用状态机实现通用多字节SPI接口模块

这次设计一个通用的多字节SPI接口模块，特点如下：

• 可以设置为1-128字节的SPI通信模块
• 可以修改CPOL、CPHA来进行不同的通信模式
• 可以设置输出的时钟
   
  状态转移图和思路与多字节串口发送模块一样，这里就不给出了，具体可看该随笔。

一、模块代码

1、需要的模块

通用8位SPI接口模块

`timescale 1ns / 1ps
//////////////////////////////////////////////////////////////////////////////////
// Company: 
// Engineer: Lclone
// 
// Create Date: 2023/01/23 00:56:52
// Design Name: SPI_Interface
// Module Name: SPI_Interface
// Project Name: 
// Target Devices: 
// Tool Versions: 
// Description: 
//      SPI接口模块
//      可修改分频参数来生成目标频率，最低分频系数为2；
//      可以置位CPOL、CPHA可以来设置通信模式；
//      本模块只有1位，但是可以简单修改位宽来设置多位片选信号
// Dependencies: 
// 
// Revision:
// Revision 0.01 - File Created
// Additional Comments:
// 
//////////////////////////////////////////////////////////////////////////////////


module SPI_Interface
#   (   
        parameter         Value_divide = 2)//分频系数（最低为2）
    (
        //-----------------内部接口------------------
        input              Clk,             //时钟
        input              Rst_n,           //复位信号
        input              CPOL,            //时钟极性
        input              CPHA,            //时钟相位
        input              CS_input,        //片选信号
        input              Send_en,         //发送使能
        input       [7:0]  Data_send,       //待发送数据
        output  reg        Read_en,        //接收数据读使能
        output  reg [7:0]  Data_recive,    //接收到的数据
        //------------------外部接口------------------
        output  reg        Spi_clk,        //输出时钟端
        output  reg        Spi_mosi,       //主输出从接收端
        input               Spi_miso,      //主接收从输出端
        output              Cs_output      //片选信号输出
    );

    reg         act_flag;                  //活动状态寄存器
    reg [9:0]   cnt_divide;                //分频计数器
    reg [7:0]   Data_send_reg;             //带发送数据寄存器
    reg [4:0]   cnt_pulse;                 //脉冲计数器
    
    
    always @(posedge Clk or negedge Rst_n) begin 
        if(Rst_n == 0)
            act_flag <= 0;
        else if(Send_en == 1)
            act_flag <= 1;
        else if(cnt_divide == Value_divide/2 - 1 & act_flag == 1 & cnt_pulse == 16)
            act_flag <= 0;
        else
            act_flag <= act_flag;
    end
    
    always @(posedge Clk or negedge Rst_n) begin
        if(Rst_n == 0)
            Read_en <= 0;
        else if(cnt_divide == Value_divide/2 - 1 & act_flag == 1 & cnt_pulse == 16)
            Read_en <= 1;
        else
            Read_en <= 0;
    end
    
    always @(posedge Clk or negedge Rst_n) begin
        if(Rst_n == 0)
            Data_send_reg <= 0;
        else if(Send_en == 1)
            Data_send_reg <= Data_send;
        else
            cnt_divide <= 0;
    end
    
    always @(posedge Clk or negedge Rst_n) begin 
        if(Rst_n == 0)
            cnt_divide <= 0;
        else if(cnt_divide == Value_divide/2 - 1 & act_flag == 1)
            cnt_divide <= 0;
        else if(act_flag == 1)
            cnt_divide <= cnt_divide + 1"b1;
        else
            cnt_divide <= 0;
    end
    

    always @(posedge Clk or negedge Rst_n) begin//生成目标时钟两倍频率的的cnt_pulse
        if(Rst_n == 0)
            cnt_pulse <= 0;
        else if(cnt_divide == Value_divide/2 - 1 & act_flag == 1 & cnt_pulse == 16)
            cnt_pulse <= 0;
        else if(cnt_divide == Value_divide/2 - 1 & act_flag == 1)
            cnt_pulse <= cnt_pulse + 1"b1;
        else if(act_flag == 1)
            cnt_pulse <= cnt_pulse;
        else
            cnt_pulse <= 0;
    end
    
