verlog i2C 程序

以下是一份简单的Verilog I2C控制器程序，用于Master设备与Slave设备之间的通信：

module i2c_controller (
  input clk,
  input rst,
  input en,
  input [7:0] slave_addr,
  input [7:0] reg_addr,
  input [7:0] data_in,
  output [7:0] data_out,
  output sda,
  output scl
);

// 定义状态机的状态
typedef enum logic [3:0] {
  IDLE,
  START,
  ADDR,
  REG,
  RESTART,
  READ,
  WRITE,
  STOP
} state_t;

// 定义控制器的内部信号
reg [7:0] data_reg;
reg [3:0] state;
reg bit ack;
reg bit busy;
reg bit rw;
reg bit done;
reg bit sda_out;
reg bit scl_out;
reg [7:0] cnt;
wire sda_in;

// 模拟I2C总线的电平
assign sda = (busy && !done) ? sda_out : 1'b1;
assign scl = (busy && !done) ? scl_out : 1'b1;

// 状态机逻辑
always @(posedge clk or posedge rst) begin
  if (rst) begin
    state <= IDLE;
    ack <= 1'b0;
    busy <= 1'b0;
    done <= 1'b0;
    cnt <= 8'd0;
    sda_out <= 1'b1;
    scl_out <= 1'b1;
  end else if (en) begin
    case (state)
      IDLE: begin
        if (en) begin
          state <= START;
          busy <= 1'b1;
        end
      end
      START: begin
        sda_out <= 1'b0;
        if (cnt == 8'd7) begin
          state <= ADDR;
          cnt <= 8'd0;
        end else begin
          cnt <= cnt + 1;
        end
      end
      ADDR: begin
        if (cnt == 8'd7) begin
          sda_out <= 1'b1;
          state <= REG;
          cnt <= 8'd0;
        end else begin
          sda_out <= slave_addr[7-cnt];
          cnt <= cnt + 1;
        end
      end
      REG: begin
        if (cnt == 8'd7) begin
          sda_out <= 1'b1;
          state <= RESTART;
          cnt <= 8'd0;
        end else begin
          sda_out <= reg_addr[7-cnt];
          cnt <= cnt + 1;
        end
      end
      RESTART: begin
        sda_out <= 1'b0;
        if (cnt == 8'd7) begin
          state <= ADDR;
          cnt <= 8'd0;
        end else begin
          cnt <= cnt + 1;
        end
      end
      READ: begin
        if (cnt == 8'd7) begin
          ack <= 1'b0;
          sda_out <= 1'b1;
          state <= STOP;
          done <= 1'b1;
          cnt <= 8'd0;
        end else begin
          sda_out <= sda_in;
          cnt <= cnt + 1;
        end
      end
      WRITE: begin
        if (cnt == 8'd7) begin
          sda_out <= 1'b1;
          state <= STOP;
          done <= 1'b1;
          cnt <= 8'd0;
        end else begin
          sda_out <= data_reg[7-cnt];
          cnt <= cnt + 1;
        end
      end
      STOP: begin
        sda_out <= 1'b0;
        if (cnt == 8'd7) begin
          state <= IDLE;
          busy <= 1'b0;
          done <= 1'b0;
          cnt <= 8'd0;
        end else begin
          cnt <= cnt + 1;
        end
      end
    endcase
  end
end

// 从机应答逻辑
always @(posedge clk or posedge rst) begin
  if (rst) begin
    ack <= 1'b0;
  end else if (en) begin
    case (state)
      ADDR, REG: begin
        if (cnt == 8'd7) begin
          ack <= sda_in;
          cnt <= 8'd0;
        end else begin
          cnt <= cnt + 1;
        end
      end
    endcase
  end
end

// 数据输入输出逻辑
always @(posedge clk or posedge rst) begin
  if (rst) begin
    data_reg <= 8'd0;
  end else if (en) begin
    case (state)
      READ: begin
        data_reg <= {data_reg[6:0], sda_in};
      end
      WRITE: begin
        data_reg <= data_in;
      end
    endcase
  end
end

// 时钟控制逻辑
always @(posedge clk or posedge rst) begin
  if (rst) begin
    sda_out <= 1'b1;
    scl_out <= 1'b1;
  end else if (en) begin
    case (state)
      START, ADDR, REG, RESTART, READ, WRITE: begin
        if (cnt == 8'd3) begin
          scl_out <= 1'b1;
        end else if (cnt == 8'd7) begin
          sda_out <= (rw) ? 1'b1 : ack;
          scl_out <= 1'b1;
        end else if ((cnt == 8'd4) || (cnt == 8'd6)) begin
          scl_out <= 1'b0;
        end else if ((cnt == 8'd5) || (cnt == 8'd7)) begin
          sda_out <= (cnt == 8'd5) ? rw : sda_out;
          scl_out <= 1'b1;
        end
      end
      STOP: begin
        if (cnt == 8'd3) begin
          scl_out <= 1'b0;
          sda_out <= 1'b0;
        end else if (cnt == 8'd7) begin
          sda_out <= 1'b1;
          busy <= 1'b0;
        end else if ((cnt == 8'd4) || (cnt == 8'd6)) begin
          scl_out <= 1'b1;
        end else if (cnt == 8'd5) begin
          sda_out <= 1'b1;
          scl_out <= 1'b0;
        end
      end
    endcase
  end
end

// 从机输入逻辑
assign sda_in = (busy && !done) ? sda : 1'b1;

// 输出数据逻辑
assign data_out = (state == READ) ? data_reg : 8'd0;

endmodule

该程序实现了一个简单的I2C控制器，用于在Verilog中控制I2C总线上的Master设备与Slave设备之间的通信。该程序使用了状态机的概念，将I2C通信过程分为了不同的状态，通过时钟控制逻辑来控制总线上的时序信号，从而完成数据的发送和接收。此外，该程序还实现了从机的应答逻辑和数据输入输出逻辑。