IIC驱动EEPROM

代码参考正点原子

i2c_dri:主要是三段式状态机的编写

module iic_dri#(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)，1代表字地址是16位的，0是8位的input                i2c_rh_wl  ,  //I2C读写控制信号     ，1代表读数据，0代表写数据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) beginif(!rst_n) begindri_clk <=  1'b0;clk_cnt <= 10'd0;endelse if(clk_cnt == clk_divide[8:1] - 1'd1) beginclk_cnt <= 10'd0;dri_clk <= ~dri_clk;endelseclk_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) beginif(!rst_n)cur_state <= st_idle;elsecur_state <= next_state;
end//组合逻辑判断状态转移条件
always @(*) beginnext_state = st_idle;    //清除锁存器case(cur_state)st_idle: begin                          //空闲状态if(i2c_exec) beginnext_state = st_sladdr;  //器件地址endelsenext_state = st_idle;endst_sladdr: beginif(st_done) beginif(bit_ctrl)                    //判断是16位还是8位字地址next_state = st_addr16;      //字地址的高8位elsenext_state = st_addr8 ;      //字地址的低8位endelsenext_state = st_sladdr;endst_addr16: begin                        //写16位字地址if(st_done) beginnext_state = st_addr8;endelse beginnext_state = st_addr16;endendst_addr8: begin                         //8位字地址if(st_done) beginif(wr_flag==1'b0)               //读写判断next_state = st_data_wr;elsenext_state = st_addr_rd;endelse beginnext_state = st_addr8;endendst_data_wr: begin                       //写数据(8 bit)if(st_done)next_state = st_stop;elsenext_state = st_data_wr;endst_addr_rd: begin                       //写地址以进行读数据if(st_done) beginnext_state = st_data_rd;endelse beginnext_state = st_addr_rd;endendst_data_rd: begin                       //读取数据(8 bit)if(st_done)next_state = st_stop;elsenext_state = st_data_rd;endst_stop: begin                          //结束I2C操作if(st_done)next_state = st_idle;elsenext_state = st_stop ;enddefault: 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) beginscl       <= 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;                     //当sda_dir为1时，sda_out就是sda  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    起始信号 7'd3 : scl <= 1'b0;              //scl在3、5、7、9...时0 1 0 1变化，四分频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  表示接着写 7'd33: scl <= 1'b1;              7'd35: scl <= 1'b0;              7'd36: begin                     sda_dir <= 1'b0;       //拉低释放总线       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  0表示有效应答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i2c_addrend                              7'd1 : scl <= 1'b1;              //四分频          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     data_wr_t要写的数据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;                    end7'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: beginscl <= 1'b0;cnt <= 1'b0;enddefault : ;endcaseendst_data_rd: begin                        //读取数据(8 bit)case(cnt)7'd0: sda_dir <= 1'b0;7'd1: begindata_r[7] <= sda_in;scl       <= 1'b1;end7'd3: scl  <= 1'b0;7'd5: begindata_r[6] <= sda_in ;scl       <= 1'b1   ;end7'd7: scl  <= 1'b0;7'd9: begindata_r[5] <= sda_in;scl       <= 1'b1  ;end7'd11: scl  <= 1'b0;7'd13: begindata_r[4] <= sda_in;scl       <= 1'b1  ;end7'd15: scl  <= 1'b0;7'd17: begindata_r[3] <= sda_in;scl       <= 1'b1  ;end7'd19: scl  <= 1'b0;7'd21: begindata_r[2] <= sda_in;scl       <= 1'b1  ;end7'd23: scl  <= 1'b0;7'd25: begindata_r[1] <= sda_in;scl       <= 1'b1  ;end7'd27: scl  <= 1'b0;7'd29: begindata_r[0] <= sda_in;scl       <= 1'b1  ;end7'd31: scl  <= 1'b0;7'd32: beginsda_dir <= 1'b1;             sda_out <= 1'b1;end7'd33: scl     <= 1'b1;7'd34: st_done <= 1'b1;          //非应答7'd35: beginscl <= 1'b0;cnt <= 1'b0;i2c_data_r <= data_r;enddefault  :  ;endcaseendst_stop: begin                           //结束I2C操作case(cnt)7'd0: beginsda_dir <= 1'b1;             //结束I2Csda_out <= 1'b0;end7'd1 : scl     <= 1'b1;7'd3 : sda_out <= 1'b1;7'd15: st_done <= 1'b1;7'd16: begincnt      <= 1'b0;i2c_done <= 1'b1;            //向上层模块传递I2C结束信号enddefault  : ;endcaseendendcaseend
end