    always @(posedge Clk or negedge Rst_n) begin
        if(Rst_n == 0)
            begin
                if(CPOL == 1)
                    begin
                        Spi_clk <= 1;
                        Spi_mosi <= 1;
                        Data_recive <= 0;
                    end
                else
                    begin
                        Spi_clk <= 0;
                        Spi_mosi <= 1;
                        Data_recive <= 0;
                    end
            end
        else if(cnt_divide == Value_divide/2 - 1 & act_flag == 1)
            begin
                if(CPHA == 0)
                    case(cnt_pulse)
                        0:begin  
                            Spi_clk <= Spi_clk;
                            Spi_mosi <= Data_send_reg[7];
                            Data_recive <= Data_recive;
                          end
                        1:begin
                            Spi_clk <= ~Spi_clk;
                            Spi_mosi <= Spi_mosi;
                            Data_recive[7] <= Spi_miso;
                          end
                        2:begin          
                            Spi_clk <= ~Spi_clk;            
                            Spi_mosi <= Data_send_reg[6];  
                            Data_recive <= Data_recive;    
                          end            
                        3:begin          
                            Spi_clk <= ~Spi_clk;         
                            Spi_mosi <= Spi_mosi;        
                            Data_recive[6] <= Spi_miso;  
                          end            
                        4:begin          
                            Spi_clk <= ~Spi_clk;            
                            Spi_mosi <= Data_send_reg[5];  
                            Data_recive <= Data_recive;    
                          end            
                        5:begin          
                            Spi_clk <= ~Spi_clk;         
                            Spi_mosi <= Spi_mosi;        
                            Data_recive[5] <= Spi_miso;  
                          end            
                        6:begin          
                            Spi_clk <= ~Spi_clk;            
                            Spi_mosi <= Data_send_reg[4];  
                            Data_recive <= Data_recive;    
                          end            
                        7:begin          
                            Spi_clk <= ~Spi_clk;         
                            Spi_mosi <= Spi_mosi;        
                            Data_recive[4] <= Spi_miso;  
                          end            
                        8:begin          
                            Spi_clk <= ~Spi_clk;            
                            Spi_mosi <= Data_send_reg[3];  
                            Data_recive <= Data_recive;    
                          end            
                        9:begin          
                            Spi_clk <= ~Spi_clk;         
                            Spi_mosi <= Spi_mosi;        
                            Data_recive[3] <= Spi_miso;  
                          end            
                        10:begin          
                            Spi_clk <= ~Spi_clk;           
                            Spi_mosi <= Data_send_reg[2]; 
                            Data_recive <= Data_recive;   
                          end            
                        11:begin          
                            Spi_clk <= ~Spi_clk;         
                            Spi_mosi <= Spi_mosi;        
                            Data_recive[2] <= Spi_miso;  
                          end            
                        12:begin          
                            Spi_clk <= ~Spi_clk;            
                            Spi_mosi <= Data_send_reg[1];  
                            Data_recive <= Data_recive;    
                          end            
                        13:begin          
                            Spi_clk <= ~Spi_clk;         
                            Spi_mosi <= Spi_mosi;        
                            Data_recive[1] <= Spi_miso;  
                          end            
                        14:begin          
                            Spi_clk <= ~Spi_clk;            
                            Spi_mosi <= Data_send_reg[0];  
                            Data_recive <= Data_recive;    
                          end            
                        15:begin          
                            Spi_clk <= ~Spi_clk;         
                            Spi_mosi <= Spi_mosi;        
                            Data_recive[0] <= Spi_miso;  
                          end
                        16:begin
                            Spi_clk <= ~Spi_clk;       
                            Spi_mosi <= 1;      
                            Data_recive <= Data_recive;
                         end
                        default:;
                    endcase
                else
                    case(cnt_pulse)
                        0:begin  
                            Spi_clk <= ~Spi_clk;
                            Spi_mosi <= Data_send_reg[7];
                            Data_recive <= Data_recive;
                          end
                        1:begin
                            Spi_clk <= ~Spi_clk;
                            Spi_mosi <= Spi_mosi;
                            Data_recive[7] <= Spi_miso;
                          end
                        2:begin          
                            Spi_clk <= ~Spi_clk;         
                            Spi_mosi <= Data_send_reg[6];
                            Data_recive <= Data_recive;  
                          end            
                        3:begin
                            Spi_clk <= ~Spi_clk;       
                            Spi_mosi <= Spi_mosi;      
                            Data_recive[6] <= Spi_miso;
                          end            
                        4:begin          
                            Spi_clk <= ~Spi_clk;         
                            Spi_mosi <= Data_send_reg[5];
                            Data_recive <= Data_recive;  
                          end            
                        5:begin          
                            Spi_clk <= ~Spi_clk;       
                            Spi_mosi <= Spi_mosi;      
                            Data_recive[5] <= Spi_miso;
                          end            
                        6:begin          
                            Spi_clk <= ~Spi_clk;           
                            Spi_mosi <= Data_send_reg[4];  
                            Data_recive <= Data_recive;    
                          end            
                        7:begin          
                            Spi_clk <= ~Spi_clk;         
                            Spi_mosi <= Spi_mosi;        
                            Data_recive[4] <= Spi_miso;  
                          end            
                        8:begin          
                            Spi_clk <= ~Spi_clk;         
                            Spi_mosi <= Data_send_reg[3];
                            Data_recive <= Data_recive;  
                          end            
                        9:begin          
                            Spi_clk <= ~Spi_clk;         
                            Spi_mosi <= Spi_mosi;        
                            Data_recive[3] <= Spi_miso; 
                          end            
                        10:begin          
                            Spi_clk <= ~Spi_clk;         
                            Spi_mosi <= Data_send_reg[2];
                            Data_recive <= Data_recive;  
                          end            
                        11:begin          
                            Spi_clk <= ~Spi_clk;       
                            Spi_mosi <= Spi_mosi;      
                            Data_recive[2] <= Spi_miso;
                          end            
                        12:begin          
                            Spi_clk <= ~Spi_clk;         
                            Spi_mosi <= Data_send_reg[1];
                            Data_recive <= Data_recive;  
                          end            
                        13:begin          
                            Spi_clk <= ~Spi_clk;       
                            Spi_mosi <= Spi_mosi;      
                            Data_recive[1] <= Spi_miso;
                          end            
                        14:begin          
                            Spi_clk <= ~Spi_clk;         
                            Spi_mosi <= Data_send_reg[0];
                            Data_recive <= Data_recive;  
                          end            
                        15:begin          
                            Spi_clk <= ~Spi_clk;       
                            Spi_mosi <= Spi_mosi;      
                            Data_recive[0] <= Spi_miso;
                          end
                        16:begin                       
                            Spi_clk <= Spi_clk;       
                            Spi_mosi <= 1;      
                            Data_recive <= Data_recive;
                          end                          
                        default:;
                    endcase        
            end
    end
    
