Chapter007-FPGA学习之IIC总线EEPROM读取

IIC总线是嵌入式领域较为重要的器件间通信总线,同样,FPGA也能通过模块的形式实现IIC的功能,其原理和STM32的模拟IIC总线一致,就是控制每个时间点的SCL、SDA总线电平。
IIC总线需要对应的从机机通信器件进行通信,故目前使用AT24C64【IIC总线的EEPROM】作为从机,通过实现对EEPROM的读、写,来学习IIC协议在FPGA的实现。

硬件原理

由于IIC本质就是2线通信方式,以从机地址作为鉴别依据,在IIC总线上进行点对点通信,故不再对细节的硬件进行描述,使用拓扑图即可说明问题,再IIC总线上,EEPROM的从机地址为7‘h50,也就是二进制的0b1010000。
Chapter007-FPGA学习之IIC总线EEPROM读取_第1张图片
IIC总线的通信波形图我就不过多赘述,大致电文思路就是:
开始–>器件地址输出–>读写功能输出–>等待反馈–>数据地址(读/写)–>等待反馈–>数据与内容(读/写)–>等待反馈–>结束

相关线路的引脚如下:
Chapter007-FPGA学习之IIC总线EEPROM读取_第2张图片
时序分为写时序、读时序,具体内容如下:
写时序:
Chapter007-FPGA学习之IIC总线EEPROM读取_第3张图片
连续写就是将8bit的数据与往后继续发送;

读时序:
Chapter007-FPGA学习之IIC总线EEPROM读取_第4张图片
若要实现连续读,将最后一个主机非应答变为主机应答即可,需要读几个就应答几次。

设计目标

设计目标为将EEPROM中,地址从0开始到255顺序写入0 ~ 255的数值,写入完成后,将地址0 ~ 255的数据读取出来,并检查是否地址与数据相对应,若数据与地址完全一致,则使红色PL_LED闪烁、否则PL_LED常亮。

使用到的资源为:
1、IIC的SCL线和SDA线
2、用于指示的LED灯
3、复位和系统时钟

模块分析
由于需要使用到EEPROM外设,而外设使用IIC总线进行通信,故首先需要实现IIC总线驱动模块
输入:
位控制信号【数据地址可能位0 ~ 255(8bit)或0 ~ 65535(16bit)】
系统时钟
IIC的数据地址
IIC需要写入的数据【8bit】
IIC使能信号
IIC读写控制信号
模块复位信号

输出:
上层模块的控制时钟【用于让上层模块使用匹配的频率向该模块发送数据】
IIC是否收到应答的标志
IIC读取到的数据【8bit】
IIC当前操作完成标志
IIC总线的SCL信号
IIC总线的SDA信号

当有了IIC的驱动模块后,上层的功能只需要将对应的地址、数据按一定的节拍发送给IIC驱动模块,即可实现IIC的通信,故需要实现EEPROM的读写给,需要有一个读写流程的逻辑模块实现这一功能;
输入:
IIC操作时钟
IIC是否收到应答的标志
IIC读取到的数据【8bit】
IIC当前操作完成标记
复位

输出:
需要操作的IIC地址
IIC写入的数据
IIC驱动模块的使能信号
IIC的读写标记
读写完成标记【用于驱动LED模块】
读写结果【用于驱动LED模块】

最后就是之前提到的用于描述实验是否成功的LED模块,若写入和读取内容一致,则LED闪烁,若不一致则LED长亮;
输入:
运行时钟
复位
读写完成标记
读写结果

输出:
LED灯控制信号

之后使用上层模块将上述子模块例化,即可得到整体设计;
输入:
系统时钟
复位
输出:
IIC_CLK
IIC_SDA
LED

模块原理图如下所示:
Chapter007-FPGA学习之IIC总线EEPROM读取_第5张图片

代码编辑

Verilog语言的代码包括以下几个部分:
一个用于例化子模块的顶层模块;

  1. IIC驱动模块【i2c_driver.v】
  2. EEPROM读写控制模块【eeprom_rw.v】
  3. led报警模块【led_alarm.v】

顶层模块相关代码

顶层模块代码(eeprom_top.v):

`timescale 1ns / 1ps
//
// Company: 
// Engineer: 
// 
// Create Date: 2022/07/21 21:29:06
// Design Name: 
// Module Name: eeprom_top
// Project Name: 
// Target Devices: 
// Tool Versions: 
// Description: 
// 
// Dependencies: 
// 
// Revision:
// Revision 0.01 - File Created
// Additional Comments:
// 
//


module eeprom_top(
    input               sys_clk    ,      //系统时钟
    input               sys_rst_n  ,      //系统复位
    //eeprom interface
    output              iic_scl    ,      //eeprom的时钟线scl
    inout               iic_sda    ,      //eeprom的数据线sda
    //user interface
    output              led               //led显示
    );
 
