用verilog写一个I2C的master

好的，以下是一个简单的Verilog代码实现I2C Master：

module i2c_master (
    input clk,
    input rst,
    output sda,
    output scl,
    input [7:0] slave_addr,
    input [7:0] data_in,
    input write,
    output reg ack,
    output reg data_out,
    output reg done
);

parameter IDLE = 2'b00, START = 2'b01, ADDR = 2'b10, DATA = 2'b11;

reg [1:0] state;
reg [7:0] cnt;
reg [7:0] reg_slave_addr;
reg [7:0] reg_data;
reg [3:0] bit_cnt;
reg [3:0] reg_bit_cnt;
reg [7:0] reg_bit_data;
reg [7:0] shift_reg;
wire [7:0] shift_data;

assign shift_data = shift_reg;

assign sda = (state == START || state == ADDR || state == DATA) ? shift_data[7] : 1'b1;
assign scl = (state == START || state == ADDR || state == DATA) ? 1'b0 : 1'b1;

always @(posedge clk) begin
    if (rst) begin
        state <= IDLE;
        cnt <= 0;
        reg_slave_addr <= 0;
        reg_data <= 0;
        ack <= 1'b0;
        data_out <= 1'b0;
        done <= 1'b0;
        bit_cnt <= 0;
        reg_bit_cnt <= 0;
        reg_bit_data <= 0;
        shift_reg <= 0;
    end else begin
        case (state)
            IDLE: begin
                reg_slave_addr <= slave_addr;
                reg_data <= data_in;
                if (write) begin
                    state <= START;
                    cnt <= 0;
                end else begin
                    state <= START;
                    cnt <= 1;
                end
            end
            START: begin
                shift_reg <= { 1'b0, 1'b0, 1'b1, reg_slave_addr[6:0], write };
                state <= ADDR;
                bit_cnt <= 0;
            end
            ADDR: begin
                bit_cnt <= bit_cnt + 1;
                if (bit_cnt == 8) begin
                    ack <= ~sda;
                    if (ack) begin
                        state <= DATA;
                        cnt <= 0;
                    end else begin
                        state <= IDLE;
                        done <= 1'b1;
                    end
                    bit_cnt <= 0;
                end else begin
                    reg_bit_data <= sda;
                    reg_bit_cnt <= bit_cnt;
                    state <= ADDR;
                end
            end
            DATA: begin
                if (write) begin
                    shift_reg <= { 1'b0, 1'b0, 1'b0, reg_data[7:0] };
                    state <= DATA;
                    bit_cnt <= bit_cnt + 1;
                    if (bit_cnt == 8) begin
                        ack <= ~sda;
                        if (ack) begin
                            state <= START;
                            cnt <= cnt + 1;
                            if (cnt == 2) begin
                                state <= IDLE;
                                done <= 1'b1;
                            end
                        end else begin
                            state <= IDLE;
                            done <= 1'b1;
                        end
                        bit_cnt <= 0;
                    end
                end else begin
                    if (cnt == 0) begin
                        shift_reg <= { 1'b0, 1'b0, 1'b1, reg_slave_addr[6:0], write };
                        state <= ADDR;
                        bit_cnt <= 0;
                    end else begin
                        shift_reg <= { 1'b0, 1'b1, 1'b0, 8'b0 };
                        state <= DATA;
                        bit_cnt <= bit_cnt + 1;
                        if (bit_cnt == 8) begin
                            ack <= ~sda;
                            data_out <= shift_data[7];
                            state <= DATA;
                            cnt <= cnt - 1;
                            bit_cnt <= 0;
                            if (cnt == 0) begin
                                state <= IDLE;
                                done <= 1'b1;
                            end
                        end
                    end
                end
            end
        endcase
    end
end

endmodule

该代码实现了一个I2C Master，包括发送和接收数据的功能。在使用时，需要提供时钟信号、复位信号、从设备地址、要发送或接收的数据、以及写入或读取标志位。输出包括SDA和SCL信号、应答信号、发送或接收的数据、以及完成标志位。