can总线协议verilog代码

由于CAN总线协议涉及到硬件电路设计，因此需要使用硬件描述语言，如Verilog来实现。下面是一个简单的CAN总线接收器的Verilog代码示例：

module can_receiver(
    input clk,
    input rst,
    input can_rx,
    output reg [7:0] data,
    output reg [10:0] id,
    output reg rtr,
    output reg ext,
    output reg valid
);

reg [4:0] state;
reg [7:0] cnt;
reg [7:0] shift_reg;
reg [10:0] id_reg;
reg rtr_reg;
reg ext_reg;
reg valid_reg;

parameter IDLE = 0;
parameter START = 1;
parameter ARB = 2;
parameter DATA = 3;
parameter RTR = 4;
parameter EXT = 5;
parameter CRC = 6;
parameter ACK = 7;
parameter END = 8;

always @(posedge clk) begin
    if (rst) begin
        state <= IDLE;
        cnt <= 0;
        shift_reg <= 0;
        id_reg <= 0;
        rtr_reg <= 0;
        ext_reg <= 0;
        valid_reg <= 0;
        data <= 0;
        id <= 0;
        rtr <= 0;
        ext <= 0;
        valid <= 0;
    end else begin
        case (state)
            IDLE: begin
                if (can_rx == 0) begin
                    state <= START;
                    cnt <= 0;
                end
            end
            START: begin
                if (cnt == 10) begin
                    state <= ARB;
                    cnt <= 0;
                end else begin
                    cnt <= cnt + 1;
                end
            end
            ARB: begin
                if (cnt == 18) begin
                    state <= DATA;
                    cnt <= 0;
                end else begin
                    cnt <= cnt + 1;
                end
            end
            DATA: begin
                if (cnt < 8) begin
                    shift_reg <= {shift_reg[6:0], can_rx};
                end else if (cnt == 8) begin
                    id_reg[10:3] <= shift_reg;
                    rtr_reg <= shift_reg[2];
                    ext_reg <= shift_reg[1];
                end else if (cnt < 16) begin
                    id_reg[2:0] <= shift_reg;
                end else if (cnt < 24) begin
                    data <= {data[6:0], can_rx};
                end else if (cnt == 24) begin
                    state <= CRC;
                    cnt <= 0;
                end else begin
                    cnt <= cnt + 1;
                end
            end
            RTR: begin
                rtr <= rtr_reg;
                state <= EXT;
                cnt <= 0;
            end
            EXT: begin
                ext <= ext_reg;
                state <= ACK;
                cnt <= 0;
            end
            CRC: begin
                state <= ACK;
                cnt <= 0;
            end
            ACK: begin
                if (can_rx == 1) begin
                    state <= END;
                    cnt <= 0;
                end
            end
            END: begin
                if (cnt == 3) begin
                    valid <= 1;
                    id <= id_reg;
                    rtr <= rtr_reg;
                    ext <= ext_reg;
                    valid <= 1;
                    state <= IDLE;
                    cnt <= 0;
                end else begin
                    cnt <= cnt + 1;
                end
            end
        endcase
    end
end

endmodule

该代码实现了一个CAN总线接收器，可以接收CAN总线上的数据帧并解析出ID、RTR、EXT和DATA等信息。具体实现过程可以参考注释。需要注意的是，该代码只是一个简单的示例，实际应用中还需要根据具体的硬件平台和应用场景进行优化和修改。