//parameter define
parameter    SLAVE_ADDR = 7'b1010000     ; //器件地址(SLAVE_ADDR)
parameter    BIT_CTRL   = 1'b1           ; //字地址位控制参数(16b/8b)
parameter    CLK_FREQ   = 26'd50_000_000 ; //i2c_dri模块的驱动时钟频率(CLK_FREQ)
parameter    I2C_FREQ   = 18'd250_000    ; //I2C的SCL时钟频率
parameter    L_TIME     = 17'd125_000    ; //led闪烁时间参数

//wire define
wire           dri_clk   ; //I2C操作时钟
wire           i2c_exec  ; //I2C触发控制
wire   [15:0]  i2c_addr  ; //I2C操作地址
wire   [ 7:0]  i2c_data_w; //I2C写入的数据
wire           i2c_done  ; //I2C操作结束标志
wire           i2c_ack   ; //I2C应答标志 0:应答 1:未应答
wire           i2c_rh_wl ; //I2C读写控制
wire   [ 7:0]  i2c_data_r; //I2C读出的数据
wire           rw_done   ; //E2PROM读写测试完成
wire           rw_result ; //E2PROM读写测试结果 0:失败 1:成功 

//*****************************************************
//**                    main code
//*****************************************************   
//e2prom读写测试模块
eeprom_rw u_eeprom_rw(
    .clk         (dri_clk   ),  //时钟信号
    .rst_n       (sys_rst_n ),  //复位信号
    //i2c interface
    .i2c_exec    (i2c_exec  ),  //I2C触发执行信号
    .i2c_rh_wl   (i2c_rh_wl ),  //I2C读写控制信号
    .i2c_addr    (i2c_addr  ),  //I2C器件内地址
    .i2c_data_w  (i2c_data_w),  //I2C要写的数据
    .i2c_data_r  (i2c_data_r),  //I2C读出的数据
    .i2c_done    (i2c_done  ),  //I2C一次操作完成
    .i2c_ack     (i2c_ack   ),  //I2C应答标志 
    //user interface
    .rw_done     (rw_done   ),  //E2PROM读写测试完成
    .rw_result   (rw_result )   //E2PROM读写测试结果 0:失败 1:成功
);

//i2c驱动模块
i2c_driver #(
    .SLAVE_ADDR  (SLAVE_ADDR),  //EEPROM从机地址
    .CLK_FREQ    (CLK_FREQ  ),  //模块输入的时钟频率
    .I2C_FREQ    (I2C_FREQ  )   //IIC_SCL的时钟频率
) u_i2c_driver(
    .clk         (sys_clk   ),  
    .rst_n       (sys_rst_n ),  
    //i2c interface
    .i2c_exec    (i2c_exec  ),  //I2C触发执行信号
    .bit_ctrl    (BIT_CTRL  ),  //器件地址位控制(16b/8b)
    .i2c_rh_wl   (i2c_rh_wl ),  //I2C读写控制信号
    .i2c_addr    (i2c_addr  ),  //I2C器件内地址
    .i2c_data_w  (i2c_data_w),  //I2C要写的数据
    .i2c_data_r  (i2c_data_r),  //I2C读出的数据
    .i2c_done    (i2c_done  ),  //I2C一次操作完成
    .i2c_ack     (i2c_ack   ),  //I2C应答标志
    .scl         (iic_scl   ),  //I2C的SCL时钟信号
    .sda         (iic_sda   ),  //I2C的SDA信号
    //user interface
    .dri_clk     (dri_clk   )   //I2C操作时钟
);

//led指示模块
led_alarm #(.L_TIME(L_TIME  )   //控制led闪烁时间
) u_led_alarm(
    .clk         (dri_clk   ),  
    .rst_n       (sys_rst_n ), 
    
    .rw_done     (rw_done   ),  
    .rw_result   (rw_result ),
    .led         (led       )    
);    
    
endmodule

顶层约束文件(eeprom_top.xdc):

set_property -dict {PACKAGE_PIN U18 IOSTANDARD LVCMOS33} [get_ports sys_clk]
set_property -dict {PACKAGE_PIN N16 IOSTANDARD LVCMOS33} [get_ports sys_rst_n]
set_property -dict {PACKAGE_PIN E18 IOSTANDARD LVCMOS33} [get_ports iic_scl]
set_property -dict {PACKAGE_PIN F17 IOSTANDARD LVCMOS33} [get_ports iic_sda]
set_property -dict {PACKAGE_PIN H15 IOSTANDARD LVCMOS33} [get_ports led]

