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FPGA零基础学习：SPI 协议驱动设计

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SPI 协议驱动设计

作者：郝旭帅校对：陆辉

本篇实现基于叁芯智能科技的SANXIN -B01 FPGA开发板，以下为配套的教程，如有入手开发板，可以登录官方淘宝店购买，还有配套的学习视频。

SANXIN-B01 Verilog教程-郝旭帅团队

SPI是串行外设接口(Serial Peripheral Interface)的缩写。SPI，是一种高速的，全双工，同步的通信总线，并且在芯片的管脚上只占用四根线，节约了芯片的管脚，同时为PCB的布局上节省空间，提供方便，正是出于这种简单易用的特性，如今越来越多的芯片集成了这种通信协议。

SPI的通信原理很简单，它以主从方式工作，这种模式通常有一个主设备和一个或多个从设备，中间靠三线或者四线连接（三线时为单向传输或者数据线双向传输）。所有基于SPI的设备共有的，它们是MISO、MOSI、SCLK、CS。

MISO– Master Input Slave Output,主设备数据输入，从设备数据输出。

MOSI– Master Output Slave Input,主设备数据输出，从设备数据输入。

SCLK – Serial Clock,时钟信号，由主设备产生。

CS – Chip Select,从设备使能信号，由主设备控制。

cs是从芯片是否被主芯片选中的控制信号，也就是说只有片选信号为预先规定的使能信号时(高电位或低电位)，主芯片对此从芯片的操作才有效。这就使在同一条总线上连接多个spi设备成为可能。

通讯是通过数据交换完成的，由sclk提供时钟脉冲，mosi、miso则基于此脉冲完成数据传输。数据输出通过 mosi线，数据在时钟上升沿或下降沿时改变，在紧接着的下降沿或上升沿被读取。完成一位数据传输，输入也使用同样原理。因此，至少需要N次时钟信号的改变(上沿和下沿为一次)，才能完成N位数据的传输。

spi通信有四种不同的模式，不同的从设备可能在出厂时就已经配置为某种模式。通信的双方必须是工作在同一模式下，所以我们可以对主设备的spi模式进行配置，通过CPOL（时钟极性）和CPHA（时钟相位）来控制我们主设备的通信模式。

mode0：CPOL=0，CPHA=0；

mode1：CPOL=0，CPHA=1；

mode2：CPOL=1，CPHA=0；

mode3：CPOL=1，CPHA=1；

时钟极性CPOL是用来配置SCLK在空闲时，应该处于的状态；时钟相位CPHA用来配置在第几个边沿进行采样。

CPOL=0，表示在空闲状态时，时钟SCLK为低电平。

CPOL=1，表示在空闲状态时，时钟SCLK为高电平。

CPHA=0，表示数据采样是在第1个边沿。

CPHA=1，表示数据采样是在第2个边沿。

即：

CPOL=0，CPHA=0：此时空闲态时，SCLK处于低电平，数据采样是在第1个边沿，也就是SCLK由低电平到高电平的跳变，所以数据采样是在上升沿，数据发送是在下降沿。

CPOL=0，CPHA=1：此时空闲态时，SCLK处于低电平，数据发送是在第1个边沿，也就是SCLK由低电平到高电平的跳变，所以数据采样是在下降沿，数据发送是在上升沿。

CPOL=1，CPHA=0：此时空闲态时，SCLK处于高电平，数据采集是在第1个边沿，也就是SCLK由高电平到低电平的跳变，所以数据采集是在下降沿，数据发送是在上升沿。

CPOL=1，CPHA=1：此时空闲态时，SCLK处于高电平，数据发送是在第1个边沿，也就是SCLK由高电平到低电平的跳变，所以数据采集是在上升沿，数据发送是在下降沿。

硬件简介

FLASH闪存的英文名称是"Flash Memory"，一般简称为"Flash"，它属于内存器件的一种，是一种非易失性( Non-Volatile )内存。

在开发板上有一块flash（M25P16），用来保存FPGA的硬件配置信息，也可以用来存储用户的应用程序或数据。

M25P16是一款带有写保护机制和高速SPI总线访问的2M字节串行Flash存储器，该存储器主要特点：2M字节的存储空间，分32个扇区，每个扇区256页，每页256字节；能单个扇区擦除和整片擦除；每扇区擦写次数保证10万次、数据保存期限至少20年。

C（serial clock：串行时钟）为D和Q提供了数据输入或者输出的时序。D的数据总是在C的上升沿被采样。Q的数据在C的下降沿被输出。

（Chip Select：芯片选择端），当输入为低时，该芯片被选中，可以允许进行读写操作。当输入为高时，该芯片被释放，不能够进行操作。

对于H——o——l——d——和W——，为保持功能和硬件写保护功能，在本设计中不使用此管脚，在硬件设计时，这两个管脚全部被拉高了，即全部失效。

flash采用spi的通信协议，flash当做从机。serial clcok等效于spi中的sclk，chip select等效于spi中的cs，D等效于spi中的mosi，Q等效于spi中的miso。

flash可以支持mode0和mode3，这两种模式中，都是在时钟的上升沿采样，在时钟的下降沿发送数据。

flash的每一页都可以被写入，但是写入只能是把1改变为0。擦除可以把0改变为1。所以在正常写入数据之前，都要将flash进行擦除。

flash的命令表如下：

下面介绍几个常用的命令。

RDID（Read Identification ：读ID）：发送命令RDID（9F），然后接收第1个字节的memory type（20H），第二个字节的memory capacity（15H）。后续的字节暂不关心。

WREN（Write Enable ：写使能）：在任何写或者擦除的命令之前，都必须首先打开写使能。打开写使能为发送命令WREN（06h）。

RDSR（Read Status Register：读状态寄存器）：发送命令RDSR（05h），然后返回一个字节的状态值。

状态寄存器的格式如下：

WIP（Write In Progress bit）表示flash内部是否正在进行内部操作，写和擦除都会导致flash内部进行一段时间的工作，在内部工作期间，外部的命令会被忽略，所以在进行任何命令之前，都需要查看flash内部是否正在工作。WIP为1时，表示flash内部正在工作；WIP为0时，表示flash内部没有在工作。

READ（Read DATA Bytes：读数据）：发送命令READ（03H），后续发送3个字节的地址，然后就可以接收数据，内部的地址会不断递增。一个读命令就可以把整个flash全部读完。

PP（Page Program ：页编写）：发送命令PP（02H），接着发送3个字节的地址，然后发送数据即可。切记所写的数据不能超过本页的地址范围。

SE（Sector Erase ：扇区擦除）：发送命令SE（D8H），接着发送3个字节的地址。

BE（Bulk Erase：整片擦除）：发送命令BE（C7H）。

关于flash的其他的介绍，可以参考03_芯片手册->FLASH->M25P16.pdf。

设计要求

设计flash（M25P16）控制器。

设计分析

根据M25P16的数据手册得知，其接口为spi接口，且支持模式0和模式3，本设计中选择模式0。

输入时序图如下：

输出时序如下：

时序图中所对应的符号说明：

根据输入和输出的时序图以及参数表，将SPI的时钟的频率定为10MHz。

在设计中，FPGA作为主机，M25P16作为从机。

架构设计和信号说明

此模块命名为m25p16_drive。

二级模块（分模块）（第一页）

二级模块（分模块）（第二页）

设计中，各个命令单独写出控制器，通过多路选择器选择出对应的命令，然后控制spi_8bit_drive将数据按照spi的协议发送出去。各个命令的脉冲通过ctrl模块进行控制各个命令控制器，写入的数据首先写入到写缓冲区，读出的数据读出后写入到读缓冲区。

