写出iic的Verilog代码

以下是一个简单的I2C总线控制器的Verilog代码：

module iic_controller(
    input clk,
    input rst_n,
    input sda,
    input scl,
    output reg sda_out,
    output reg sda_ack
);

// 定义I2C状态机的状态
localparam IDLE = 0, START = 1, WRITE = 2, READ = 3, STOP = 4;

// 定义I2C状态机的变量
reg [7:0] data_in;
reg [7:0] data_out;
reg [2:0] state_reg;
reg [2:0] state_next;
reg sda_dir;

// 初始化I2C状态机
always @(posedge clk or negedge rst_n) begin
    if (!rst_n) begin
        state_reg <= IDLE;
        data_in <= 8'h00;
        sda_out <= 1'b1;
        sda_ack <= 1'b1;
        sda_dir <= 1'b1;
    end else begin
        state_reg <= state_next;
        data_in <= {data_in[6:0], sda};
    end
end

// 定义I2C状态机的状态转换和输出逻辑
always @(*) begin
    state_next = state_reg;
    case (state_reg)
        IDLE: begin
            if (~sda & scl) begin
                state_next = START;
            end
        end
        START: begin
            sda_out = 1'b0;
            sda_dir = 1'b0;
            if (scl) begin
                state_next = WRITE;
            end
        end
        WRITE: begin
            sda_out = data_out[7];
            sda_dir = 1'b0;
            if (scl) begin
                data_out <= {data_out[6:0], 1'b0};
                if (data_out == 8'h00) begin
                    state_next = READ;
                end
            end
        end
        READ: begin
            sda_out = 1'b1;
            sda_dir = 1'b1;
            if (scl) begin
                if (data_in[7]) begin
                    sda_ack = 1'b0;
                    data_in <= {data_in[6:0], 1'b0};
                end else begin
                    sda_ack = 1'b1;
                    state_next = STOP;
                end
            end
        end
        STOP: begin
            sda_out = 1'b1;
            sda_dir = 1'b0;
            if (scl) begin
                state_next = IDLE;
            end
        end
        default: begin
            state_next = IDLE;
        end
    endcase
end

// 设置SDA引脚的输入/输出方向
assign sda = (sda_dir) ? 1'bz : sda_out;

endmodule

这个I2C总线控制器实现了简单的主机模式，可以发送和接收8位数据。可以将其与外部I2C设备连接，并通过修改 `data_out` 和 `data_in` 来控制发送和接收的数据。