下层功能模块代码

IIC驱动模块,负责将数据与地址操作变为IIC上的电平信号【i2c_driver.v】
该模块将IIC总线输出信号使用复杂的三段式状态机表述【同步时序表述状态转移、组合逻辑判断状态转移、各状态下正常功能执行】,具体含义可见代码注释表述;

`timescale 1ns / 1ps
//
// Company: 
// Engineer: 
// 
// Create Date: 2022/07/21 21:36:55
// Design Name: 
// Module Name: i2c_driver
// Project Name: 
// Target Devices: 
// Tool Versions: 
// Description: 
// 
// Dependencies: 
// 
// Revision:
// Revision 0.01 - File Created
// Additional Comments:
// 
//


module i2c_driver
    #(
      parameter   SLAVE_ADDR = 7'b1010000   ,  //EEPROM从机地址
      parameter   CLK_FREQ   = 26'd50_000_000, //模块输入的时钟频率
      parameter   I2C_FREQ   = 18'd250_000     //IIC_SCL的时钟频率
    )
    (
    input                clk        ,    
    input                rst_n      ,   
                                         
    //i2c interface                      
    input                i2c_exec   ,  //I2C触发执行信号
    input                bit_ctrl   ,  //字地址位控制(16b/8b)
    input                i2c_rh_wl  ,  //I2C读写控制信号
    input        [15:0]  i2c_addr   ,  //I2C器件内地址
    input        [ 7:0]  i2c_data_w ,  //I2C要写的数据
    output  reg  [ 7:0]  i2c_data_r ,  //I2C读出的数据
    output  reg          i2c_done   ,  //I2C一次操作完成
    output  reg          i2c_ack    ,  //I2C应答标志 0:应答 1:未应答
    output  reg          scl        ,  //I2C的SCL时钟信号
    inout                sda        ,  //I2C的SDA信号
                                       
    //user interface                   
    output  reg          dri_clk       //驱动I2C操作的驱动时钟
    );
    
//localparam define
localparam  st_idle     = 8'b0000_0001; //空闲状态
localparam  st_sladdr   = 8'b0000_0010; //发送器件地址(slave address)
localparam  st_addr16   = 8'b0000_0100; //发送16位字地址
localparam  st_addr8    = 8'b0000_1000; //发送8位字地址
localparam  st_data_wr  = 8'b0001_0000; //写数据(8 bit)
localparam  st_addr_rd  = 8'b0010_0000; //发送器件地址读
localparam  st_data_rd  = 8'b0100_0000; //读数据(8 bit)
localparam  st_stop     = 8'b1000_0000; //结束I2C操作

//reg define
reg            sda_dir   ; //I2C数据(SDA)方向控制
reg            sda_out   ; //SDA输出信号
reg            st_done   ; //状态结束
reg            wr_flag   ; //写标志
reg    [ 6:0]  cnt       ; //计数
reg    [ 7:0]  cur_state ; //状态机当前状态
reg    [ 7:0]  next_state; //状态机下一状态
reg    [15:0]  addr_t    ; //地址
reg    [ 7:0]  data_r    ; //读取的数据
reg    [ 7:0]  data_wr_t ; //I2C需写的数据的临时寄存
reg    [ 9:0]  clk_cnt   ; //分频时钟计数

//wire define
wire          sda_in     ; //SDA输入信号
wire   [8:0]  clk_divide ; //模块驱动时钟的分频系数

//*****************************************************
//**                    main code
//*****************************************************

//SDA控制
assign  sda        = sda_dir ?  sda_out : 1'bz   ;  //SDA数据输出或高阻
assign  sda_in     = sda                         ;  //SDA数据输入
assign  clk_divide = (CLK_FREQ/I2C_FREQ) >> 2'd2 ;  //模块驱动时钟的分频系数

//生成I2C的SCL的四倍频率的驱动时钟用于驱动i2c的操作
always @(posedge clk or negedge rst_n) begin
    if(!rst_n) begin
        dri_clk <=  1'b0;
        clk_cnt <= 10'd0;
    end
    else if(clk_cnt == clk_divide[8:1] - 1'd1) begin
        clk_cnt <= 10'd0;
        dri_clk <= ~dri_clk;
    end
    else
        clk_cnt <= clk_cnt + 1'b1;
end

