UART连接ESP8266的verilog代码

以下是一个简单的Verilog代码，用于实现UART连接ESP8266：

module uart_esp8266(
  input CLK,
  input RST,
  input UART_RX,
  output reg UART_TX
);

reg [7:0] uart_data;
reg [3:0] uart_state;

localparam IDLE = 4'd0;
localparam START = 4'd1;
localparam RECEIVE = 4'd2;
localparam TRANSMIT = 4'd3;
localparam STOP = 4'd4;

always @(posedge CLK) begin
  if (RST) begin
    uart_data <= 8'b0;
    uart_state <= IDLE;
    UART_TX <= 1'b1;
  end else begin
    case(uart_state)
      IDLE: begin
        if (!UART_RX) begin
          uart_state <= START;
        end
      end
      START: begin
        uart_data <= 8'b0;
        uart_state <= RECEIVE;
      end
      RECEIVE: begin
        uart_data <= {uart_data[6:0], UART_RX};
        uart_state <= (uart_state == TRANSMIT) ? STOP : RECEIVE;
      end
      TRANSMIT: begin
        UART_TX <= uart_data[0];
        uart_data <= {1'b0, uart_data[7:1]};
        uart_state <= (uart_state == STOP) ? IDLE : TRANSMIT;
      end
      STOP: begin
        UART_TX <= 1'b1;
        uart_state <= IDLE;
      end
    endcase
  end
end

endmodule

这个模块在时钟上升沿时工作，包含一个有限状态机，用于处理UART通信。它接收UART_RX信号并将其存储在一个8位寄存器中，然后将数据发送到UART_TX输出端口。在发送每个字节之前，它会向UART_TX发送起始位，然后向UART_TX发送一个停止位。