verilog 实现i2c slave详细代码

以下是一个简单的 Verilog 实现 I2C Slave 的代码示例：

module i2c_slave (
    input wire clk,
    input wire rst,
    input wire sda,
    input wire scl,
    output reg ack,
    output reg [7:0] data_out
);

reg [7:0] data_in;
reg [2:0] state;
reg [3:0] bit_counter;
reg [2:0] addr;
reg [7:0] reg_data [0:3];

parameter ADDR_REG_0 = 3'd0;
parameter ADDR_REG_1 = 3'd1;
parameter ADDR_REG_2 = 3'd2;
parameter ADDR_REG_3 = 3'd3;

// 初始化
initial begin
    state = 3'd0;
    bit_counter = 4'd0;
    addr = 3'd0;
    data_out = 8'h00;
    ack = 1'b1;
end

// 状态机
always @(posedge clk) begin
    if (rst) begin
        state <= 3'd0;
        bit_counter <= 4'd0;
        addr <= 3'd0;
        data_out <= 8'h00;
        ack <= 1'b1;
    end else begin
        case (state)
            3'd0: begin
                if (!sda && scl) begin
                    state <= 3'd1;
                    bit_counter <= 4'd0;
                    ack <= 1'b1;
                end
            end
            3'd1: begin
                if (sda && scl) begin
                    state <= 3'd2;
                    bit_counter <= 4'd0;
                    ack <= 1'b1;
                end else if (!sda && !scl) begin
                    state <= 3'd10;
                    bit_counter <= 4'd0;
                    ack <= 1'b1;
                end
            end
            3'd2: begin
                if (!sda && !scl) begin
                    state <= 3'd3;
                    bit_counter <= 4'd0;
                    ack <= 1'b1;
                end
            end
            3'd3: begin
                if (bit_counter < 4'd7) begin
                    bit_counter <= bit_counter + 1;
                    data_in[bit_counter] <= sda;
                    ack <= 1'b1;
                end else begin
                    bit_counter <= 4'd0;
                    addr <= data_in[6:4];
                    if (data_in[3]) begin
                        state <= 3'd4;
                        ack <= 1'b1;
                    end else begin
                        state <= 3'd5;
                        bit_counter <= 4'd0;
                        ack <= 1'b0;
                    end
                end
            end
            3'd4: begin
                if (!sda && scl) begin
                    state <= 3'd0;
                    bit_counter <= 4'd0;
                    ack <= 1'b1;
                end
            end
            3'd5: begin
                if (!sda && scl) begin
                    state <= 3'd6;
                    bit_counter <= 4'd0;
                    ack <= 1'b1;
                end
            end
            3'd6: begin
                if (sda && scl) begin
                    state <= 3'd7;
                    bit_counter <= 4'd0;
                    ack <= 1'b1;
                end else if (!sda && !scl) begin
                    state <= 3'd8;
                    bit_counter <= 4'd0;
                    ack <= 1'b1;
                end
            end
            3'd7: begin
                if (!sda && scl) begin
                    state <= 3'd0;
                    bit_counter <= 4'd0;
                    ack <= 1'b1;
                end
            end
            3'd8: begin
                if (bit_counter < 4'd7) begin
                    bit_counter <= bit_counter + 1;
                    data_in[bit_counter] <= sda;
                    ack <= 1'b1;
                end else begin
                    bit_counter <= 4'd0;
                    reg_data[addr] <= data_in;
                    state <= 3'd9;
                    ack <= 1'b1;
                end
            end
            3'd9: begin
                if (!sda && scl) begin
                    state <= 3'd0;
                    bit_counter <= 4'd0;
                    ack <= 1'b1;
                end
            end
            3'd10: begin
                if (!sda && scl) begin
                    state <= 3'd11;
                    bit_counter <= 4'd0;
                    ack <= 1'b1;
                end
            end
            3'd11: begin
                if (sda && scl) begin
                    state <= 3'd12;
                    bit_counter <= 4'd0;
                    ack <= 1'b1;
                end else if (!sda && !scl) begin
                    state <= 3'd10;
                    bit_counter <= 4'd0;
                    ack <= 1'b1;
                end
            end
            3'd12: begin
                if (bit_counter < 4'd7) begin
                    data_out[bit_counter] <= reg_data[addr][(bit_counter + 1)];
                    bit_counter <= bit_counter + 1;
                    ack <= 1'b1;
                end else begin
                    bit_counter <= 4'd0;
                    state <= 3'd13;
                    ack <= 1'b0;
                end
            end
            3'd13: begin
                if (!sda && scl) begin
                    state <= 3'd0;
                    bit_counter <= 4'd0;
                    ack <= 1'b1;
                end
            end
            default: begin
                state <= 3'd0;
                bit_counter <= 4'd0;
                addr <= 3'd0;
                data_out <= 8'h00;
                ack <= 1'b1;
            end
        endcase
    end
end

endmodule

这个代码实现了一个简单的 I2C Slave，支持读写 4 个 8 位的寄存器。您可以根据自己的需求进行修改。