暂不分配的端口，在应用时都是由上游模块进行控制，本设计测试时，编写上游模块进行测试。

各个模块的功能，和连接线的功能在各个模块设计中说明。

spi_8bit_drive设计实现

本模块负责将8bit的并行数据按照spi协议发送出去，以及负责按照spi协议接收数据，将接收的数据（8bit）并行传输给各个模块。

spi_send_en为发送数据使能信号（脉冲信号），spi_send_data为所要发送数据，spi_send_done为发送完成信号（脉冲信号）。

spi_read_en为接收数据使能信号（脉冲信号），spi_read_data为所接收的数据，spi_read_done为接收完成信号（脉冲信号）。

module spi_8bit_drive (  input   wire              clk,  input   wire              rst_n,  input   wire              spi_send_en,  input   wire  [7:0]       spi_send_data,  output  reg               spi_send_done,  input   wire              spi_read_en,  output  reg   [7:0]       spi_read_data,  output  reg               spi_read_done,  output  wire              spi_sclk,  output  wire              spi_mosi,  input   wire              spi_miso);  reg           [8:0]       send_data_buf;  reg           [3:0]       send_cnt;  reg                       rec_en;  reg                       rec_en_n;  reg           [3:0]       rec_cnt;  reg           [7:0]       rec_data_buf;  always @ (negedge clk, negedge rst_n) begin    if (rst_n == 1'b0)      send_data_buf <= 9'd0;    else      if (spi_send_en == 1'b1)        send_data_buf <= {spi_send_data, 1'b0};      else        send_data_buf <= send_data_buf;  end  always @ (negedge clk, negedge rst_n) begin    if (rst_n == 1'b0)      send_cnt <= 4'd8;    else      if (spi_send_en == 1'b1)        send_cnt <= 4'd0;      else        if (send_cnt < 4'd8)          send_cnt <= send_cnt + 1'b1;        else          send_cnt <= send_cnt;  end  assign spi_mosi = send_data_buf[8 - send_cnt];  assign spi_sclk = (send_cnt < 4'd8 || rec_en_n == 1'b1) ? clk : 1'b0;  always @ (negedge clk, negedge rst_n) begin    if (rst_n == 1'b0)      spi_send_done <= 1'b0;    else      if (send_cnt == 4'd7)        spi_send_done <= 1'b1;      else        spi_send_done <= 1'b0;  end  always @ (posedge clk, negedge rst_n) begin    if (rst_n == 1'b0)      rec_en <= 1'b0;    else      if (spi_read_en == 1'b1)        rec_en <= 1'b1;      else        if (rec_cnt ==  4'd7)          rec_en <= 1'b0;        else          rec_en <= rec_en;  end  always @ (negedge clk, negedge rst_n) begin    if (rst_n == 1'b0)      rec_en_n <= 1'b0;    else      rec_en_n <= rec_en;  end  always @ (posedge clk, negedge rst_n) begin    if (rst_n == 1'b0)      rec_data_buf <= 8'd0;    else      if (rec_en == 1'b1)        rec_data_buf <= {rec_data_buf[6:0], spi_miso};      else        rec_data_buf <=rec_data_buf;  end  always @ (posedge clk, negedge rst_n) begin    if (rst_n == 1'b0)      rec_cnt <= 4'd0;    else      if (rec_en == 1'b1)        rec_cnt <= rec_cnt + 1'b1;      else        rec_cnt <= 4'd0;  end  always @ (posedge clk, negedge rst_n) begin    if (rst_n == 1'b0)      spi_read_done <= 1'b0;    else      if (rec_cnt == 4'd8)        spi_read_done <= 1'b1;      else        spi_read_done <= 1'b0;  end  always @ (posedge clk, negedge rst_n) begin    if (rst_n == 1'b0)      spi_read_data <= 8'd0;    else      if (rec_cnt == 4'd8)        spi_read_data <= rec_data_buf;      else        spi_read_data <= spi_read_data;  endendmodule

在发送逻辑控制中，全部的信号采用下降沿驱动。利用外部给予的spi_send_en作为启动信号，启动send_cnt。send_cnt在不发送数据时为8，发送数据时，从0到7。

在接收逻辑中，全部的信号采用上升沿驱动。利用外部给予的spi_read_en作为启动信号，启动rec_en，经过移位接收数据。

在spi_sclk输出时，采用组合逻辑。由于设计采用spi的模式0，故而spi_sclk不发送或者接收数据时为0，接收数据时为时钟信号。因为要求为模式0，所以在接收数据时，spi_sclk的输出不能够先有下降沿，即要求spi_sclk的控制信号不能由上升沿信号驱动，所以将rec_en同步到下降沿的rec_en_n。

仿真代码为：

`timescale 1ns/1psmodule spi_8bit_drive_tb;  reg               clk;  reg               rst_n;  reg               spi_send_en;  reg     [7:0]     spi_send_data;  wire              spi_send_done;  reg               spi_read_en;  wire    [7:0]     spi_read_data;  wire              spi_read_done;  wire              spi_sclk;  wire              spi_mosi;  reg               spi_miso;  spi_8bit_drive spi_8bit_drive_inst(      .clk              (clk),      .rst_n            (rst_n),      .spi_send_en      (spi_send_en),      .spi_send_data    (spi_send_data),      .spi_send_done    (spi_send_done),      .spi_read_en      (spi_read_en),      .spi_read_data    (spi_read_data),      .spi_read_done    (spi_read_done),      .spi_sclk         (spi_sclk),      .spi_mosi         (spi_mosi),      .spi_miso         (spi_miso)  );  initial clk = 1'b0;  always # 50 clk = ~clk;  initial begin    rst_n = 1'b0;    spi_send_en = 1'b0;    spi_send_data = 8'd0;    spi_read_en = 1'b0;    spi_miso = 1'b0;    # 201    rst_n = 1'b1;    # 200    @ (posedge clk);    # 2;    spi_send_en = 1'b1;    spi_send_data = {$random} % 256;    @ (posedge clk);    # 2;    spi_send_en = 1'b0;    spi_send_data = 8'd0;    @ (posedge spi_send_done);    # 2000    @ (posedge clk);    # 2;    spi_read_en = 1'b1;    @ (posedge clk);    # 2;    spi_read_en = 1'b0;    @ (posedge spi_read_done);    # 200    $stop;  end  always @ (negedge clk) spi_miso <= {$random} % 2;endmodule

在仿真中，将时钟设置为10MHz。

所有的信号采用上升沿驱动。发送一个8bit的随机数值，接收一个8bit的随机数值。

spi_miso信号为从机下降沿驱动信号。

通过RTL仿真，可以看出发送和接收全部正常。

mux7_1设计实现

本模块负责将7个命令模块发出的命令（写使能、写数据和读使能）经过选择发送给spi_8bit_drive模块。

module mux7_1 (  input     wire          rdsr_send_en,  input     wire    [7:0] rdsr_send_data,  input     wire          rdsr_read_en,  input     wire          pp_send_en,  input     wire    [7:0] pp_send_data,  input     wire          wren_send_en,  input     wire    [7:0] wren_send_data,  input     wire          be_send_en,  input     wire    [7:0] be_send_data,  input     wire          se_send_en,  input     wire    [7:0] se_send_data,  input     wire          rdid_send_en,  input     wire    [7:0] rdid_send_data,  input     wire          rdid_read_en,  input     wire          read_send_en,  input     wire    [7:0] read_send_data,  input     wire          read_read_en,  input     wire    [2:0] mux_sel,                   output    reg           spi_send_en,  output    reg     [7:0] spi_send_data,  output    reg           spi_read_en);  always @ * begin    case (mux_sel)      3'd0    : begin         spi_send_en = rdsr_send_en;         spi_send_data = rdsr_send_data;         spi_read_en = rdsr_read_en;       end      3'd1    : begin         spi_send_en = pp_send_en;         spi_send_data = pp_send_data;         spi_read_en = 1'b0;       end      3'd2    : begin         spi_send_en = wren_send_en;         spi_send_data = wren_send_data;         spi_read_en = 1'b0;       end      3'd3    : begin         spi_send_en = be_send_en;         spi_send_data = be_send_data;         spi_read_en = 1'b0;       end      3'd4    : begin         spi_send_en = se_send_en;         spi_send_data = se_send_data;         spi_read_en = 1'b0;       end      3'd5    : begin         spi_send_en = rdid_send_en;         spi_send_data = rdid_send_data;         spi_read_en = rdid_read_en;       end      3'd6    : begin         spi_send_en = read_send_en;         spi_send_data = read_send_data;         spi_read_en = read_read_en;       end      default : begin         spi_send_en = 1'b0;         spi_send_data = 8'd0;         spi_read_en = 1'b0;       end    endcase  endendmodule

在设计中，有的命令模块不需要进行读取（pp和se等等），此时将输出的读使能信号输出为低电平。

be设计实现

该模块接收到be_en（整片擦除的脉冲信号）信号后，发送对应的使能和数据，等待发送完成脉冲。发送完成后，输出擦除完成的脉冲。

module be (  input     wire            clk,  input     wire            rst_n,  input     wire            be_en,  output    reg             be_done,  output    reg             be_send_en,  output    wire    [7:0]   be_send_data,  input     wire            spi_send_done);  always @ (posedge clk, negedge rst_n) begin    if (rst_n == 1'b0)      be_send_en <= 1'b0;    else      be_send_en <= be_en;  end  assign be_send_data = 8'hc7;  always @ (posedge clk, negedge rst_n) begin    if (rst_n == 1'b0)      be_done <= 1'b0;    else      be_done <= spi_send_done;  endendmodule