EEPROM读写测试模块：

module e2prom_rw(input              clk ,input              rst_n ,output reg        i2c_rh_wl,output reg        i2c_exec,output reg [15:0] i2c_addr, //i2c器件内地址output reg [7:0]  i2c_data_w,input       [7:0]  i2c_data_r,input              i2c_done,input              i2c_ack,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'd50000;  //5ms写入数据的间隔时间为5msparameter   MAX_BYTE     = 16'd256;    //读写测试的字节个数//reg definereg [1:0] flow_cnt;  //状态流控制reg [13:0] wait_cnt;  //延时计数器//EEPROM读写测试，先写后读，并比较读出的值与输入的值是否一致always @(posedge clk or negedge rst_n)beginif(!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;endelse begin i2c_exec <= 1'b0;rw_done  <= 1'b0;case(flow_cnt)2'd0 : beginwait_cnt <= wait_cnt + 1'b1;if(wait_cnt == (WR_WAIT_TIME  - 1'b1))beginwait_cnt <= 14'b0;if(i2c_addr == MAX_BYTE)begini2c_addr <= 16'b0;i2c_rh_wl <= 1'b1;flow_cnt  <= 2'd2;endelse beginflow_cnt <= flow_cnt + 2'b1;i2c_exec <= 1'b1;  //启动i2cendendend2'd1 : beginif(i2c_done == 1'b1)beginflow_cnt <= 2'd0;i2c_addr <= i2c_addr + 16'b1;       //0-255i2c_data_w <= i2c_data_w + 8'b1;    //0-255endend2'd2 : beginflow_cnt <= flow_cnt + 2'b1;i2c_exec <= 1'b1;end2'd3 : beginif(i2c_done == 1'b1)begin//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)) beginrw_done <= 1'b1;rw_result <=1'b0;endelse if(i2c_addr == (MAX_BYTE - 16'b1))begin  //读写测试成功rw_done <= 1'b1;rw_result <=1'b1;endelse beginflow_cnt <= 2'd2;i2c_addr <= i2c_addr + 16'b1;endendenddefault : ;endcaseend

 读写结果判定：

reg          rw_done_flag;    //读写测试完成标志
reg  [16:0]  led_cnt     ;    //led计数//*****************************************************
//**                    main code
//*****************************************************//读写测试完成标志rw_done_flag
always @(posedge clk or negedge rst_n) beginif(!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) beginif(!rst_n) beginled_cnt <= 17'd0;led <= 1'b0;endelse beginif(rw_done_flag) beginif(rw_result)                          //读写测试正确led <= 1'b1;                       //led灯常亮else begin                             //读写测试错误led_cnt <= led_cnt + 17'd1;if(led_cnt == (L_TIME - 17'b1)) beginled_cnt <= 17'd0;led <= ~led;                   //led灯闪烁endelseled <= led;endendelseled <= 1'b0;                           //读写测试完成之前,led灯熄灭end    
endendmodule

 top:

module top_e2prom(input               sys_clk    ,      //系统时钟input               sys_rst_n  ,      //系统复位//eeprom interfaceoutput              iic_scl    ,      //eeprom的时钟线sclinout               iic_sda    ,      //eeprom的数据线sda//user interfaceoutput              led               //led显示eeprom读写测试结果
);//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
parameter    MAX_BYTE   = 16'd256        ; //读写测试的字节个数//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
e2prom_rw #(.MAX_BYTE    (MAX_BYTE  )   //读写测试的字节个数
) u_e2prom_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
iic_dri #(.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_dri(.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
rw_result_led #(.L_TIME(L_TIME  )   //控制led闪烁时间
) u_rw_result_led(.clk         (dri_clk   ),  .rst_n       (sys_rst_n ), .rw_done     (rw_done   ),  .rw_result   (rw_result ),.led         (led       )    
);endmodule

tb:时钟激励

`timescale  1ns/1ns                     //定义仿真时间单位1ns和仿真时间精度为1nsmodule  tb_e2prom_top;              //parameter  define
parameter  T = 20                          ; //时钟周期为20ns
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),周期就是20纳秒
parameter  I2C_FREQ       = 18'd250_000    ; //I2C的SCL时钟频率，周期是4us
parameter  L_TIME         = 17'd1          ; //led闪烁时间参数
parameter  MAX_BYTE       = 16'd3          ; //读写测试的字节个数//reg define
reg          sys_clk  ;                 //时钟信号
reg          sys_rst_n;                 //复位信号//wire define
wire         iic_scl;
wire         iic_sda;
wire         led    ;//*****************************************************
//**                    main code
//*****************************************************//给输入信号初始值
initial beginsys_clk            = 1'b0;sys_rst_n          = 1'b0;     //复位#(T+1)  sys_rst_n  = 1'b1;     //在第21ns的时候复位信号信号拉高
end//50Mhz的时钟，周期则为1/50Mhz=20ns,所以每10ns，电平取反一次
always #(T/2) sys_clk = ~sys_clk;//将SDA数据线上拉
pullup(iic_sda);//例化e2prom_top模块
top_e2prom  #(.MAX_BYTE   (MAX_BYTE )   //读写测试的字节个数
) u_top_e2prom(.sys_clk    (sys_clk  ),  //系统时钟.sys_rst_n  (sys_rst_n),  //系统复位//eeprom interface.iic_scl    (iic_scl  ),  //eeprom的时钟线scl.iic_sda    (iic_sda  ),  //eeprom的数据线sda//user interface.led        (led      )   //led显示
);//例化e2prom仿真模型
EEPROM_AT24C64 u_EEPROM_AT24C64(.scl         (iic_scl),.sda         (iic_sda));endmodule

