iic协议verilog代码

以下是一个简单的I2C主机控制器的Verilog代码，用于在FPGA上实现I2C协议：

module i2c_master(
    input clk,
    input rst,
    input sda_i,
    output sda_o,
    inout scl_io
);

parameter IDLE = 2'b00;
parameter START = 2'b01;
parameter WRITE = 2'b10;
parameter READ = 2'b11;

reg [7:0] data_reg;
reg [6:0] addr_reg;
reg [1:0] state_reg;
reg [2:0] bit_cnt_reg;
reg [2:0] byte_cnt_reg;
reg [2:0] ack_cnt_reg;
reg [2:0] stop_cnt_reg;
reg [2:0] start_cnt_reg;

assign sda_o = (state_reg == WRITE) ? data_reg[bit_cnt_reg] : 1'bz;

always @(posedge clk) begin
    if (rst) begin
        state_reg <= IDLE;
        bit_cnt_reg <= 0;
        byte_cnt_reg <= 0;
        ack_cnt_reg <= 0;
        stop_cnt_reg <= 0;
        start_cnt_reg <= 0;
    end else begin
        case (state_reg)
            IDLE: begin
                if (!sda_i && !scl_io) begin
                    state_reg <= START;
                    start_cnt_reg <= 1;
                end
            end
            START: begin
                if (start_cnt_reg == 1) begin
                    sda_o <= 0;
                    start_cnt_reg <= 2;
                end else if (start_cnt_reg == 2) begin
                    scl_io <= 0;
                    start_cnt_reg <= 3;
                end else if (start_cnt_reg == 3) begin
                    sda_o <= 1;
                    start_cnt_reg <= 4;
                end else if (start_cnt_reg == 4) begin
                    scl_io <= 1;
                    state_reg <= WRITE;
                    bit_cnt_reg <= 0;
                    byte_cnt_reg <= 0;
                    ack_cnt_reg <= 0;
                end
            end
            WRITE: begin
                if (ack_cnt_reg == 0) begin
                    if (bit_cnt_reg == 7) begin
                        ack_cnt_reg <= 1;
                        bit_cnt_reg <= 0;
                        byte_cnt_reg <= byte_cnt_reg + 1;
                        if (byte_cnt_reg == 2) begin
                            state_reg <= STOP;
                            stop_cnt_reg <= 1;
                        end else begin
                            state_reg <= WRITE;
                        end
                    end else begin
                        bit_cnt_reg <= bit_cnt_reg + 1;
                    end
                end else if (ack_cnt_reg == 1) begin
                    if (sda_i) begin
                        state_reg <= IDLE;
                    end else begin
                        ack_cnt_reg <= 2;
                    end
                end else if (ack_cnt_reg == 2) begin
                    ack_cnt_reg <= 0;
                    state_reg <= WRITE;
                end
            end
            READ: begin
                // TODO: implement read state
            end
            STOP: begin
                if (stop_cnt_reg == 1) begin
                    sda_o <= 0;
                    stop_cnt_reg <= 2;
                end else if (stop_cnt_reg == 2) begin
                    scl_io <= 0;
                    stop_cnt_reg <= 3;
                end else if (stop_cnt_reg == 3) begin
                    sda_o <= 1;
                    stop_cnt_reg <= 4;
                end else if (stop_cnt_reg == 4) begin
                    scl_io <= 1;
                    state_reg <= IDLE;
                end
            end
        endcase
    end
end

endmodule