整片擦除的命令为8’hc7。

wren设计实现

该模块接收到wren_en（打开flash内部的写使能的脉冲信号）信号后，发送对应的使能和数据，等待发送完成脉冲。发送完成后，输出擦除完成的脉冲。

module wren (  input     wire            clk,  input     wire            rst_n,  input     wire            wren_en,  output    reg             wren_done,  output    reg             wren_send_en,  output    wire    [7:0]   wren_send_data,  input     wire            spi_send_done);  always @ (posedge clk, negedge rst_n) begin    if (rst_n == 1'b0)      wren_send_en <= 1'b0;    else      wren_send_en <= wren_en;  end  assign wren_send_data = 8'h06;  always @ (posedge clk, negedge rst_n) begin    if (rst_n == 1'b0)      wren_done <= 1'b0;    else      wren_done <= spi_send_done;  endendmodule

打开flash内部写使能的命令码为8’h06。

se设计实现

该模块接收到se_en（擦除扇区的写使能的脉冲信号）信号后，发送对应的使能和数据，等待发送完成脉冲。发送完成后，接着发送高八位地址，中间八位地址和低八位地址。全部发送完成后，发送se_done信号。

该模块采用状态机实现。SE_STATE（扇区擦除命令发送）、H_ADDR（高八位地址发送）、M_ADDR（中间八位地址发送）、L_ADDR（低八位地址发送）、SE_DONE（扇区擦除完成）。所有的脉冲信号在未标注的时刻，输出全部为0。

设计代码为：

module se (  input   wire                clk,  input   wire                rst_n,  input   wire                se_en,  input   wire      [23:0]    se_addr,  output  reg                 se_done,  output  reg                 se_send_en,  output  reg       [7:0]     se_send_data,  input   wire                spi_send_done);  localparam      SE_STATE    = 5'b00001;  localparam      H_ADDR      = 5'b00010;  localparam      M_ADDR      = 5'b00100;  localparam      L_ADDR      = 5'b01000;  localparam      SE_DONE     = 5'b10000;  reg               [4:0]     c_state;  reg               [4:0]     n_state;  always @ (posedge clk, negedge rst_n) begin    if (rst_n == 1'b0)      c_state <= SE_STATE;    else      c_state <= n_state;  end  always @ * begin    case (c_state)      SE_STATE    :   begin        if (se_en == 1'b0)          n_state = SE_STATE;        else          n_state = H_ADDR;      end      H_ADDR      :   begin        if (spi_send_done == 1'b0)          n_state = H_ADDR;        else          n_state = M_ADDR;      end      M_ADDR      :   begin        if (spi_send_done == 1'b0)          n_state = M_ADDR;        else          n_state = L_ADDR;      end      L_ADDR      :   begin        if (spi_send_done == 1'b0)          n_state = L_ADDR;        else          n_state = SE_DONE;      end      SE_DONE     :   begin        if (spi_send_done == 1'b0)          n_state = SE_DONE;        else          n_state = SE_STATE;      end      default     :     n_state = SE_STATE;    endcase  end  always @ (posedge clk, negedge rst_n) begin    if (rst_n == 1'b0)      se_send_en <= 1'b0;    else      case (c_state)        SE_STATE    :   begin          if (se_en == 1'b1)            se_send_en <= 1'b1;          else            se_send_en <= 1'b0;        end        H_ADDR      :   begin          if (spi_send_done == 1'b1)            se_send_en <= 1'b1;          else            se_send_en <= 1'b0;        end        M_ADDR      :   begin          if (spi_send_done == 1'b1)            se_send_en <= 1'b1;          else            se_send_en <= 1'b0;        end        L_ADDR      :   begin          if (spi_send_done == 1'b1)            se_send_en <= 1'b1;          else            se_send_en <= 1'b0;        end        SE_DONE     :   begin          se_send_en <= 1'b0;        end        default     :   se_send_en <= 1'b0;      endcase  end  always @ (posedge clk, negedge rst_n) begin    if (rst_n == 1'b0)      se_send_data <= 8'd0;    else      case (c_state)        SE_STATE    :   begin          if (se_en == 1'b1)            se_send_data <= 8'hd8;          else            se_send_data <= 8'd0;        end        H_ADDR      :   begin          if (spi_send_done == 1'b1)            se_send_data <= se_addr[23:16];          else            se_send_data <= 8'd0;        end        M_ADDR      :   begin          if (spi_send_done == 1'b1)            se_send_data <= se_addr[15:8];          else            se_send_data <= 8'd0;        end        L_ADDR      :   begin          if (spi_send_done == 1'b1)            se_send_data <= se_addr[7:0];          else            se_send_data <= 8'd0;        end        SE_DONE     :   begin          se_send_data <= 8'd0;        end        default     :   se_send_data <= 8'd0;      endcase  end  always @ (posedge clk, negedge rst_n) begin    if (rst_n == 1'b0)      se_done <= 1'b0;    else      if (c_state == SE_DONE && spi_send_done == 1'b1)        se_done <= 1'b1;      else        se_done <= 1'b0;  endendmodule

在发送过程中，由于是每8bit发送一次，所以在时序上将看到发送时，每8个脉冲一组，中间会有明显的间隔。

pp设计实现

该模块负责将外部写fifo中的数据写入到flash中。wr_fifo_rd为写fifo的读使能信号，wrdata为从写fifo中读出的数据，wr_len为需要写入flash中数据的长度，wr_addr为写入地址。

该模块采用状态机实现。PP_STATE（发送pp命令），H_ADDR（发送高八位地址）、M_ADDR（发送中间八位地址），L_ADDR（发送低八位地址）、RDFIFO（读写fifo）、FIFO_WAIT（等待读写fifo的数据输出）、SEND（发送8bit数据）、SEND_WAIT（发送等待，发送完成后判断是否发送完成）。对于所有的脉冲信号，没有赋值的位置，全部赋值为0。

cnt为记录已经发送的数据个数。

设计代码为：

module pp (  input   wire                  clk,  input   wire                  rst_n,  input   wire                  pp_en,  output  reg                   pp_done,  output  reg                   wr_fifo_rd,  input   wire    [7:0]         wrdata,  input   wire    [8:0]         wr_len,  input   wire    [23:0]        wr_addr,  output  reg                   pp_send_en,  output  reg     [7:0]         pp_send_data,  input   wire                  spi_send_done);  localparam      PP_STATE    = 8'b0000_0001;  localparam      H_ADDR      = 8'b0000_0010;  localparam      M_ADDR      = 8'b0000_0100;  localparam      L_ADDR      = 8'b0000_1000;  localparam      RDFIFO      = 8'b0001_0000;  localparam      FIFO_WAIT   = 8'b0010_0000;  localparam      SEND        = 8'b0100_0000;  localparam      SEND_WAIT   = 8'b1000_0000;  reg             [7:0]         c_state;  reg             [7:0]         n_state;  reg             [8:0]         cnt;  always @ (posedge clk, negedge rst_n) begin    if (rst_n == 1'b0)      c_state <= PP_STATE;    else      c_state <= n_state;  end  always @ * begin    case (c_state)      PP_STATE        :   begin        if (pp_en == 1'b0)          n_state = PP_STATE;        else          n_state = H_ADDR;      end      H_ADDR          :   begin        if (spi_send_done == 1'b1)          n_state = M_ADDR;        else          n_state = H_ADDR;      end      M_ADDR          :   begin        if (spi_send_done == 1'b1)          n_state = L_ADDR;        else          n_state = M_ADDR;      end      L_ADDR          :   begin        if (spi_send_done == 1'b1)          n_state = RDFIFO;        else          n_state = L_ADDR;      end      RDFIFO          :   begin        if (spi_send_done == 1'b1)          n_state = FIFO_WAIT;        else          n_state = RDFIFO;      end      FIFO_WAIT       :   begin        n_state = SEND;      end      SEND            :   begin        n_state = SEND_WAIT;      end      SEND_WAIT       :   begin        if (spi_send_done == 1'b1)          if (cnt == wr_len)            n_state = PP_STATE;          else            n_state = FIFO_WAIT;        else          n_state = SEND_WAIT;      end      default       :   n_state = PP_STATE;    endcase  end  always @ (posedge clk, negedge rst_n) begin    if (rst_n == 1'b0)      pp_send_en <= 1'b0;    else      case (c_state)        PP_STATE      :   begin          if  (pp_en == 1'b1)            pp_send_en <= 1'b1;          else            pp_send_en <= 1'b0;        end        H_ADDR        :   begin          if (spi_send_done == 1'b1)            pp_send_en <= 1'b1;          else            pp_send_en <= 1'b0;        end        M_ADDR        :   begin          if (spi_send_done == 1'b1)            pp_send_en <= 1'b1;          else            pp_send_en <= 1'b0;        end        L_ADDR        :   begin          if (spi_send_done == 1'b1)            pp_send_en <= 1'b1;          else            pp_send_en <= 1'b0;        end        SEND          : begin          pp_send_en <= 1'b1;        end        default       :   pp_send_en <= 1'b0;      endcase  end  always @ (posedge clk, negedge rst_n) begin    if (rst_n == 1'b0)      pp_send_data <= 8'd0;    else      case (c_state)        PP_STATE      :   begin          if  (pp_en == 1'b1)            pp_send_data <= 8'h02;          else            pp_send_data <= 8'd0;        end        H_ADDR        :   begin          if (spi_send_done == 1'b1)            pp_send_data <= wr_addr[23:16];          else            pp_send_data <= 8'd0;        end        M_ADDR        :   begin          if (spi_send_done == 1'b1)            pp_send_data <= wr_addr[15:8];          else            pp_send_data <= 8'd0;        end        L_ADDR        :   begin          if (spi_send_done == 1'b1)            pp_send_data <= wr_addr[7:0];          else            pp_send_data <= 8'd0;        end        SEND          : begin          pp_send_data <= wrdata;        end        default       :   pp_send_data <= 8'd0;      endcase  end  always @ (posedge clk, negedge rst_n) begin    if (rst_n == 1'b0)      pp_done <= 1'b0;    else      if (c_state == SEND_WAIT && spi_send_done == 1'b1 && cnt == wr_len)        pp_done <= 1'b1;      else        pp_done <= 1'b0;  end  always @ (posedge clk, negedge rst_n) begin    if (rst_n == 1'b0)      cnt <= 9'd0;    else      if ((c_state == RDFIFO && spi_send_done == 1'b1) || (c_state == SEND_WAIT && spi_send_done == 1'b1 && cnt < wr_len))        cnt <= cnt + 1'b1;      else        if (c_state == PP_STATE)          cnt <= 9'd0;        else          cnt <= cnt;  end  always @ (posedge clk, negedge rst_n) begin    if (rst_n == 1'b0)      wr_fifo_rd <= 1'b1;    else      if ((c_state == RDFIFO && spi_send_done == 1'b1) || (c_state == SEND_WAIT && spi_send_done == 1'b1 && cnt < wr_len))        wr_fifo_rd <= 1'b1;      else        wr_fifo_rd <= 1'b0;  endendmodule