//(三段式状态机)同步时序描述状态转移
always @(posedge dri_clk or negedge rst_n) begin
    if(!rst_n)
        cur_state <= st_idle;
    else
        cur_state <= next_state;
end

//组合逻辑判断状态转移条件
always @(*) begin
    next_state = st_idle;
    case(cur_state)
        st_idle: begin                          //空闲状态
           if(i2c_exec) begin
               next_state = st_sladdr;
           end
           else
               next_state = st_idle;
        end
        st_sladdr: begin
            if(st_done) begin
                if(bit_ctrl)                    //判断是16位还是8位字地址
                   next_state = st_addr16;
                else
                   next_state = st_addr8 ;
            end
            else
                next_state = st_sladdr;
        end
        st_addr16: begin                        //写16位字地址
            if(st_done) begin
                next_state = st_addr8;
            end
            else begin
                next_state = st_addr16;
            end
        end
        st_addr8: begin                         //8位字地址
            if(st_done) begin
                if(wr_flag==1'b0)               //读写判断
                    next_state = st_data_wr;
                else
                    next_state = st_addr_rd;
            end
            else begin
                next_state = st_addr8;
            end
        end
        st_data_wr: begin                       //写数据(8 bit)
            if(st_done)
                next_state = st_stop;
            else
                next_state = st_data_wr;
        end
        st_addr_rd: begin                       //写地址以进行读数据
            if(st_done) begin
                next_state = st_data_rd;
            end
            else begin
                next_state = st_addr_rd;
            end
        end
        st_data_rd: begin                       //读取数据(8 bit)
            if(st_done)
                next_state = st_stop;
            else
                next_state = st_data_rd;
        end
        st_stop: begin                          //结束I2C操作
            if(st_done)
                next_state = st_idle;
            else
                next_state = st_stop ;
        end
        default: next_state= st_idle;
    endcase
end

