input reset,
    output reg sda,
    output reg scl,
    input [7:0] address,
    output reg [7:0] data_out,
    input data_in_ack,
    input data_in,
    input data_out_ack,
    input data_out_req,
    output reg done
);

// I2C states
localparam IDLE = 2'b00;
localparam START = 2'b01;
localparam WRITE = 2'b10;
localparam READ = 2'b11;

reg [7:0] data_in_reg;
reg [7:0] data_out_reg;
reg [7:0] address_reg;
reg [1:0] state;

// Initialize state machine
always @(posedge clk) begin
    if (reset) begin
        state <= IDLE;
        sda <= 1;
        scl <= 1;
        data_out <= 8'h00;
        done <= 0;
    end else begin
        case (state)
            IDLE: begin
                state <= START;
                scl <= 1;
                sda <= 1;
            end
            START: begin
                state <= WRITE;
                scl <= 0;
                sda <= 0;
            end
            WRITE: begin
                if (data_out_req) begin
                    data_out_reg <= data_out;
                end
                if (data_out_ack) begin
                    data_out_reg <= data_out_reg >> 1;
                end
                if (data_out_ack && address_reg[0]) begin
                    state <= READ;
                    sda <= 1;
                end else if (data_out_ack) begin
                    address_reg <= address_reg >> 1;
                end
                scl <= 1;
                sda <= address_reg[0] || data_out_reg[0];
            end
            READ: begin
                if (data_in_ack) begin
                    data_in_reg <= data_in;
                end
                if (data_in_ack && address_reg[0]) begin
                    data_out_reg <= data_in_reg;
                    done <= 1;
                    sda <= 1;
                    state <= IDLE;
                end else if (data_in_ack) begin
                    address_reg <= address_reg >> 1;
                    sda <= 0;
                end
                scl <= 1;
            end
        endcase
    end
end

endmodule

此代码实现了一个简单的I2C主机控制器，能够读取从设备中的数据。它包含一个状态机，以及一些寄存器和逻辑用于控制I2C总线上的时序和数据流。要使用此代码，您需要添加一些额外的逻辑来处理I2C总线上的ACK，以及从设备的地址和数据。