verilog写一段axi4转spi协议的代码

以下是一段简单的Verilog代码，用于实现AXI4转SPI协议的转换：

module axi4_to_spi(
    input aclk,
    input aresetn,
    input [31:0] aresetn,
    input [31:0] araddr,
    input [1:0] arprot,
    input [31:0] arlen,
    input [31:0] arburst,
    input [31:0] awaddr,
    input [1:0] awprot,
    input [31:0] awlen,
    input [31:0] awburst,
    input [31:0] wdata,
    input [3:0] wstrb,
    input [31:0] wlast,
    input [1:0] wvalid,
    output [1:0] wready,
    output [31:0] rdata,
    output [1:0] rresp,
    output [1:0] rvalid,
    input [1:0] rready,
    output spi_clk,
    output spi_cs,
    output spi_mosi,
    input spi_miso
);

reg [31:0] spi_data;
reg [31:0] spi_ctrl;
reg [31:0] spi_status;
reg [31:0] spi_tx_data;
reg [31:0] spi_rx_data;

reg [2:0] spi_state;
localparam IDLE = 3'b000;
localparam CMD = 3'b001;
localparam DATA = 3'b010;
localparam WAIT = 3'b011;

assign rdata = spi_rx_data;
assign rresp = 2'b00;
assign rvalid = (spi_state == DATA) && (spi_status[0] == 1);

always @(posedge aclk) begin
    if (!aresetn) begin
        spi_state <= IDLE;
        spi_ctrl <= 0;
        spi_data <= 0;
        spi_status <= 0;
        spi_tx_data <= 0;
        spi_rx_data <= 0;
    end else begin
        case (spi_state)
            IDLE: begin
                if (wvalid[1:0] == 2'b11) begin
                    spi_state <= CMD;
                    spi_ctrl <= wdata;
                    spi_status <= {1'b1, 1'b0, 1'b0, 1'b0};
                    spi_tx_data <= 0;
                end
            end
            CMD: begin
                if (spi_status[2] == 1) begin
                    spi_state <= DATA;
                    spi_status <= {1'b0, 1'b1, 1'b0, 1'b0};
                    spi_tx_data <= wdata;
                end
            end
            DATA: begin
                if (spi_status[3] == 1) begin
                    spi_state <= WAIT;
                    spi_status <= {1'b0, 1'b0, 1'b1, 1'b0};
                    spi_tx_data <= 0;
                end
            end
            WAIT: begin
                if (spi_status[0] == 1) begin
                    spi_state <= IDLE;
                    spi_status <= {1'b0, 1'b0, 1'b0, 1'b1};
                    spi_tx_data <= 0;
                end
            end
        endcase
    end
end

always @(posedge spi_clk) begin
    case (spi_state)
        IDLE: begin
            spi_ctrl <= 0;
            spi_status <= {1'b0, 1'b0, 1'b0, 1'b0};
            spi_tx_data <= 0;
        end
        CMD: begin
            spi_ctrl <= spi_ctrl;
            spi_status <= spi_status;
            if (spi_status[1] == 1) begin
                spi_tx_data <= spi_ctrl[15:0];
            end else begin
                spi_tx_data <= 0;
            end
        end
        DATA: begin
            spi_ctrl <= spi_ctrl;
            spi_status <= spi_status;
            if (spi_status[2] == 1) begin
                spi_tx_data <= spi_data;
            end else begin
                spi_tx_data <= 0;
            end
        end
        WAIT: begin
            spi_ctrl <= spi_ctrl;
            spi_status <= spi_status;
            spi_tx_data <= 0;
        end
    endcase
end

always @(posedge spi_clk) begin
    case (spi_state)
        IDLE: begin
            spi_rx_data <= spi_rx_data;
            if (spi_status[0] == 1) begin
                spi_status <= {1'b0, 1'b0, 1'b0, 1'b0};
            end
        end
        CMD: begin
            spi_rx_data <= spi_rx_data;
            if (spi_status[1] == 1) begin
                spi_status <= {1'b0, 1'b1, 1'b0, 1'b0};
            end
        end
        DATA: begin
            spi_rx_data <= spi_rx_data;
            if (spi_status[2] == 1) begin
                spi_status <= {1'b0, 1'b0, 1'b1, 1'b0};
            end
            if (spi_status[1] == 1) begin
                spi_data <= spi_rx_data;
            end
        end
        WAIT: begin
            spi_rx_data <= spi_rx_data;
            if (spi_status[0] == 1) begin
                spi_status <= {1'b1, 1'b0, 1'b0, 1'b0};
            end
        end
    endcase
end

assign spi_cs = spi_status[2];

assign spi_mosi = (spi_status[1] == 1) ? spi_tx_data[7:0] : 0;

assign wready = (spi_state == WAIT) && (spi_status[1] == 0);

assign spi_clk = aclk;

endmodule

这段代码实现了一个简单的AXI4到SPI协议转换器。它包括一个状态机，用于控制数据的传输和处理。它还包括一个SPI接口，用于实际的数据传输。