教程目的

本教程介紹如何在ALINX Artix US+ AXAU25 FPGA開發板上，通過Multiboot實現多個 bitstream 的存儲與動態切換，并在配置失敗時自動回退至安全鏡像（Golden Image）。

適用對象

已掌握 FPGA 基礎開發（會寫Verilog、會生成bitstream）

熟悉 Vivado 工程流程

對 FPGA 配置機制尚不深入，希望進入系統級設計階段的學習者

Multiboot 功能概述

在基礎實驗中，FPGA 通常通過 JTAG 下載 bitstream，這種方式掉電后配置就丟失，亦無法實現遠程升級。Multiboot 通過將多個配置鏡像存儲在外部 Flash 中，使 FPGA 能夠在上電或運行過程中，從不同地址加載不同的 bitstream，并在異常情況下自動回退，保證系統可恢復。

Golden Image：固定存放在 Flash 的 0 地址，功能最小、穩定可靠，負責系統初始化與升級控制。

Multiboot Image：存放在 Flash 的其他地址，承載具體業務邏輯，可被升級或替換。

下圖展示了 FPGA Multiboot 機制的整體配置與啟動流程：FPGA 上電后默認從 Flash 0 地址加載 Golden Image，在滿足觸發條件后，通過 MultiBoot 機制嘗試從 Upper Address 加載 MultiBoot Image。當配置成功時運行 MultiBoot Image；若配置失敗，則觸發 Fallback 機制，自動回退并重新加載 Golden Image，以保證系統仍可正常運行。

（Multiboot 運行流程示意圖）

Multiboot 實現方式

AMD FPGA 支持兩種 Multiboot 實現方式，一種是在生成 bitstream 時嵌入 IPROG，另一種是通過用戶邏輯控制 ICAP 接口觸發重配置，本教程采用ICAP+IPROG的動態方式，可在 FPGA 運行過程中靈活控制重配置行為，更符合實際工程需求。

Multiboot 功能實現

使用硬件

開發板：ALINX AXAU25

FPGA：AMD Artix UltraScale+（XCAU25P）

啟動方式：SPI Flash（x4 模式）

該平臺原生支持 MultiBoot 與 Fallback。

（ALINX基于Artix UltraScale+ FPGA開發板AXAU25）

工程實現

Golden Image 設計

//===========================================================================
// Module name: led_test.v
//===========================================================================
`timescale 1ns / 1ps

module multiboot_top
(             
input  sys_clk_p,      // Difference system clock 200Mhz input on board
input  sys_clk_n,  
output reg  led            // LED,use for control the LED signal on board

 );
             
//define the time counter
reg [31:0]   timer;      
wire [31:0]   WBSTAR;      


//===========================================================================
//Differentia system clock to single end clock
//===========================================================================
wire        rst_n;
wire        sys_clk_buf;
wire        sys_clk;
wire        switch;
wire        switch_d0;
wire        switch_d1;
 IBUFGDS u_ibufg_sys_clk   //????????????????
     (
      .I  (sys_clk_p),
      .IB (sys_clk_n),
      .O  (sys_clk_buf  )
      ); 

  clk_wiz_0 syspll
   (
    // Clock out ports
    .clk_out1(sys_clk),     // output clk_out1
    // Status and control signals
    .locked(rst_n),       // output locked
   // Clock in ports
    .clk_in1(sys_clk_buf));               
    
    

vio_0 uu (
  .clk(sys_clk),                // input wire clk
  .probe_out0(switch),  // output wire [0 : 0] probe_out0
  .probe_out1(WBSTAR)  // output wire [31 : 0] probe_out1
);
//===========================================================================

//===========================================================================
  always @(posedge sys_clk)
    begin
      if (~rst_n)
          timer <= 32'd0;                     // when the reset signal valid,time counter clearing
      else if (timer == 32'd99_999_999)    //1 seconds count(200M-1=199999999) ?????200Mhz??????5ns??????0-199_999_999,??2*10^8??????
          timer <= 32'd0;                       //count done,clearing the time counter
      else
                    timer <= timer + 1'b1;            //timer counter = timer counter + 1????????????????
    end

//===========================================================================
// LED control
//===========================================================================
  always @(posedge sys_clk)
    begin
      if (~rst_n)
          led <= 0;                  //when the reset signal active
      else if (timer == 32'd99_999_999)   //time counter count to 1 sec,LED4 lighten
          led <= ~led;
    end