rdsr设计实现

本模块的功能为读取m25p16的状态寄存器，主要检测状态寄存器的最低位（WIP）。

WIP（write in progress ：正在进行写进程），该bie位表示了flash内部是否在进行写进程。如果处于写进程时，flash忽略外部所有的命令，所以建议在执行任何命令前，首先进行检测该位。1表示正在写进程中，0表示不处于写进程。

如果检测到正在写进程中，进行延迟1ms，然后再次读取该位状态。直到写进程结束。

本模块采用状态机设计实现。ILDE（发送读状态寄存器命令）、RDSRSTATE（发送读使能）、WIP（判断wip位）、 DELAY1ms（延迟1ms）。cnt为延迟1ms的计数器。

设计代码为：

module rdsr (  input   wire                    clk,  input   wire                    rst_n,  input   wire                    rdsr_en,  output  reg                     rdsr_done,  output  reg                     rdsr_send_en,  output  reg       [7:0]         rdsr_send_data,  input   wire                    spi_send_done,  output  reg                     rdsr_read_en,  input   wire      [7:0]         spi_read_data,  input   wire                    spi_read_done);  parameter     T_1ms           =       50_000;  localparam    IDLE            =       4'b0001;  localparam    RDSRSTATE       =       4'b0010;  localparam    WIP             =       4'b0100;  localparam    DELAY1ms        =       4'b1000;  reg               [3:0]         c_state;  reg               [3:0]         n_state;  reg               [15:0]        cnt;  always @ (posedge clk, negedge rst_n) begin    if (rst_n == 1'b0)      c_state <= IDLE;    else      c_state <= n_state;  end  always @ * begin    case (c_state)      IDLE          :   begin        if (rdsr_en == 1'b0)          n_state = IDLE;        else          n_state = RDSRSTATE;      end      RDSRSTATE     :   begin        if (spi_send_done == 1'b1)          n_state = WIP;        else          n_state = RDSRSTATE;      end      WIP           :   begin        if (spi_read_done == 1'b0)          n_state = WIP;        else          if (spi_read_data[0] == 1'b0)            n_state = IDLE;          else            n_state = DELAY1ms;      end      DELAY1ms      :   begin        if (cnt < T_1ms - 1'b1)          n_state = DELAY1ms;        else          n_state = RDSRSTATE;      end      default       :   n_state = IDLE;    endcase  end  always @ (posedge clk, negedge rst_n) begin    if (rst_n == 1'b0)      cnt <= 16'd0;    else      if (c_state == DELAY1ms && cnt < T_1ms - 1'b1)        cnt <= cnt + 1'b1;      else        cnt <= 16'd0;  end  always @ (posedge clk, negedge rst_n) begin    if (rst_n == 1'b0)      rdsr_done <= 1'b0;    else      if (c_state == WIP && spi_read_done == 1'b1 && spi_read_data[0] == 1'b0)        rdsr_done <= 1'b1;      else        rdsr_done <= 1'b0;  end  always @ (posedge clk, negedge rst_n) begin    if (rst_n == 1'b0)      rdsr_send_data <= 8'd0;    else      if ((c_state == IDLE && rdsr_en == 1'b1) || (c_state == DELAY1ms && cnt == T_1ms - 1'b1))        rdsr_send_data <= 8'h05;      else        rdsr_send_data <= 8'd0;  end  always @ (posedge clk, negedge rst_n) begin    if (rst_n == 1'b0)      rdsr_send_en <= 1'b0;    else      if ((c_state == IDLE && rdsr_en == 1'b1) || (c_state == DELAY1ms && cnt == T_1ms - 1'b1))        rdsr_send_en <= 1'b1;      else        rdsr_send_en <= 1'd0;  end  always @ (posedge clk, negedge rst_n) begin    if (rst_n == 1'b0)      rdsr_read_en <= 1'b0;    else      if (c_state == RDSRSTATE && spi_send_done == 1'b1)        rdsr_read_en <= 1'b1;      else        rdsr_read_en <= 1'b0;  endendmodule

rdid设计实现

该模块负责读取flash的ID（2015），验证ID的正确性。

该模块采用状态机的方式实现。IDLE（等待读取ID的命令）、IDSTATE1（读取高八位ID）、IDSTATE2（读取中间八位ID）、IDSTATE3（读取低八位ID）、ID_CHECK（检测ID的正确性）。

状态转移图如下：

设计代码为：

module rdid (  input     wire                  clk,  input     wire                  rst_n,  input     wire                  rdid_en,  output    reg                   rdid_done,  output    reg                   rdid_send_en,  output    reg     [7:0]         rdid_send_data,  input     wire                  spi_send_done,  output    reg                   rdid_read_en,  input     wire                  spi_read_done,  input     wire    [7:0]         spi_read_data);  localparam        IDLE          = 5'b00001;  localparam        IDSTATE1      = 5'b00010;  localparam        IDSTATE2      = 5'b00100;  localparam        IDSTATE3      = 5'b01000;  localparam        ID_CHECK      = 5'b10000;  reg               [4:0]         c_state;  reg               [4:0]         n_state;  always @ (posedge clk, negedge rst_n) begin    if (rst_n == 1'b0)      c_state <= IDLE;    else      c_state <= n_state;  end  always @ * begin    case (c_state)      IDLE          :     begin        if (rdid_en == 1'b1)          n_state = IDSTATE1;        else          n_state = IDLE;      end      IDSTATE1      :     begin        if (spi_send_done == 1'b1)          n_state = IDSTATE2;        else          n_state = IDSTATE1;      end      IDSTATE2      :     begin        if (spi_read_done == 1'b1 && spi_read_data == 8'h20)          n_state = IDSTATE3;        else          n_state = IDSTATE2;      end      IDSTATE3      :     begin        if (spi_read_done == 1'b1 && spi_read_data == 8'h20)          n_state = ID_CHECK;        else          n_state = IDSTATE3;      end      ID_CHECK      :     begin        if (spi_read_done == 1'b1 && spi_read_data == 8'h15)          n_state = IDLE;        else          n_state = ID_CHECK;      end      default       :   n_state = IDLE;    endcase  end  always @ (posedge clk, negedge rst_n) begin    if (rst_n == 1'b0)      rdid_send_data <= 8'd0;    else      if (c_state == IDLE && rdid_en == 1'b1)        rdid_send_data <= 8'h9f;      else        rdid_send_data <= 8'd0;  end  always @ (posedge clk, negedge rst_n) begin    if (rst_n == 1'b0)      rdid_send_en <= 1'b0;    else      if (c_state == IDLE && rdid_en == 1'b1)        rdid_send_en <= 1'b1;      else        rdid_send_en <= 1'b0;  end  always @ (posedge clk, negedge rst_n) begin    if (rst_n == 1'b0)      rdid_read_en <= 1'b0;    else      if ((c_state == IDSTATE1 && spi_send_done == 1'b1) || (c_state == IDSTATE2 && spi_read_done == 1'b1 && spi_read_data == 8'h20) || (c_state == IDSTATE3 && spi_read_done == 1'b1 && spi_read_data == 8'h20))        rdid_read_en <= 1'b1;      else        rdid_read_en <= 1'b0;  end  always @ (posedge clk, negedge rst_n) begin    if (rst_n == 1'b0)      rdid_done <= 1'b0;    else      if (c_state == ID_CHECK && spi_read_done == 1'b1 && spi_read_data == 8'h15)        rdid_done <= 1'b1;      else        rdid_done <= 1'b0;  endendmodule

