用Verilog写一个uart

Verilog是一种用于描述数字电路的硬件描述语言，它可以用于描述UART（通用异步收发器）。下面是一个简单的Verilog代码模型：

module UART (input clk, 
             input rst, 
             input rx, 
             output reg tx, 
             output reg busy);
  
  parameter BAUD_RATE = 9600; 
  reg [7:0] rx_data; 
  reg [7:0] tx_data; 
  reg [11:0] counter; 
  reg [11:0] baud_counter; 
  reg start_bit; 
  reg [3:0] bit_counter; 
  reg rx_done; 
  reg tx_done; 
  
  always @(posedge clk) begin
    if (rst) begin 
      counter <= 0; 
      baud_counter <= 0; 
      start_bit <= 0; 
      bit_counter <= 0; 
      rx_done <= 0; 
      tx_done <= 0; 
      busy <= 0; 
    end else begin 
      if (baud_counter == BAUD_RATE-1) begin 
        baud_counter <= 0; 
        counter <= counter + 1; 
      end else 
        baud_counter <= baud_counter + 1; 
      if (start_bit) begin 
        if (bit_counter == 0) 
          tx <= 1'b0; 
        else if (bit_counter == 9) 
          tx_done <= 1; 
        else 
          tx <= tx_data[bit_counter-1]; 
        bit_counter <= bit_counter + 1; 
      end 
      if (rx & ~rx_done & (counter == 0)) begin 
        rx_data <= 0; 
        start_bit <= 1; 
        bit_counter <= 1; 
      end else if (start_bit & (counter == 1)) begin 
        rx_data <= {rx_data, rx}; 
        bit_counter <= bit_counter + 1; 
      end else if (bit_counter == 9) 
        rx_done <= 1; 
      busy <= ~rx_done | ~tx_done; 
    end 
  end 
  
endmodule 

这是一个简单的UART Verilog代码示例，它可以作为你开始写自己的UART模块的基础。注意，这仅仅是一个示例，可能不适用于所有的应用场景