//时序电路描述状态输出
always @(posedge dri_clk or negedge rst_n) begin
    //复位初始化
    if(!rst_n) begin
        scl       <= 1'b1;
        sda_out   <= 1'b1;
        sda_dir   <= 1'b1;                          
        i2c_done  <= 1'b0;                          
        i2c_ack   <= 1'b0;                          
        cnt       <= 1'b0;                          
        st_done   <= 1'b0;                          
        data_r    <= 1'b0;                          
        i2c_data_r<= 1'b0;                          
        wr_flag   <= 1'b0;                          
        addr_t    <= 1'b0;                          
        data_wr_t <= 1'b0;                          
    end                                              
    else begin                                       
        st_done <= 1'b0 ;                            
        cnt     <= cnt +1'b1 ;                       
        case(cur_state)                              
             st_idle: begin                          //空闲状态
                scl     <= 1'b1;                     
                sda_out <= 1'b1;                     
                sda_dir <= 1'b1;                     
                i2c_done<= 1'b0;                     
                cnt     <= 7'b0;               
                if(i2c_exec) begin                   
                    wr_flag   <= i2c_rh_wl ;         
                    addr_t    <= i2c_addr  ;         
                    data_wr_t <= i2c_data_w;  
                    i2c_ack   <= 1'b0;                      
                end                                  
            end                                      
            st_sladdr: begin                         //写地址(器件地址和字地址)
                case(cnt)                            
                    7'd1 : sda_out <= 1'b0;          //开始I2C
                    7'd3 : scl <= 1'b0;              
                    7'd4 : sda_out <= SLAVE_ADDR[6]; //传送器件地址
                    7'd5 : scl <= 1'b1;              
                    7'd7 : scl <= 1'b0;              
                    7'd8 : sda_out <= SLAVE_ADDR[5]; 
                    7'd9 : scl <= 1'b1;              
                    7'd11: scl <= 1'b0;              
                    7'd12: sda_out <= SLAVE_ADDR[4]; 
                    7'd13: scl <= 1'b1;              
                    7'd15: scl <= 1'b0;              
                    7'd16: sda_out <= SLAVE_ADDR[3]; 
                    7'd17: scl <= 1'b1;              
                    7'd19: scl <= 1'b0;              
                    7'd20: sda_out <= SLAVE_ADDR[2]; 
                    7'd21: scl <= 1'b1;              
                    7'd23: scl <= 1'b0;              
                    7'd24: sda_out <= SLAVE_ADDR[1]; 
                    7'd25: scl <= 1'b1;              
                    7'd27: scl <= 1'b0;              
                    7'd28: sda_out <= SLAVE_ADDR[0]; 
                    7'd29: scl <= 1'b1;              
                    7'd31: scl <= 1'b0;              
                    7'd32: sda_out <= 1'b0;          //0:写
                    7'd33: scl <= 1'b1;              
                    7'd35: scl <= 1'b0;              
                    7'd36: begin                     
                        sda_dir <= 1'b0;             
                        sda_out <= 1'b1;                         
                    end                              
                    7'd37: scl     <= 1'b1;            
                    7'd38: begin                     //从机应答 
                        st_done <= 1'b1;
                        if(sda_in == 1'b1)           //高电平表示未应答
                            i2c_ack <= 1'b1;         //拉高应答标志位     
                    end                                          
                    7'd39: begin                     
                        scl <= 1'b0;                 
                        cnt <= 1'b0;                 
                    end                              
                    default :  ;                     
                endcase                              
            end                                      
            st_addr16: begin                         
                case(cnt)                            
                    7'd0 : begin                     
                        sda_dir <= 1'b1 ;            
                        sda_out <= addr_t[15];       //传送字地址
                    end                              
                    7'd1 : scl <= 1'b1;              
                    7'd3 : scl <= 1'b0;              
                    7'd4 : sda_out <= addr_t[14];    
                    7'd5 : scl <= 1'b1;              
                    7'd7 : scl <= 1'b0;              
                    7'd8 : sda_out <= addr_t[13];    
                    7'd9 : scl <= 1'b1;              
                    7'd11: scl <= 1'b0;              
                    7'd12: sda_out <= addr_t[12];    
                    7'd13: scl <= 1'b1;              
                    7'd15: scl <= 1'b0;              
                    7'd16: sda_out <= addr_t[11];    
                    7'd17: scl <= 1'b1;              
                    7'd19: scl <= 1'b0;              
                    7'd20: sda_out <= addr_t[10];    
                    7'd21: scl <= 1'b1;              
                    7'd23: scl <= 1'b0;              
                    7'd24: sda_out <= addr_t[9];     
                    7'd25: scl <= 1'b1;              
                    7'd27: scl <= 1'b0;              
                    7'd28: sda_out <= addr_t[8];     
                    7'd29: scl <= 1'b1;              
