HDLC协议 verilog

根据提供的引用内容，HDLC协议是一种常用的通讯协议，而Verilog是一种硬件描述语言，用于设计和验证数字电路。因此，可以使用Verilog来实现HDLC协议。

下面是一个简单的Verilog代码示例，用于实现HDLC协议的基本功能：

module hdlc_rx(
    input clk,
    input rst_n,
    input rx_data,
    input rx_valid,
    output reg frame_error,
    output reg [7:0] data_out,
    output reg frame_valid
);

reg [7:0] shift_reg;
reg [7:0] data_reg;
reg [2:0] bit_count;
reg frame_sync;

parameter IDLE = 3'b000;
parameter FLAG = 3'b001;
parameter DATA = 3'b010;
parameter ESCAPE = 3'b011;

reg [2:0] state;
reg [2:0] next_state;

always @(posedge clk or negedge rst_n) begin
    if (~rst_n) begin
        state <= IDLE;
        shift_reg <= 8'h00;
        data_reg <= 8'h00;
        bit_count <= 3'b000;
        frame_sync <= 1'b0;
        frame_error <= 1'b0;
        frame_valid <= 1'b0;
    end else begin
        state <= next_state;
        shift_reg <= {shift_reg[6:0], rx_data};
        data_reg <= {data_reg[6:0], rx_data};
        bit_count <= (state == DATA && bit_count == 3'b111) ? 3'b000 : bit_count + 1;
        frame_sync <= (shift_reg == 8'h7e) ? 1'b1 : (shift_reg == 8'h7d && frame_sync) ? 1'b1 : (shift_reg != 8'h7d) ? 1'b0 : frame_sync;
    end
end

always @(*) begin
    case (state)
        IDLE: begin
            next_state = (rx_valid && rx_data == 8'h7e) ? FLAG : IDLE;
        end
        FLAG: begin
            next_state = (rx_valid && rx_data == 8'h7e') ? FLAG : DATA;
        end
        DATA: begin
            next_state = (rx_valid && rx_data == 8'h7e) ? FLAG : (rx_valid && rx_data == 8'h7d) ? ESCAPE : DATA;
        end
        ESCAPE: begin
            next_state = (rx_valid) ? DATA : ESCAPE;
        end
        default: begin
            next_state = IDLE;
        end
    endcase
end

always @(posedge clk or negedge rst_n) begin
    if (~rst_n) begin
        data_out <= 8'h00;
    end else begin
        case (state)
            IDLE: begin
                data_out <= 8'h00;
            end
            FLAG: begin
                data_out <= 8'h00;
            end
            DATA: begin
                data_out <= data_reg;
            end
            ESCAPE: begin
                data_out <= rx_data ^ 8'h20;
            end
            default: begin
                data_out <= 8'h00;
            end
        endcase
    end
end

always @(posedge clk or negedge rst_n) begin
    if (~rst_n) begin
        frame_valid <= 1'b0;
    end else begin
        case (state)
            IDLE: begin
                frame_valid <= 1'b0;
            end
            FLAG: begin
                frame_valid <= 1'b0;
            end
            DATA: begin
                frame_valid <= (bit_count == 3'b000 && frame_sync) ? 1'b1 : 1'b0;
            end
            ESCAPE: begin
                frame_valid <= 1'b0;
            end
            default: begin
                frame_valid <= 1'b0;
            end
        endcase
    end
end

always @(posedge clk or negedge rst_n) begin
    if (~rst_n) begin
        frame_error <= 1'b0;
    end else begin
        case (state)
            IDLE: begin
                frame_error <= 1'b0;
            end
            FLAG: begin
                frame_error <= 1'b0;
            end
            DATA: begin
                frame_error <= (bit_count == 3'b000 && !frame_sync) ? 1'b1 : 1'b0;
            end
            ESCAPE: begin
                frame_error <= 1'b0;
            end
            default: begin
                frame_error <= 1'b0;
            end
        endcase
    end
end

endmodule

该代码实现了一个简单的HDLC接收器，包括帧同步、数据解码和错误检测等功能。需要注意的是，该代码仅用于演示Verilog实现HDLC协议的基本思路，实际应用中需要根据具体需求进行修改和优化。