 上拉电阻：

wire abc;
pullup(abc);
assign abc = enable ? 1’b0 : 1’bz;

enable为1的时候 abc信号为0
enable 为0的时候 assign语句的输出为高阻，但是因为pullup了abc，所以abc的值为1

EEPROM仿真模型：

`timescale 1ns/1ns
`define timeslice 1250
module EEPROM_AT24C64(
scl,
sda
);
input scl; 
inout sda; 
reg out_flag; 
reg[7:0] memory[8191:0]; 
reg[12:0]address; 
reg[7:0]memory_buf; 
reg[7:0]sda_buf; 
reg[7:0]shift; 
reg[7:0]addr_byte_h; 
reg[7:0]addr_byte_l; 
reg[7:0]ctrl_byte; 
reg[1:0]State;
integer i;
//---------------------------
parameter
r7 = 8'b1010_1111, w7 = 8'b1010_1110, //main7
r6 = 8'b1010_1101, w6 = 8'b1010_1100, //main6
r5 = 8'b1010_1011, w5 = 8'b1010_1010, //main5
r4 = 8'b1010_1001, w4 = 8'b1010_1000, //main4
r3 = 8'b1010_0111, w3 = 8'b1010_0110, //main3
r2 = 8'b1010_0101, w2 = 8'b1010_0100, //main2
r1 = 8'b1010_0011, w1 = 8'b1010_0010, //main1
r0 = 8'b1010_0001, w0 = 8'b1010_0000; //main0
assign sda = (out_flag == 1) ? sda_buf[7] : 1'bz;initial
begin
addr_byte_h = 0;
addr_byte_l = 0;
ctrl_byte = 0;
out_flag = 0;
sda_buf = 0;
State = 2'b00;
memory_buf = 0;
address = 0;
shift = 0;
for(i=0;i<=8191;i=i+1)
memory[i] = 0;
end
always@(negedge sda)
begin
if(scl == 1)
begin
State = State + 1;
if(State == 2'b11)
disable write_to_eeprom;
end
endalways@(posedge sda)
begin
if(scl == 1) 
stop_W_R;
else
begin
casex(State)
2'b01:begin
read_in;
if(ctrl_byte == w7 || ctrl_byte == w6
|| ctrl_byte == w5 || ctrl_byte == w4
|| ctrl_byte == w3 || ctrl_byte == w2
|| ctrl_byte == w1 || ctrl_byte == w0)
begin
State = 2'b10;
write_to_eeprom; 
end
else
State = 2'b00;
end
2'b11:
read_from_eeprom;
default:
State = 2'b00;
endcase
end
end 
task stop_W_R;
begin
State = 2'b00;
addr_byte_h = 0;
addr_byte_l = 0;
ctrl_byte = 0;
out_flag = 0;
sda_buf = 0;
end
endtasktask read_in;
begin
shift_in(ctrl_byte);
shift_in(addr_byte_h);
shift_in(addr_byte_l);
end
endtasktask write_to_eeprom;
begin
shift_in(memory_buf);
address = {addr_byte_h[4:0], addr_byte_l};
memory[address] = memory_buf;
State = 2'b00;
end
endtasktask read_from_eeprom;
begin
shift_in(ctrl_byte);
if(ctrl_byte == r7 || ctrl_byte == w6
|| ctrl_byte == r5 || ctrl_byte == r4
|| ctrl_byte == r3 || ctrl_byte == r2
|| ctrl_byte == r1 || ctrl_byte == r0)
begin
address = {addr_byte_h[4:0], addr_byte_l};
sda_buf = memory[address];
shift_out;
State = 2'b00;
end
end
endtask
task shift_in;
output[7:0]shift;
begin
@(posedge scl) shift[7] = sda;
@(posedge scl) shift[6] = sda;
@(posedge scl) shift[5] = sda;
@(posedge scl) shift[4] = sda;
@(posedge scl) shift[3] = sda;
@(posedge scl) shift[2] = sda;
@(posedge scl) shift[1] = sda;
@(posedge scl) shift[0] = sda;
@(negedge scl)
begin
#(`timeslice);
out_flag = 1;
sda_buf = 0;
end
@(negedge scl)
begin
#(`timeslice-250);
out_flag = 0;
end
end
endtask
task shift_out;
begin
out_flag = 1;
for(i=6; i>=0; i=i-1)
begin
@(negedge scl);
#`timeslice;
sda_buf = sda_buf << 1;
end
@(negedge scl) #`timeslice sda_buf[7] = 1;
@(negedge scl) #`timeslice out_flag = 0;
end
endtask
endmodule

i2c状态机的编写：

 

读数据： 

i2c第一次写入地址0的字节数据0：

 i2c第二次写入地址1的字节数据1： 

 i2c第三次写入地址2的字节数据2： 

读数据的时候sda总线由输入变为输出状态，需要给从机一个非应答信号，不能给应答信号！给应答信号就不再是任意地址读，就变成了从某个地址连续读，不符合本次设计的任意地址读模式：

 

 

两个毛刺信号：（由EEPROM仿真模型引起的）

上板验证：

        胡萝卜鸡...