(* MARK_DEBUG="true" *)reg  ce ;
(* MARK_DEBUG="true" *)reg  write ;
(* MARK_DEBUG="true" *)reg [31:0]  icap_in ;
(* MARK_DEBUG="true" *)wire [31:0]  icap_in_wire ;

   ICAPE3 #(
      .DEVICE_ID(32'h04A64093),     // Specifies the pre-programmed Device ID value to be used for simulation
                                    // purposes.
      .ICAP_AUTO_SWITCH("DISABLE"), // Enable switch ICAP using sync word.
      .SIM_CFG_FILE_NAME("NONE")    // Specifies the Raw Bitstream (RBT) file to be parsed by the simulation
                                    // model.
   )
   ICAPE3_inst (
      .AVAIL(),     // 1-bit output: Availability status of ICAP.
      .O(O),             // 32-bit output: Configuration data output bus.
      .PRDONE(),   // 1-bit output: Indicates completion of Partial Reconfiguration.
      .PRERROR(), // 1-bit output: Indicates error during Partial Reconfiguration.
      .CLK(sys_clk),         // 1-bit input: Clock input.
      .CSIB(ce),       // 1-bit input: Active-Low ICAP enable.
      .I(icap_in_wire),             // 32-bit input: Configuration data input bus.
      .RDWRB(write)      // 1-bit input: Read/Write Select input.
   );

localparam        [31:0]        DUMMY_WORD                = 32'hFFFFFFFF;
localparam        [31:0]        SYNC_WORD            = 32'hAA995566;
localparam        [31:0]        TYPE1_NOOP                = 32'h20000000;
localparam        [31:0]        TYPE1_WBSTAR        = 32'h30020001;
localparam        [31:0]        TYPE1_CMD                  = 32'h30008001;
localparam        [31:0]        IPROG_CMD                  = 32'h0000000F;

// localparam  [31:0]  WBSTAR        = 32'h04000000;

(* MARK_DEBUG="true" *)reg [3:0]  state ;


assign icap_in_wire = {icap_in[3*8+0],icap_in[3*8+1],icap_in[3*8+2],icap_in[3*8+3],icap_in[3*8+4],icap_in[3*8+5],icap_in[3*8+6],icap_in[3*8+7],
                      icap_in[2*8+0],icap_in[2*8+1],icap_in[2*8+2],icap_in[2*8+3],icap_in[2*8+4],icap_in[2*8+5],icap_in[2*8+6],icap_in[2*8+7],
                      icap_in[1*8+0],icap_in[1*8+1],icap_in[1*8+2],icap_in[1*8+3],icap_in[1*8+4],icap_in[1*8+5],icap_in[1*8+6],icap_in[1*8+7],
                      icap_in[0*8+0],icap_in[0*8+1],icap_in[0*8+2],icap_in[0*8+3],icap_in[0*8+4],icap_in[0*8+5],icap_in[0*8+6],icap_in[0*8+7]};


always @(posedge sys_clk ) begin
  if (~rst_n)  begin
    state <= 0 ;
    ce <= 0 ;
    write <= 0 ;
    icap_in <= DUMMY_WORD ;
  end
  else begin
    case (state)
      0: begin
        if (switch) begin
          state <= 1 ;
          icap_in <= DUMMY_WORD ;   //Dummy word
          write <= 0 ;
          ce <= 0 ;
        end
      end
      1: begin
        state <= 2 ;
        icap_in <= SYNC_WORD ;   //sync word
      end
      2: begin
        state <= 3 ;
        icap_in <= TYPE1_NOOP ;   //Type 1 NOOP
      end
      3: begin
        state <= 4 ;
        icap_in <= TYPE1_WBSTAR ;   //Type 1 Write 1 words to WBSTAR
      end
      4: begin
        state <= 5 ;
        icap_in <= WBSTAR ;   //Warm boot start address (Load the desired address)
      end
      5: begin
        state <= 6 ;
        icap_in <= TYPE1_CMD ;   //Type 1 Write 1 words to CMD
      end
      6: begin
        state <= 7 ;
        icap_in <= IPROG_CMD ;   //IPROG command
      end
      7: begin
        state <= 8 ;
        icap_in <= TYPE1_NOOP ;   //Type 1 NOOP
      end
      8: begin
        state <= 8 ;
        write <= 1 ;
        ce <= 1 ;
        icap_in <= 0 ;
      end
      default: begin
        state <= 0 ;
        ce <= 1 ;
        write <= 1 ;
        icap_in <= DUMMY_WORD ;
      end
    endcase
  end
end

    
endmodule

XDC 約束
############## clock define##################
create_clock -period 5.000 [get_ports sys_clk_p]
set_property PACKAGE_PIN T24 [get_ports sys_clk_p]
set_property PACKAGE_PIN U24 [get_ports sys_clk_n]
set_property IOSTANDARD DIFF_SSTL18_I [get_ports sys_clk_n]