read_ctrl设计实现

该模块负责将flash的数据读出，写入到输出缓存中。

该模块采用状态机实现。RD_STATE（等待读命令）、H_ADDR（发送高八位地址）、M_ADDR（发送中间八位地址）、L_ADDR（发送低八位地址）、RDDATA（读取数据）、WRFIFO（将读出的数据写入到FIFO中）、CHECK_LEN（判断读取的长度）。

状态转移图如下：

设计代码为：

module read_ctrl (  input     wire                clk,  input     wire                rst_n,  input     wire                read_en,  input     wire    [23:0]      rd_addr,  input     wire    [8:0]       rd_len,  output    reg     [7:0]       rddata,  output    reg                 rd_fifo_wr,  output    reg                 read_done,  output    reg                 read_send_en,  output    reg     [7:0]       read_send_data,  input     wire                spi_send_done,  output    reg                 read_read_en,  input     wire                spi_read_done,  input     wire    [7:0]       spi_read_data);  localparam        RD_STATE    = 7'b000_0001;  localparam        H_ADDR      = 7'b000_0010;  localparam        M_ADDR      = 7'b000_0100;  localparam        L_ADDR      = 7'b000_1000;  localparam        RDDATA      = 7'b001_0000;  localparam        WRFIFO      = 7'b010_0000;  localparam        CHECK_LEN   = 7'b100_0000;  reg               [6:0]       c_state;  reg               [6:0]       n_state;  reg               [8:0]       cnt;  always @ (posedge clk, negedge rst_n) begin    if (rst_n == 1'b0)      c_state <= RD_STATE;    else      c_state <= n_state;  end  always @ * begin    case (c_state)      RD_STATE      :   begin        if (read_en == 1'b1)          n_state = H_ADDR;        else          n_state = RD_STATE;      end      H_ADDR        :   begin        if (spi_send_done == 1'b1)          n_state = M_ADDR;        else          n_state = H_ADDR;      end      M_ADDR        :   begin        if (spi_send_done == 1'b1)          n_state = L_ADDR;        else          n_state = M_ADDR;      end      L_ADDR        :   begin        if (spi_send_done == 1'b1)          n_state = RDDATA;        else          n_state = L_ADDR;      end      RDDATA        :   begin        if (spi_send_done == 1'b1)          n_state = WRFIFO;        else          n_state = RDDATA;      end      WRFIFO        :   begin        if (spi_read_done == 1'b1)          n_state = CHECK_LEN;        else          n_state = WRFIFO;      end      CHECK_LEN     :   begin        if (cnt == rd_len)          n_state = RD_STATE;        else          n_state = WRFIFO;      end      default       :   n_state = RD_STATE;    endcase  end  always @ (posedge clk, negedge rst_n) begin    if (rst_n == 1'b0)      cnt <= 9'd0;    else      if ((c_state == RDDATA && spi_send_done == 1'b1) || (c_state == CHECK_LEN && cnt < rd_len))        cnt <= cnt + 1'b1;      else        if (c_state == RD_STATE)          cnt <= 9'd0;        else            cnt <= cnt;  end  always @ (posedge clk, negedge rst_n) begin    if (rst_n == 1'b0)      read_read_en <= 1'b0;    else      if ((c_state == RDDATA && spi_send_done == 1'b1) || (c_state == CHECK_LEN && cnt < rd_len))        read_read_en <= 1'b1;      else        read_read_en <= 1'b0;  end  always @ (posedge clk, negedge rst_n) begin    if (rst_n == 1'b0)      read_done <= 1'b0;    else      if (c_state == CHECK_LEN && cnt == rd_len)        read_done <= 1'b1;      else        read_done <= 1'b0;  end  always @ (posedge clk, negedge rst_n) begin    if (rst_n == 1'b0)      rd_fifo_wr <= 1'b0;    else      if (c_state == WRFIFO && spi_read_done == 1'b1)        rd_fifo_wr <= 1'b1;      else        rd_fifo_wr <= 1'b0;  end  always @ (posedge clk, negedge rst_n) begin    if (rst_n == 1'b0)      rddata <= 8'd0;    else      if (c_state == WRFIFO && spi_read_done == 1'b1)        rddata <= spi_read_data;      else        rddata <= 8'd0;  end  always @ (posedge clk, negedge rst_n) begin    if (rst_n == 1'b0)      read_send_en <= 1'b0;    else      case (c_state)        RD_STATE      :   begin          if  (read_en == 1'b1)            read_send_en <= 1'b1;          else            read_send_en <= 1'b0;        end        H_ADDR        :   begin          if (spi_send_done == 1'b1)            read_send_en <= 1'b1;          else            read_send_en <= 1'b0;        end        M_ADDR        :   begin          if (spi_send_done == 1'b1)            read_send_en <= 1'b1;          else            read_send_en <= 1'b0;        end        L_ADDR        :   begin          if (spi_send_done == 1'b1)            read_send_en <= 1'b1;          else            read_send_en <= 1'b0;        end        default       :   read_send_en <= 1'b0;      endcase  end  always @ (posedge clk, negedge rst_n) begin    if (rst_n == 1'b0)      read_send_data <= 8'd0;    else      case (c_state)        RD_STATE      :   begin          if  (read_en == 1'b1)            read_send_data <= 8'h03;          else            read_send_data <= 8'd0;        end        H_ADDR        :   begin          if (spi_send_done == 1'b1)            read_send_data <= rd_addr[23:16];          else            read_send_data <= 8'd0;        end        M_ADDR        :   begin          if (spi_send_done == 1'b1)            read_send_data <= rd_addr[15:8];          else            read_send_data <= 8'd0;        end        L_ADDR        :   begin          if (spi_send_done == 1'b1)            read_send_data <= rd_addr[7:0];          else            read_send_data <= 8'd0;        end        default       :   read_send_data <= 8'd0;      endcase  endendmodule

wr_fifo和rd_fifo调用

两个fifo的宽度设置为8，深度设置为256，同步fifo，带有复位。

ctrl设计实现

该模块根据外部的命令，按照m25p16的执行规则，进行控制各个模块的执行。

该模块采用状态机实现。INIT_RDSR（读WIP），INIT_RDID（读ID），INIT_ID（判断ID），WIP（读WIP），WIP_DONE（等待WIP），IDLE（空闲状态），**STATE（执行对应的命令），**WREN（打开flash的写使能）。在进行任何命令前，都检查wip。

状态转移图如下：

在不同的状态，mux_sel选择对应的命令通过。

drive_busy只有在IDLE状态才是低电平。

spi_cs_n信号， DLE状态为高电平、WIP_DONE（INIT_RDID）中spi_read_done信号为高时（保证能够多次读取状态寄存器）、在其他状态发生切换时，spi_cs_n 为高电平，否则为低电平。