                    7'd31: scl <= 1'b0;              
                    7'd32: begin                     
                        sda_dir <= 1'b0;             
                        sda_out <= 1'b1;   
                    end                              
                    7'd33: scl  <= 1'b1;             
                    7'd34: begin                     //从机应答
                        st_done <= 1'b1;     
                        if(sda_in == 1'b1)           //高电平表示未应答
                            i2c_ack <= 1'b1;         //拉高应答标志位    
                    end        
                    7'd35: begin                     
                        scl <= 1'b0;                 
                        cnt <= 1'b0;                 
                    end                              
                    default :  ;                     
                endcase                              
            end                                      
            st_addr8: begin                          
                case(cnt)                            
                    7'd0: begin                      
                       sda_dir <= 1'b1 ;             
                       sda_out <= addr_t[7];         //字地址
                    end                              
                    7'd1 : scl <= 1'b1;              
                    7'd3 : scl <= 1'b0;              
                    7'd4 : sda_out <= addr_t[6];     
                    7'd5 : scl <= 1'b1;              
                    7'd7 : scl <= 1'b0;              
                    7'd8 : sda_out <= addr_t[5];     
                    7'd9 : scl <= 1'b1;              
                    7'd11: scl <= 1'b0;              
                    7'd12: sda_out <= addr_t[4];     
                    7'd13: scl <= 1'b1;              
                    7'd15: scl <= 1'b0;              
                    7'd16: sda_out <= addr_t[3];     
                    7'd17: scl <= 1'b1;              
                    7'd19: scl <= 1'b0;              
                    7'd20: sda_out <= addr_t[2];     
                    7'd21: scl <= 1'b1;              
                    7'd23: scl <= 1'b0;              
                    7'd24: sda_out <= addr_t[1];     
                    7'd25: scl <= 1'b1;              
                    7'd27: scl <= 1'b0;              
                    7'd28: sda_out <= addr_t[0];     
                    7'd29: scl <= 1'b1;              
                    7'd31: scl <= 1'b0;              
                    7'd32: begin                     
                        sda_dir <= 1'b0;         
                        sda_out <= 1'b1;                    
                    end                              
                    7'd33: scl     <= 1'b1;          
                    7'd34: begin                     //从机应答
                        st_done <= 1'b1;     
                        if(sda_in == 1'b1)           //高电平表示未应答
                            i2c_ack <= 1'b1;         //拉高应答标志位    
                    end   
                    7'd35: begin                     
                        scl <= 1'b0;                 
                        cnt <= 1'b0;                 
                    end                              
                    default :  ;                     
                endcase                              
            end                                      
            st_data_wr: begin                        //写数据(8 bit)
                case(cnt)                            
                    7'd0: begin                      
                        sda_out <= data_wr_t[7];     //I2C写8位数据
                        sda_dir <= 1'b1;             
                    end                              
                    7'd1 : scl <= 1'b1;              
                    7'd3 : scl <= 1'b0;              
                    7'd4 : sda_out <= data_wr_t[6];  
                    7'd5 : scl <= 1'b1;              
                    7'd7 : scl <= 1'b0;              
                    7'd8 : sda_out <= data_wr_t[5];  
                    7'd9 : scl <= 1'b1;              
                    7'd11: scl <= 1'b0;              
                    7'd12: sda_out <= data_wr_t[4];  
                    7'd13: scl <= 1'b1;              
                    7'd15: scl <= 1'b0;              
                    7'd16: sda_out <= data_wr_t[3];  
                    7'd17: scl <= 1'b1;              
                    7'd19: scl <= 1'b0;              
                    7'd20: sda_out <= data_wr_t[2];  
                    7'd21: scl <= 1'b1;              
                    7'd23: scl <= 1'b0;              
                    7'd24: sda_out <= data_wr_t[1];  
                    7'd25: scl <= 1'b1;              
                    7'd27: scl <= 1'b0;              
                    7'd28: sda_out <= data_wr_t[0];  
                    7'd29: scl <= 1'b1;              
                    7'd31: scl <= 1'b0;              
                    7'd32: begin                     
                        sda_dir <= 1'b0;           
                        sda_out <= 1'b1;                              
                    end                              
                    7'd33: scl <= 1'b1;              
                    7'd34: begin                     //从机应答
                        st_done <= 1'b1;     
                        if(sda_in == 1'b1)           //高电平表示未应答
                            i2c_ack <= 1'b1;         //拉高应答标志位    
                    end          
                    7'd35: begin                     