    assign Cs_output = CS_input;
    
endmodule

2、设计的模块

`timescale 1ns / 1ps
//////////////////////////////////////////////////////////////////////////////////
// Company: GDUT
// Engineer: Lclone
// 
// Create Date: 2023/01/23 22:12:11
// Design Name: SPI_Bytes
// Module Name: SPI_Bytes
// Project Name: 
// Target Devices: 
// Tool Versions: 
// Description: 
//              - 可以设置位1-128字节的SPI通信模块
//              - 可以修改CPOL、CPHA来进行不同的通信模式
//              - 可以设置输出的时钟
// 
// Dependencies: 
// 
// Revision:
// Revision 0.01 - File Created
// Additional Comments:
// 
//////////////////////////////////////////////////////////////////////////////////


module SPI_Bytes
#   (
        parameter                    Data_Width = 16,       //数据位宽
        parameter                    ROUNDS = Data_Width/8) //传输轮数（例化时不需要设置）
    (
        //-----------------内部接口--------------------
        input                         Clk,                    //时钟信号
        input                         Rst_n,                  //复位信号
        input        [Data_Width-1:0] Send_Bytes_Data,        //发送的多字节数据
        input                         Bytes_Send_en,          //多字节发送使能
        output reg   [Data_Width-1:0] Recive_Bytes_Data,      //接收的多字节数据
        output reg                    Bytes_Read_en,          //多字节读使能
        input                         Cs_input,               //片选信号输入
        //-----------------外部接口--------------------
        output                        Spi_mosi,               //主输出从输入
        input                         Spi_miso,               //主输入从输出
        output                        Spi_clk,                //输出时钟
        output                        Cs_output               //片选信号输出
    );
    
    reg                  send_en;                             //发送使能
    wire                 read_en;                             //读使能
    reg [7:0]            data_send;                           //待发送数据
    reg [Data_Width-1:0] Send_Bytes_Data_reg;                 //多字节数据寄存器
    wire[7:0]            data_recive;                         //接收的数据
    reg [9:0]            round;                               //发送次数（修改该位宽可改变最大发送数据位宽）
    reg [1:0]            state;                               //状态寄存器
    
    always @(posedge Clk or negedge Rst_n) begin
        if(Rst_n == 0)
            round <= 0;
        else if(round == ROUNDS)
            round <= 0;
        else if(read_en == 1)
            round <= round + 1"b1;
        else
            round <= round;
    end
    