设计代码为：

module ctrl (  input     wire                clk,  input     wire                rst_n,  input     wire                flag_be,  input     wire                flag_se,  input     wire                flag_wr,  input     wire                flag_rd,  input     wire    [23:0]      addr,  input     wire    [8:0]       len,  output    wire                drive_busy,  output    reg                 spi_cs_n,  input     wire                spi_read_done,  output    reg                 rdsr_en,  input     wire                rdsr_done,  output    reg                 wren_en,  input     wire                wren_done,  output    reg                 pp_en,  output    reg     [23:0]      wr_addr,  output    reg     [8:0]       wr_len,  input     wire                pp_done,  output    reg                 be_en,  input     wire                be_done,  output    reg                 se_en,  output    reg     [23:0]      se_addr,  input     wire                se_done,  output    reg                 rdid_en,  input     wire                rdid_done,  output    reg                 read_en,  output    reg     [23:0]      rd_addr,  output    reg     [8:0]       rd_len,  input     wire                read_done,  output    reg     [2:0]       mux_sel);  localparam        INIT_RDSR       =   13'b0000_0000_00001;  localparam        INIT_RDID       =   13'b0000_0000_00010;  localparam        INIT_ID         =   13'b0000_0000_00100;  localparam        WIP             =   13'b0000_0000_01000;  localparam        WIP_DONE        =   13'b0000_0000_10000;  localparam        IDLE            =   13'b0000_0001_00000;  localparam        RDSTATE         =   13'b0000_0010_00000;  localparam        PPWREN          =   13'b0000_0100_00000;  localparam        PPSTATE         =   13'b0000_1000_00000;  localparam        SEWREN          =   13'b0001_0000_00000;  localparam        SESTATE         =   13'b0010_0000_00000;  localparam        BEWREN          =   13'b0100_0000_00000;  localparam        BESTATE         =   13'b1000_0000_00000;  reg               [12:0]      c_state;  reg               [12:0]      n_state;  always @ (posedge clk, negedge rst_n) begin    if (rst_n == 1'b0)      c_state <= INIT_RDSR;    else      c_state <= n_state;  end  always @ * begin    case (c_state)      INIT_RDSR         :   begin        n_state = INIT_RDID;      end      INIT_RDID         :   begin        if (rdsr_done == 1'b1)          n_state = INIT_ID;        else          n_state = INIT_RDID;      end      INIT_ID           :   begin        if (rdid_done == 1'b1)          n_state = WIP;        else          n_state = INIT_ID;      end      WIP               :   begin        n_state = WIP_DONE;      end      WIP_DONE          :   begin        if (rdsr_done == 1'b1)          n_state = IDLE;        else          n_state = WIP_DONE;      end      IDLE              :   begin        if (flag_wr == 1'b1)          n_state = PPWREN;        else          if (flag_rd == 1'b1)            n_state = RDSTATE;          else            if (flag_be == 1'b1)              n_state = BEWREN;            else              if (flag_se == 1'b1)                n_state = SEWREN;              else                n_state = IDLE;      end      RDSTATE           :   begin        if (read_done == 1'b1)          n_state = WIP;        else          n_state = RDSTATE;      end      PPWREN            :   begin        if (wren_done == 1'b1)          n_state = PPSTATE;        else          n_state = PPWREN;      end      PPSTATE           :   begin        if (pp_done == 1'b1)          n_state = WIP;        else          n_state = PPSTATE;      end      SEWREN            :   begin        if (wren_done == 1'b1)          n_state = SESTATE;        else          n_state = SEWREN;      end      SESTATE           :   begin        if (se_done == 1'b1)          n_state = WIP;        else          n_state = SESTATE;      end      BEWREN            :   begin        if (wren_done == 1'b1)          n_state = BESTATE;        else          n_state = BEWREN;      end      BESTATE           :   begin        if (be_done == 1'b1)          n_state = WIP;        else          n_state = BESTATE;      end      default     :   n_state = INIT_RDSR;    endcase  end  assign drive_busy = (c_state != IDLE || flag_be == 1'b1 || flag_rd == 1'b1 || flag_se == 1'b1 || flag_wr == 1'b1);  always @ (posedge clk, negedge rst_n) begin    if (rst_n == 1'b0)      spi_cs_n <= 1'b1;    else      case (c_state)        INIT_RDSR       :     spi_cs_n <= 1'b1;        INIT_RDID       :     if (spi_read_done == 1'b1)                                spi_cs_n <= 1'b1;                              else                                spi_cs_n <= 1'b0;        INIT_ID         :     if (rdid_done == 1'b1)                                  spi_cs_n <= 1'b1;                              else                                spi_cs_n <= 1'b0;        WIP             :     spi_cs_n <= 1'b1;        WIP_DONE        :     if (spi_read_done == 1'b1)                                spi_cs_n <= 1'b1;                              else                                spi_cs_n <= 1'b0;        IDLE            :     spi_cs_n <= 1'b1;        RDSTATE         :     if (read_done == 1'b1)                                spi_cs_n <= 1'b1;                              else                                spi_cs_n <= 1'b0;        PPWREN          :     if (wren_done == 1'b1)                                spi_cs_n <= 1'b1;                              else                                spi_cs_n <= 1'b0;        PPSTATE         :     if (pp_done == 1'b1)                                spi_cs_n <= 1'b1;                              else                                spi_cs_n <= 1'b0;        SEWREN          :     if (wren_done == 1'b1)                                spi_cs_n <= 1'b1;                              else                                spi_cs_n <= 1'b0;        SESTATE         :     if (se_done == 1'b1)                                spi_cs_n <= 1'b1;                              else                                spi_cs_n <= 1'b0;        BEWREN          :     if (wren_done == 1'b1)                                spi_cs_n <= 1'b1;                              else                                spi_cs_n <= 1'b0;        BESTATE         :     if (be_done == 1'b1)                                spi_cs_n <= 1'b1;                              else                                spi_cs_n <= 1'b0;        default         :     spi_cs_n <= 1'b1;      endcase  end  always @ (posedge clk, negedge rst_n) begin    if (rst_n == 1'b0)      rdsr_en <= 1'b0;    else      if (c_state == INIT_RDSR || c_state == WIP)        rdsr_en <= 1'b1;      else        rdsr_en <= 1'b0;  end  always @ (posedge clk, negedge rst_n) begin    if (rst_n == 1'b0)      wren_en <= 1'b0;    else      if (c_state == IDLE && (flag_be == 1'b1 || flag_se == 1'b1 || flag_wr == 1'b1))        wren_en <= 1'b1;      else        wren_en <= 1'b0;  end  always @ (posedge clk, negedge rst_n) begin    if (rst_n == 1'b0)      pp_en <= 1'b0;    else      if (c_state == PPWREN && wren_done == 1'b1)        pp_en <= 1'b1;      else        pp_en <= 1'b0;  end  always @ (posedge clk, negedge rst_n) begin    if (rst_n == 1'b0)      wr_len <= 9'd0;    else      if (c_state == IDLE && flag_wr == 1'b1)        wr_len <= len;      else        wr_len <= wr_len;  end  always @ (posedge clk, negedge rst_n) begin    if (rst_n == 1'b0)      wr_addr <= 24'd0;    else      if (c_state == IDLE && flag_wr == 1'b1)        wr_addr <= addr;      else        wr_addr <= wr_addr;  end  always @ (posedge clk, negedge rst_n) begin    if (rst_n == 1'b0)      be_en <= 1'b0;    else      if (c_state == BEWREN && wren_done == 1'b1)        be_en <= 1'b1;      else        be_en <= 1'b0;  end  always @ (posedge clk, negedge rst_n) begin    if (rst_n == 1'b0)      se_en <= 1'b0;    else      if (c_state == SEWREN && wren_done == 1'b1)        se_en <= 1'b1;      else        se_en <= 1'b0;  end  always @ (posedge clk, negedge rst_n) begin    if (rst_n == 1'b0)      se_addr <= 24'd0;    else      if (c_state == IDLE && flag_se == 1'b1)        se_addr <= addr;      else        se_addr <= se_addr;  end  always @ (posedge clk, negedge rst_n) begin    if (rst_n == 1'b0)      rdid_en <= 1'b0;    else      if (c_state == INIT_RDID && rdsr_done == 1'b1)        rdid_en <= 1'b1;      else        rdid_en <= 1'b0;  end  always @ (posedge clk, negedge rst_n) begin    if (rst_n == 1'b0)      rd_len <= 9'd0;    else      if (c_state == IDLE && flag_rd == 1'b1)        rd_len <= len;      else        rd_len <= rd_len;  end  always @ (posedge clk, negedge rst_n) begin    if (rst_n == 1'b0)      rd_addr <= 24'd0;    else      if (c_state == IDLE && flag_rd == 1'b1)        rd_addr <= addr;      else        rd_addr <= rd_addr;  end  always @ (posedge clk, negedge rst_n) begin    if (rst_n == 1'b0)      read_en <= 1'b0;    else      if (c_state == IDLE && flag_rd == 1'b1)        read_en <= 1'b1;      else        read_en <= 1'b0;  end  always @ (posedge clk, negedge rst_n) begin    if (rst_n == 1'b0)      mux_sel <= 3'd0;    else      case (c_state)        INIT_RDSR       :   mux_sel <= 3'd0;        INIT_RDID       :   mux_sel <= 3'd0;        INIT_ID         :   mux_sel <= 3'd5;        WIP             :   mux_sel <= 3'd0;        WIP_DONE        :   mux_sel <= 3'd0;        IDLE            :   mux_sel <= 3'd0;        RDSTATE         :   mux_sel <= 3'd6;        PPWREN          :   mux_sel <= 3'd2;        PPSTATE         :   mux_sel <= 3'd1;        SEWREN          :   mux_sel <= 3'd2;        SESTATE         :   mux_sel <= 3'd4;        BEWREN          :   mux_sel <= 3'd2;        BESTATE         :   mux_sel <= 3'd3;        default         :   mux_sel <= 3'd0;      endcase  endendmodule