                        scl  <= 1'b0;                
                        cnt  <= 1'b0;                
                    end                              
                    default  :  ;                    
                endcase                              
            end                                      
            st_addr_rd: begin                        //写地址以进行读数据
                case(cnt)                            
                    7'd0 : begin                     
                        sda_dir <= 1'b1;             
                        sda_out <= 1'b1;             
                    end                              
                    7'd1 : scl <= 1'b1;              
                    7'd2 : sda_out <= 1'b0;          //重新开始
                    7'd3 : scl <= 1'b0;              
                    7'd4 : sda_out <= SLAVE_ADDR[6]; //传送器件地址
                    7'd5 : scl <= 1'b1;              
                    7'd7 : scl <= 1'b0;              
                    7'd8 : sda_out <= SLAVE_ADDR[5]; 
                    7'd9 : scl <= 1'b1;              
                    7'd11: scl <= 1'b0;              
                    7'd12: sda_out <= SLAVE_ADDR[4]; 
                    7'd13: scl <= 1'b1;              
                    7'd15: scl <= 1'b0;              
                    7'd16: sda_out <= SLAVE_ADDR[3]; 
                    7'd17: scl <= 1'b1;              
                    7'd19: scl <= 1'b0;              
                    7'd20: sda_out <= SLAVE_ADDR[2]; 
                    7'd21: scl <= 1'b1;              
                    7'd23: scl <= 1'b0;              
                    7'd24: sda_out <= SLAVE_ADDR[1]; 
                    7'd25: scl <= 1'b1;              
                    7'd27: scl <= 1'b0;              
                    7'd28: sda_out <= SLAVE_ADDR[0]; 
                    7'd29: scl <= 1'b1;              
                    7'd31: scl <= 1'b0;              
                    7'd32: sda_out <= 1'b1;          //1:读
                    7'd33: scl <= 1'b1;              
                    7'd35: scl <= 1'b0;              
                    7'd36: begin                     
                        sda_dir <= 1'b0;            
                        sda_out <= 1'b1;                    
                    end
                    7'd37: scl     <= 1'b1;
                    7'd38: begin                     //从机应答
                        st_done <= 1'b1;     
                        if(sda_in == 1'b1)           //高电平表示未应答
                            i2c_ack <= 1'b1;         //拉高应答标志位    
                    end   
                    7'd39: begin
                        scl <= 1'b0;
                        cnt <= 1'b0;
                    end
                    default : ;
                endcase
            end
            st_data_rd: begin                        //读取数据(8 bit)
                case(cnt)
                    7'd0: sda_dir <= 1'b0;
                    7'd1: begin
                        data_r[7] <= sda_in;
                        scl       <= 1'b1;
                    end
                    7'd3: scl  <= 1'b0;
                    7'd5: begin
                        data_r[6] <= sda_in ;
                        scl       <= 1'b1   ;
                    end
                    7'd7: scl  <= 1'b0;
                    7'd9: begin
                        data_r[5] <= sda_in;
                        scl       <= 1'b1  ;
                    end
                    7'd11: scl  <= 1'b0;
                    7'd13: begin
                        data_r[4] <= sda_in;
                        scl       <= 1'b1  ;
                    end
                    7'd15: scl  <= 1'b0;
                    7'd17: begin
                        data_r[3] <= sda_in;
                        scl       <= 1'b1  ;
                    end
                    7'd19: scl  <= 1'b0;
                    7'd21: begin
                        data_r[2] <= sda_in;
                        scl       <= 1'b1  ;
                    end
                    7'd23: scl  <= 1'b0;
                    7'd25: begin
                        data_r[1] <= sda_in;
                        scl       <= 1'b1  ;
                    end
                    7'd27: scl  <= 1'b0;
                    7'd29: begin
                        data_r[0] <= sda_in;
                        scl       <= 1'b1  ;
                    end
                    7'd31: scl  <= 1'b0;
                    7'd32: begin
                        sda_dir <= 1'b1;             
                        sda_out <= 1'b1;
                    end
                    7'd33: scl     <= 1'b1;
                    7'd34: st_done <= 1'b1;          //非应答
                    7'd35: begin
                        scl <= 1'b0;
                        cnt <= 1'b0;
                        i2c_data_r <= data_r;
                    end
                    default  :  ;
                endcase
            end
            st_stop: begin                           //结束I2C操作
                case(cnt)
                    7'd0: begin
                        sda_dir <= 1'b1;             //结束I2C
                        sda_out <= 1'b0;
                    end
                    7'd1 : scl     <= 1'b1;
                    7'd3 : sda_out <= 1'b1;
                    7'd15: st_done <= 1'b1;
                    7'd16: begin
                        cnt      <= 1'b0;
                        i2c_done <= 1'b1;            //向上层模块传递I2C结束信号
                    end
                    default  : ;
                endcase
            end
        endcase
    end
end    
    