    always @(posedge Clk or negedge Rst_n) begin//状态机
        if(Rst_n == 0)
            begin
                state <= 0;
                Bytes_Read_en <= 0;
                data_send <= 0;
                Send_Bytes_Data_reg <= 0;
                send_en <= 0;
                Recive_Bytes_Data <= 0;
            end
        else case(state)
            0://空闲状态
                begin
                    Bytes_Read_en <= 0;
                    if(Bytes_Send_en == 1)
                        begin
                            state <= 1;
                            Send_Bytes_Data_reg <= Send_Bytes_Data;
                        end
                    else 
                        state <= 0;
                end
            1://发送状态
                begin
                    send_en <= 0;
                    if(round == ROUNDS)
                        begin
                            state <= 0;
                            Bytes_Read_en <= 1;
                            Recive_Bytes_Data[7:0] <= data_recive;//由于发送和接收的时序略有不同，这里给接收做个补偿。
                        end
                     else
                        begin
                            state <= 2;
                            send_en <= 1;
                            data_send <= Send_Bytes_Data_reg[Data_Width-1:Data_Width-8];//发送高位
                            Recive_Bytes_Data[7:0] <= data_recive;//把接收到的数据放在低位
                        end
                end
            2://数据移位
                begin
                    send_en <= 0;
                    if(read_en == 1)
                        begin
                            Send_Bytes_Data_reg <= Send_Bytes_Data_reg << 8;//高位刷新
                            Recive_Bytes_Data <= Recive_Bytes_Data << 8;//把低位的数据移到高位
                            state <= 1;
                        end
                    else
                        state <= 2;
                end
            default:;
        endcase
    end
SPI_Interface
#   (   
        .Value_divide                   (4))            //分频系数
SPI_SPI_Interface_inst
    (
        //-----------------内部接口------------------
        .Clk                            (Clk),          //时钟信号
        .Rst_n                          (Rst_n),        //复位信号
        .CPOL                           (1),
        .CPHA                           (0),
        .CS_input                       (1),            //片选输入
        .Send_en                        (send_en),      //发送使能
        .Data_send                      (data_send),    //待发送数据
        .Read_en                        (read_en),      //读使能
        .Data_recive                    (data_recive),  //接收的数据
        //------------------外部接口------------------
        .Spi_clk                        (Spi_clk),      //输出时钟
        .Spi_mosi                       (Spi_mosi),     //主输出从输入
        .Spi_miso                       (Spi_miso),     //主输入从输出
        .Cs_output                      (Cs_output)     //片选输出
    );
endmodule

二、仿真

1、仿真激励

`timescale 1ns / 1ps
//////////////////////////////////////////////////////////////////////////////////
// Company: 
// Engineer: 
// 
// Create Date: 2023/01/26 16:00:48
// Design Name: 
// Module Name: SPI_Bytes_tb
// Project Name: 
// Target Devices: 
// Tool Versions: 
// Description: 
// 
// Dependencies: 
// 
// Revision:
// Revision 0.01 - File Created
// Additional Comments:
// 
//////////////////////////////////////////////////////////////////////////////////


module SPI_Bytes_tb();
 
reg clk_50m;
initial clk_50m <= 1;
always #10 clk_50m <= ~clk_50m;
 
reg rst_n;
initial begin
    rst_n <= 0;
    #200
    rst_n <= 1;
end
 
reg             Bytes_Send_en;
reg     [31:0]  Send_Bytes_Data;
wire            Bytes_Read_en;
wire    [31:0]  Recive_Bytes_Data;
wire            Spi_clk;
wire            Spi_mosi;
wire            Spi_miso;
wire            Cs_output;
 
SPI_Bytes
#   (
        .Data_Width                   (32))//数据位宽为32位
SPI_Bytes_inst
    (
        //-----------------内部接口--------------------
        .Clk                            (clk_50m),
        .Rst_n                          (rst_n),
        .Send_Bytes_Data                (Send_Bytes_Data),
        .Bytes_Send_en                  (Bytes_Send_en),
        .Recive_Bytes_Data              (Recive_Bytes_Data),
        .Bytes_Read_en                  (Bytes_Read_en),
        .Cs_input                       (1"b1),
        //-----------------外部接口--------------------
        .Spi_mosi                       (Spi_mosi),
        .Spi_miso                       (Spi_miso),
        .Spi_clk                        (Spi_clk),
        .Cs_output                      (Cs_output)
    );
 
assign Spi_miso = Spi_mosi;
 
initial begin
    Bytes_Send_en <= 0;
    Send_Bytes_Data <= 0;
    #400;
    Bytes_Send_en <= 1;
    Send_Bytes_Data <= 32"h89abcdef;
    #20
    Bytes_Send_en <= 0;
    #4000;
    Bytes_Send_en <= 1;
    Send_Bytes_Data <= 32"h12345678;
    #20
    Bytes_Send_en <= 0;
end
 
endmodule

2、仿真结果

仿真结果：两次多字节发送都能正确的发送和接收数据，且能正确的生成Bytes_Read_en信号。模块仿真验证可行。