m25p16_drive设计实现

本模块负责连接所有二级模块，实现所有的功能。

module m25p16_drive (  input     wire                  clk,  input     wire                  rst_n,  input     wire                  wrfifo_wr,  input     wire    [7:0]         wrfifo_data,  input     wire                  flag_be,  input     wire                  flag_se,  input     wire                  flag_wr,  input     wire                  flag_rd,  input     wire    [23:0]        addr,  input     wire    [8:0]         len,  input     wire                  rdfifo_rd,  output    wire    [7:0]         rdfifo_rdata,  output    wire                  rdfifo_rdempty,  output    wire                  drive_busy,  output    wire                  spi_cs_n,  output    wire                  spi_sclk,  output    wire                  spi_mosi,  input     wire                  spi_miso);  wire                            spi_send_en;  wire              [7:0]         spi_send_data;  wire                            spi_send_done;  wire                            spi_read_en;  wire              [7:0]         spi_read_data;  wire                            spi_read_done;  wire                            rdsr_send_en;  wire              [7:0]         rdsr_send_data;  wire                            rdsr_read_en;  wire                            pp_send_en;  wire              [7:0]         pp_send_data;  wire                            wren_send_en;  wire              [7:0]         wren_send_data;  wire                            be_send_en;  wire              [7:0]         be_send_data;  wire                            se_send_en;  wire              [7:0]         se_send_data;  wire                            rdid_send_en;  wire              [7:0]         rdid_send_data;  wire                            rdid_read_en;  wire                            read_send_en;  wire              [7:0]         read_send_data;  wire                            read_read_en;  wire              [2:0]         mux_sel;  wire                            be_en;  wire                            be_done;  wire                            wren_en;  wire                            wren_done;  wire                            se_en;  wire              [23:0]        se_addr;  wire                            se_done;  wire                            pp_en;  wire                            pp_done;  wire                            wr_fifo_rd;  wire              [7:0]         wrdata;  wire              [8:0]         wr_len;  wire              [23:0]        wr_addr;  wire                            rdsr_en;  wire                            rdsr_done;  wire                            rdid_en;  wire                            rdid_done;  wire                            read_en;  wire              [23:0]        rd_addr;  wire              [8:0]         rd_len;  wire              [7:0]         rddata;  wire                            rd_fifo_wr;  wire                            read_done;  ctrl ctrl_inst(      .clk            (clk),      .rst_n          (rst_n),      .flag_be        (flag_be),      .flag_se        (flag_se),      .flag_wr        (flag_wr),      .flag_rd        (flag_rd),      .addr           (addr),      .len            (len),      .drive_busy     (drive_busy),      .spi_cs_n       (spi_cs_n),      .spi_read_done  (spi_read_done),      .rdsr_en        (rdsr_en),      .rdsr_done      (rdsr_done),      .wren_en        (wren_en),      .wren_done      (wren_done),      .pp_en          (pp_en),      .wr_addr        (wr_addr),      .wr_len         (wr_len),      .pp_done        (pp_done),      .be_en          (be_en),      .be_done        (be_done),      .se_en          (se_en),      .se_addr        (se_addr),      .se_done        (se_done),      .rdid_en        (rdid_en),      .rdid_done      (rdid_done),      .read_en        (read_en),      .rd_addr        (rd_addr),      .rd_len         (rd_len),      .read_done      (read_done),      .mux_sel        (mux_sel)    );  rd_fifo  rd_fifo_inst (      .aclr           ( ~rst_n ),      .clock          ( clk ),      .data           ( rddata ),      .rdreq          ( rdfifo_rd ),      .wrreq          ( rd_fifo_wr ),      .empty          ( rdfifo_rdempty ),      .q              ( rdfifo_rdata )    );  wr_fifo  wr_fifo_inst (      .aclr           ( ~rst_n ),      .clock          ( clk ),      .data           ( wrfifo_data ),      .rdreq          ( wr_fifo_rd ),      .wrreq          ( wrfifo_wr ),      .q              ( wrdata )    );  read_ctrl read_ctrl_inst(      .clk              (clk),      .rst_n            (rst_n),      .read_en          (read_en),      .rd_addr          (rd_addr),      .rd_len           (rd_len),      .rddata           (rddata),      .rd_fifo_wr       (rd_fifo_wr),      .read_done        (read_done),      .read_send_en     (read_send_en),      .read_send_data   (read_send_data),      .spi_send_done    (spi_send_done),      .read_read_en     (read_read_en),      .spi_read_done    (spi_read_done),      .spi_read_data    (spi_read_data)    );  rdid rdid_inst(      .clk              (clk),      .rst_n            (rst_n),      .rdid_en          (rdid_en),      .rdid_done        (rdid_done),      .rdid_send_en     (rdid_send_en),      .rdid_send_data   (rdid_send_data),      .spi_send_done    (spi_send_done),      .rdid_read_en     (rdid_read_en),      .spi_read_done    (spi_read_done),      .spi_read_data    (spi_read_data)    );  rdsr rdsr_inst(      .clk              (clk),      .rst_n            (rst_n),      .rdsr_en          (rdsr_en),      .rdsr_done        (rdsr_done),      .rdsr_send_en     (rdsr_send_en),      .rdsr_send_data   (rdsr_send_data),      .spi_send_done    (spi_send_done),      .rdsr_read_en     (rdsr_read_en),      .spi_read_data    (spi_read_data),      .spi_read_done    (spi_read_done)    );  pp pp_inst(      .clk              (clk),      .rst_n            (rst_n),      .pp_en            (pp_en),      .pp_done          (pp_done),      .wr_fifo_rd       (wr_fifo_rd),      .wrdata           (wrdata),      .wr_len           (wr_len),      .wr_addr          (wr_addr),      .pp_send_en       (pp_send_en),      .pp_send_data     (pp_send_data),      .spi_send_done    (spi_send_done)    );  se se_inst(      .clk              (clk),      .rst_n            (rst_n),      .se_en            (se_en),      .se_addr          (se_addr),      .se_done          (se_done),      .se_send_en       (se_send_en),      .se_send_data     (se_send_data),      .spi_send_done    (spi_send_done)    );  wren wren_inst(      .clk              (clk),      .rst_n            (rst_n),      .wren_en          (wren_en),      .wren_done        (wren_done),      .wren_send_en     (wren_send_en),      .wren_send_data   (wren_send_data),      .spi_send_done    (spi_send_done)    );  be be_inst(      .clk              (clk),      .rst_n            (rst_n),      .be_en            (be_en),      .be_done          (be_done),      .be_send_en       (be_send_en),      .be_send_data     (be_send_data),      .spi_send_done    (spi_send_done)    );  mux7_1 mux7_1_inst(      .rdsr_send_en     (rdsr_send_en),      .rdsr_send_data   (rdsr_send_data),      .rdsr_read_en     (rdsr_read_en),      .pp_send_en       (pp_send_en),      .pp_send_data     (pp_send_data),      .wren_send_en     (wren_send_en),      .wren_send_data   (wren_send_data),      .be_send_en       (be_send_en),      .be_send_data     (be_send_data),      .se_send_en       (se_send_en),      .se_send_data     (se_send_data),      .rdid_send_en     (rdid_send_en),      .rdid_send_data   (rdid_send_data),      .rdid_read_en     (rdid_read_en),      .read_send_en     (read_send_en),      .read_send_data   (read_send_data),      .read_read_en     (read_read_en),      .mux_sel          (mux_sel),      .spi_send_en      (spi_send_en),      .spi_send_data    (spi_send_data),      .spi_read_en      (spi_read_en)    );  spi_8bit_drive spi_8bit_drive_inst(      .clk              (clk),      .rst_n            (rst_n),      .spi_send_en      (spi_send_en),      .spi_send_data    (spi_send_data),      .spi_send_done    (spi_send_done),      .spi_read_en      (spi_read_en),      .spi_read_data    (spi_read_data),      .spi_read_done    (spi_read_done),      .spi_sclk         (spi_sclk),      .spi_mosi         (spi_mosi),      .spi_miso         (spi_miso)  );endmodule