##############LED define##################
set_property PACKAGE_PIN W21 [get_ports led]
set_property IOSTANDARD LVCMOS18 [get_ports led]


set_property CONFIG_MODE SPIx4 [current_design]
set_property BITSTREAM.CONFIG.CONFIGRATE 85.0 [current_design]
set_property BITSTREAM.CONFIG.SPI_32BIT_ADDR YES [current_design]
set_property BITSTREAM.CONFIG.SPI_BUSWIDTH 4 [current_design]
set_property BITSTREAM.CONFIG.SPI_FALL_EDGE YES [current_design]
set_property BITSTREAM.CONFIG.CONFIGFALLBACK ENABLE [current_design]

set_property BITSTREAM.GENERAL.COMPRESS TRUE [current_design]

Multiboot Image 設計

`timescale 1ns / 1ps 
module multiboot(
//Differential system clock
    input sys_clk_p,
    input sys_clk_n,
    input rst_n,
(* MARK_DEBUG="true" *)    output reg [1:0] led
    );
(* MARK_DEBUG="true" *)reg[31:0] timer_cnt;
wire sys_clk ;

IBUFDS IBUFDS_inst (
      .O(sys_clk),   // 1-bit output: Buffer output
      .I(sys_clk_p),   // 1-bit input: Diff_p buffer input (connect directly to top-level port)
      .IB(sys_clk_n)  // 1-bit input: Diff_n buffer input (connect directly to top-level port)
   );

always@(posedge sys_clk)
begin
    if (!rst_n)
    begin
      led <= 2'b0 ;
    end
    else if(timer_cnt <= 32'd100_000_000)
    begin
        led <= 2'b10;
    end
    else begin
         led <= 2'b01;
    end
end

always@(posedge sys_clk)begin
    if(!rst_n)begin
        timer_cnt <= 32'b0;
    end
    else if(timer_cnt >= 32'd199_999_999)   //1 second counter, 200M-1=199_999_999
    begin
        timer_cnt <= 32'd0;
    end
    else begin
        timer_cnt <= timer_cnt + 1;
    end
end


endmodule
xdc約束
set_property PACKAGE_PIN T24 [get_ports sys_clk_p]
set_property PACKAGE_PIN N26 [get_ports rst_n]
set_property PACKAGE_PIN W21 [get_ports led]
set_property IOSTANDARD LVCMOS18 [get_ports {led[1]}]
set_property IOSTANDARD LVCMOS18 [get_ports {led[0]}]
set_property IOSTANDARD LVCMOS18 [get_ports rst_n]
set_property IOSTANDARD DIFF_SSTL18_I [get_ports sys_clk_p]

set_property PACKAGE_PIN AC16 [get_ports {led[0]}]
set_property PACKAGE_PIN W21 [get_ports {led[1]}]

create_clock -period 5.000 -name sys_clk_p -waveform {0.000 2.500} [get_ports sys_clk_p]

set_property BITSTREAM.CONFIG.CONFIGFALLBACK ENABLE [current_design]
set_property BITSTREAM.GENERAL.COMPRESS TRUE [current_design]
set_property BITSTREAM.CONFIG.SPI_BUSWIDTH 4 [current_design]
set_property BITSTREAM.CONFIG.SPI_32BIT_ADDR YES [current_design]

設備的 ID 是固定按照提供資料查詢相關操作設備 ID

下方列表是通過 ICAP 接口進行 IPROG 中需要執行的命令

通過 Vivado 將需要固化的兩個 bit 文件合成一個燒寫文件，燒寫完成斷電重新上電即可。

實驗結果

默認加載 Golden Image，LED 1閃爍

通過 VIO 設置

switch=1，WBSTAR=0x0080_0000（我們在 Flash 中存放的第二個 Multiboot Image 的初始地址），等待一段時間，LED 1、LED 2 交替閃爍，MultiBoot Image 切換成功。

參考文檔

UltraScale Architecture Configuration User Guide (UG570)

Vivado Design Suite 用戶指南: 編程和調試 (UG908)

歡迎您聯系我們，一起交流技術。

審核編輯 黃宇