endmodule

LED的报警模块【led_alarm.v】

`timescale 1ns / 1ps
//
// Company: 
// Engineer: 
// 
// Create Date: 2022/07/21 22:03:45
// Design Name: 
// Module Name: led_alarm
// Project Name: 
// Target Devices: 
// Tool Versions: 
// Description: 
// 
// Dependencies: 
// 
// Revision:
// Revision 0.01 - File Created
// Additional Comments:
// 
//


module led_alarm #(parameter L_TIME = 25'd25_000_000)
    (
    input        clk       ,  //时钟信号
    input        rst_n     ,  //复位信号
                 
    input        rw_done   ,  //错误标志
    input        rw_result ,  //E2PROM读写测试完成
    output  reg  led          //E2PROM读写测试结果 0:失败 1:成功
    );
    
//reg define
reg          rw_done_flag;    //读写测试完成标志
reg  [24:0]  led_cnt     ;    //led计数

//*****************************************************
//**                    main code
//*****************************************************    

always @(posedge clk or negedge rst_n)begin
    if(!rst_n)
        rw_done_flag <= 1'b0;
    else if(rw_done)
        rw_done_flag <= 1'b1;
end    

//错误标志为1时PL_LED0闪烁,否则PL_LED0常亮
always @(posedge clk or negedge rst_n) begin
    if(!rst_n)begin
        led_cnt <= 25'd0;
        led <= 1'b0;
    end
    else begin
        if(rw_done_flag)begin
            if(rw_result)
                led <= 1'b1;
            else begin
                led_cnt <= led_cnt + 25'd1;
                if(led_cnt == L_TIME - 1'b1)begin
                    led_cnt <= 25'd0;
                    led <= ~led;
                end
            end
        end
        else
            led <= 1'b0;
    end
end
    
endmodule

EEPROM的读写判断模块【eeprom_rw.v】
该部分逻辑较为简单,使用单段式状态机实现(状态跳转及状态动作在单段代码实现)。

`timescale 1ns / 1ps
//
// Company: 
// Engineer: 
// 
// Create Date: 2022/07/21 21:34:30
// Design Name: 
// Module Name: eeprom_rw
// Project Name: 
// Target Devices: 
// Tool Versions: 
// Description: 
// 
// Dependencies: 
// 
// Revision:
// Revision 0.01 - File Created
// Additional Comments:
// 
//


module eeprom_rw(
    input                 clk        , //时钟信号
    input                 rst_n      , //复位信号

    //i2c interface
    output   reg          i2c_rh_wl  , //I2C读写控制信号
    output   reg          i2c_exec   , //I2C触发执行信号
    output   reg  [15:0]  i2c_addr   , //I2C器件内地址
    output   reg  [ 7:0]  i2c_data_w , //I2C要写的数据
    input         [ 7:0]  i2c_data_r , //I2C读出的数据
    input                 i2c_done   , //I2C一次操作完成
    input                 i2c_ack    , //I2C应答标志

    //user interface
    output   reg          rw_done    , //E2PROM读写测试完成
    output   reg          rw_result    //E2PROM读写测试结果 0:失败 1:成功
    );

//parameter define
//EEPROM写数据需要添加间隔时间,读数据则不需要
parameter      WR_WAIT_TIME = 14'd5000; //写入间隔时间
parameter      MAX_BYTE     = 16'd256 ; //读写测试的字节个数

//reg define
reg   [1:0]    flow_cnt  ; //状态流控制
reg   [13:0]   wait_cnt  ; //延时计数器

//*****************************************************
//**                    main code
//*****************************************************
//EEPROM读写测试,先写后读,并比较读出的值与写入的值是否一致
always @(posedge clk or negedge rst_n) begin
    if(!rst_n) begin
        flow_cnt   <= 2'b0;
        i2c_rh_wl  <= 1'b0;
        i2c_exec   <= 1'b0;
        i2c_addr   <= 16'b0;
        i2c_data_w <= 8'b0;
        wait_cnt   <= 14'b0;
        rw_done    <= 1'b0;
        rw_result  <= 1'b0;        
    end
    else begin
        i2c_exec <= 1'b0;
        rw_done  <= 1'b0;
        case(flow_cnt)
            2'd0 : begin                                  
                wait_cnt <= wait_cnt + 1'b1;               //延时计数
                if(wait_cnt == WR_WAIT_TIME - 1'b1) begin  //EEPROM写操作延时完成
                    wait_cnt <= 1'b0;
                    if(i2c_addr == MAX_BYTE) begin         //256个字节写入完成
                        i2c_addr  <= 1'b0;
                        i2c_rh_wl <= 1'b1;
                        flow_cnt  <= 2'd2;
                    end
                    else begin
                        flow_cnt <= flow_cnt + 1'b1;
                        i2c_exec <= 1'b1;
                    end
                end
            end
            2'd1 : begin
                if(i2c_done == 1'b1) begin                  //EEPROM单次写入完成
                    flow_cnt   <= 2'd0;
                    i2c_addr   <= i2c_addr + 1'b1;           //地址0~255分别写入
                    i2c_data_w <= i2c_data_w + 1'b1;         //数据0~255
                end    
            end
            2'd2 : begin                                   
                flow_cnt <= flow_cnt + 1'b1;
                i2c_exec <= 1'b1;
            end    
            2'd3 : begin
                if(i2c_done == 1'b1) begin                 //EEPROM单次读出完成
                    //读出的值错误或者I2C未应答,读写测试失败
                    if((i2c_addr[7:0] != i2c_data_r) || (i2c_ack == 1'b1)) begin
                        rw_done <= 1'b1;
                        rw_result <= 1'b1;
                    end
                    else if(i2c_addr == MAX_BYTE - 1'b1) begin //读写测试成功
                        rw_done   <= 1'b1;
                        rw_result <= 1'b0;
                    end    
                    else begin
                        flow_cnt <= 2'd2;
                        i2c_addr <= i2c_addr + 1'b1;
                    end
                end                 
            end
            default : ;
        endcase    
    end
end        
    
    
endmodule

完成代码编辑后,将代码编译为二进制流,并下载到FPGA上。

实验结果

按下复位后,经过一小段时间,EEPROM读写模块校正成功,LED开始闪烁

至此,实验成功,IIC功能模块能够移植使用。

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