用verilog写rs485串口通信接收端和发送端代码不用串口ip

以下是用verilog语言编写的RS485串口通信接收端和发送端代码示例：

接收端代码：

module rs485_receiver( input clk, input rst, input rx, output reg [7:0] data_out, output reg frame_error, output reg parity_error, output reg overrun_error, output reg valid_data );

parameter IDLE = 2'b00; parameter START = 2'b01; parameter DATA = 2'b10; parameter STOP = 2'b11;

reg [1:0] state; reg [7:0] data; reg [7:0] shift_reg; reg [2:0] bit_count; reg parity;

assign data_out = shift_reg; assign frame_error = (state == START); assign parity_error = (state == STOP); assign overrun_error = (state == DATA); assign valid_data = (state == STOP);

always @(posedge clk) begin if (rst) begin state <= IDLE; data <= 8'b0; shift_reg <= 8'b0; bit_count <= 3'b0; parity <= 1'b0; end else begin case (state) IDLE: begin if (!rx) begin state <= START; data <= 8'b0; bit_count <= 3'b0; parity <= 1'b0; end end START: begin if (rx) begin state <= IDLE; end else begin state <= DATA; bit_count <= 3'b0; parity <= 1'b0; end end DATA: begin if (bit_count == 3'b8) begin state <= STOP; end else begin data[bit_count] <= rx; bit_count <= bit_count + 1; parity <= parity ^ rx; end end STOP: begin if (rx) begin shift_reg <= data; state <= IDLE; end else begin state <= START; end end endcase end end

endmodule

发送端代码：

module rs485_transmitter( input clk, input rst, input [7:0] data_in, input enable, output reg tx );

parameter IDLE = 2'b00; parameter START = 2'b01; parameter DATA = 2'b10; parameter STOP = 2'b11;

reg [1:0] state; reg [7:0] data; reg [2:0] bit_count; reg parity;

assign tx = (state == DATA) ? data[bit_count] : 1'b1;

always @(posedge clk) begin if (rst) begin state <= IDLE; data <= 8'b0; bit_count <= 3'b0; parity <= 1'b0; end else begin case (state) IDLE: begin if (enable) begin state <= START; data <= data_in; bit_count <= 3'b0; parity <= 1'b0; end end START: begin state <= DATA; bit_count <= 3'b0; parity <= 1'b0; end DATA: begin if (bit_count == 3'b8) begin state <= STOP; end else begin bit_count <= bit_count + 1; parity <= parity ^ data[bit_count]; end end STOP: begin state <= IDLE; end endcase end end

endmodule