RTL仿真

本次设计涉及到读取flash的id以及状态寄存器，所以在仿真时需要加入仿真模型。仿真模型放在msim的m25p16_sim_module中。m25p16为仿真模型的顶层文件。

由于读写和擦除的时间较长，RTL仿真中，将只仿真RDSR和RDID，其他的功能测试在板级测试时进行。

仿真代码如下：

`timescale 1ns/1psmodule m25p16_drive_tb;  reg             clk;  reg             rst_n;  wire            drive_busy;  wire            spi_cs_n;  wire            spi_sclk;  wire            spi_mosi;  wire            spi_miso;  m25p16_drive m25p16_drive_inst(      .clk              (clk),      .rst_n            (rst_n),      .wrfifo_wr        (1'b0),      .wrfifo_data      (8'd0),      .flag_be          (1'b0),      .flag_se          (1'b0),      .flag_wr          (1'b0),      .flag_rd          (1'b0),      .addr             (24'd0),      .len              (9'd0),      .rdfifo_rd        (1'b0),      .rdfifo_rdata     (),      .rdfifo_rdempty   (),      .drive_busy       (drive_busy),      .spi_cs_n         (spi_cs_n),      .spi_sclk         (spi_sclk),      .spi_mosi         (spi_mosi),      .spi_miso         (spi_miso)    );  m25p16 m25p16_inst(      .c                (spi_sclk),      .data_in          (spi_mosi),      .s                (spi_cs_n),      .w                (1'b1),      .hold             (1'b1),      .data_out         (spi_miso)    );  initial clk = 1'b0;  always # 50 clk = ~clk;  initial begin    rst_n = 1'b0;    # 201    rst_n = 1'b1;    @ (negedge drive_busy);    # 2000    $stop;  endendmodule

在设置testbench时，注意将所有文件全部添加到文件中。

选择testbench时，注意选中设置的m25p16_drive_tb。

利用modelsim仿真，可以得出如下RTL仿真波形。

读到ID，以及检测WIP都是正确的。

板级测试

由于m25p16的时序原因，整个设计工作在10MHz（利用PLL产生）。

在进行测试控制时，对最后一个扇区进行擦除；对最后一个扇区的第一页进行写入数据100个（1至100）；对最后一个扇区的第一个进行读取，验证数据是否为1至100。

测试的控制模块命名为test_ctrl。

此模块采用状态机实现。WRFIFO（将1至100写入wrfifo中）、SE（扇区擦除）、PP（写入flash）、RD（读出flash）、WAIT_RD（等待读取）、CHECK（检测读出的数据的正确性）。

设计代码为：

module test_ctrl (  input     wire                  clk,  input     wire                  rst_n,  output    reg                   wrfifo_wr,  output    reg     [7:0]         wrfifo_data,  output    reg                   flag_se,  output    reg                   flag_wr,  output    reg                   flag_rd,  input     wire                  drive_busy,  output    reg                   rdfifo_rd,  input     wire    [7:0]         rdfifo_rdata);  localparam      WRFIFO      =     6'b000_001;  localparam      SE          =     6'b000_010;  localparam      PP          =     6'b000_100;  localparam      RD          =     6'b001_000;  localparam      WAIT_RD     =     6'b010_000;  localparam      CHECK       =     6'b100_000;  reg               [5:0]         c_state;  reg               [5:0]         n_state;  always @ (posedge clk, negedge rst_n) begin    if (rst_n == 1'b0)      c_state <= WRFIFO;    else      c_state <= n_state;  end  always @ * begin    case (c_state)      WRFIFO        :   begin        if (wrfifo_data == 8'd100)          n_state = SE;        else          n_state = WRFIFO;      end      SE            :   begin        if (drive_busy == 1'b0)          n_state = PP;        else          n_state = SE;      end      PP            :   begin        if (drive_busy == 1'b0)          n_state = RD;        else          n_state = PP;      end      RD            :   begin        if (drive_busy == 1'b0)          n_state = WAIT_RD;        else          n_state = RD;      end      WAIT_RD       :   begin        if (drive_busy == 1'b0)          n_state = CHECK;        else          n_state = WAIT_RD;      end      CHECK         :   begin        n_state = CHECK;      end      default       :   n_state = WRFIFO;    endcase  end  always @ (posedge clk, negedge rst_n) begin    if (rst_n == 1'b0)      wrfifo_data <= 8'd0;    else      if (c_state == WRFIFO && wrfifo_data < 8'd100)        wrfifo_data <= wrfifo_data + 1'b1;      else        wrfifo_data <= 8'd0;  end  always @ (posedge clk, negedge rst_n) begin    if (rst_n == 1'b0)      wrfifo_wr <= 1'd0;    else      if (c_state == WRFIFO && wrfifo_data < 8'd100)        wrfifo_wr <= 1'd1;      else        wrfifo_wr <= 1'd0;  end  always @ (posedge clk, negedge rst_n) begin    if (rst_n == 1'b0)      flag_se <= 1'b0;    else      if (c_state == SE && drive_busy == 1'b0)        flag_se <= 1'b1;      else        flag_se <= 1'b0;  end  always @ (posedge clk, negedge rst_n) begin    if (rst_n == 1'b0)      flag_wr <= 1'b0;    else      if (c_state == PP && drive_busy == 1'b0)        flag_wr <= 1'b1;      else          flag_wr <= 1'b0;  end  always @ (posedge clk, negedge rst_n) begin    if (rst_n == 1'b0)      flag_rd <= 1'b0;    else      if (c_state == RD && drive_busy == 1'b0)        flag_rd <= 1'b1;      else        flag_rd <= 1'b0;  end  always @ (posedge clk, negedge rst_n) begin    if (rst_n == 1'b0)      rdfifo_rd <= 1'b0;    else      if (c_state == WAIT_RD && drive_busy == 1'b0)        rdfifo_rd <= 1'b1;      else        if (c_state == CHECK && rdfifo_rdata == 8'd99)          rdfifo_rd <= 1'b0;        else            rdfifo_rd <= rdfifo_rd;  endendmodule

将test模块设置为顶层。在test模块中，m25p16_drive例化中，对于整片擦除不做控制，对于addr直接指向最后一个扇区的第一页，len指定为100。

代码为：

module test (  input     wire                  clk,  input     wire                  rst_n,  output    wire                  spi_cs_n,  output    wire                  spi_sclk,  output    wire                  spi_mosi,  input     wire                  spi_miso);  wire                            wrfifo_wr;  wire              [7:0]         wrfifo_data;  wire                            flag_rd;  wire                            flag_se;  wire                            flag_wr;  wire                            drive_busy;  wire                            rdfifo_rd;  wire              [7:0]         rdfifo_rdata;  wire                            clk_10m;  wire                            pll_locked;  pll_test  pll_test_inst (      .areset             ( ~rst_n ),      .inclk0             ( clk ),      .c0                 ( clk_10m ),      .locked             ( pll_locked )    );  test_ctrl test_ctrl_inst(      .clk                (clk_10m),      .rst_n              (pll_locked),      .wrfifo_wr          (wrfifo_wr),      .wrfifo_data        (wrfifo_data),      .flag_se            (flag_se),      .flag_wr            (flag_wr),      .flag_rd            (flag_rd),      .drive_busy         (drive_busy),      .rdfifo_rd          (rdfifo_rd),      .rdfifo_rdata       (rdfifo_rdata)    );  m25p16_drive m25p16_drive_inst(      .clk              (clk_10m),      .rst_n            (pll_locked),      .wrfifo_wr        (wrfifo_wr),      .wrfifo_data      (wrfifo_data),      .flag_be          (1'b0),      .flag_se          (flag_se),      .flag_wr          (flag_wr),      .flag_rd          (flag_rd),      .addr             (24'hff0000),      .len              (9'd100),      .rdfifo_rd        (rdfifo_rd),      .rdfifo_rdata     (rdfifo_rdata),      .rdfifo_rdempty   (),      .drive_busy       (drive_busy),      .spi_cs_n         (spi_cs_n),      .spi_sclk         (spi_sclk),      .spi_mosi         (spi_mosi),      .spi_miso         (spi_miso)    );endmodule