apb总线verilog实现代码

以下是一个简单的APB总线的Verilog实现代码，仅供参考：

module apb_bus(
    input clk,
    input rstn,
    input PCLK,
    input PRESETn,
    input PSEL,
    input PENABLE,
    input [31:0] PADDR,
    input [31:0] PWRITE,
    output reg [31:0] PREAD,
    output reg PREADY,
    output reg PSLVERR
);

reg [31:0] mem [0:1023];
reg [31:0] data_out;
reg [31:0] addr;
reg [1:0] state;
wire [31:0] data_in;
wire [31:0] read_data;

assign read_data = mem[addr];

assign data_in = (PWRITE) ? PWRITE : read_data;

always @(posedge clk or negedge rstn) begin
    if(!rstn) begin
        PREADY <= 1'b0;
        PSLVERR <= 1'b0;
        state <= 2'b00;
        data_out <= 32'h0;
        addr <= 32'h0;
    end else begin
        case (state)
            2'b00: begin
                if(PSEL && PENABLE) begin
                    PREADY <= 1'b0;
                    PSLVERR <= 1'b0;
                    state <= 2'b01;
                end
            end
            2'b01: begin
                if(!PSEL || !PENABLE) begin
                    PREADY <= 1'b0;
                    PSLVERR <= 1'b1;
                    state <= 2'b00;
                end else begin
                    PREADY <= 1'b1;
                    PSLVERR <= 1'b0;
                    addr <= PADDR;
                    if(PWRITE) begin
                        data_out <= PWRITE;
                        state <= 2'b10;
                    end else begin
                        data_out <= read_data;
                        state <= 2'b11;
                    end
                end
            end
            2'b10: begin
                PREADY <= 1'b1;
                mem[addr] <= data_out;
                state <= 2'b00;
            end
            2'b11: begin
                PREADY <= 1'b1;
                PREAD <= data_out;
                state <= 2'b00;
            end
        endcase
    end
end

endmodule

这个实现包含了一个简单的APB总线模型，可以读写一个1024个32位的存储器，当PSEL和PENABLE同时为高时，总线将进入传输状态，根据PWRITE控制信号判断是否进行写操作，如果是写操作则将数据写入存储器中，否则将存储器中的数据读出并通过PREAD信号输出。在传输完成后，总线将会回到空闲状态。