参考：http://blog.csdn.net/yuanlulu/article/details/6163106
ROM最初不能编程，出厂什么内容就永远什么内容，不灵活。后来出现了PROM，可以自己写入一次，要是写错了，只能换一片，自认倒霉。人类文明不断进步，终于出现了可多次擦除写入的EPROM，每次擦除要把芯片拿到紫外线上照一下，想一下你往单片机上下了一个程序之后发现有个地方需要加一句话，为此你要把单片机放紫外灯下照半小时，然后才能再下一次，这么折腾一天也改不了几次。历史的车轮不断前进，伟大的EEPROM出现了，拯救了一大批程序员，终于可以随意的修改rom中的内容了
EEPROM的全称是“电可擦除可编程只读存储器”，即Electrically Erasable Programmable Read-Only Memory。是相对于紫外擦除的rom来讲的。但是今天已经存在多种EEPROM的变种，变成了一类存储器的统称.这种rom的特点是可以随机访问和修改任何一个字节，可以往每个bit中写入0或者1。这是最传统的一种EEPROM，掉电后数据不丢失，可以保存100年，可以擦写100w次。具有较高的可靠性，但是电路复杂/成本也高。因此目前的EEPROM都是几十千字节到几百千字节的，绝少有超过512K的。
EEPROM的接口分为两种：SPI和I2C。
SPI接口为四线，型号如AT25XXX。
I2C接口为2线，型号如24CL02/04/XX.
这两种EEPROM的操作主要按SPI 和I2C的协议操作就可以了，不过也有一些需要注意的地方。在这里记录下来，不涉及细节的处理。
对于SPI接口的EEPROM:
1、在写数据的时候需要先写WR_EN的命令，然后在按SPI写写操作。读的时候不需要先写WR_EN.
2、WR_EN 和WR_DATA 的操作之间要隔一段时间，如10us,不能写完WR_EN就写WR_DATA，否则数据将不能被写入。
3、WR_DATA操作送入EEPROM之后，要等待一段时间，等EEPROM将数据写入内部，时间长短可以参考datasheet中的一个参数 write_cycle。
4、RD_DATA操作到下一次的WR_EN/WR_DATA命令之间也要间隔一段时间，如400us.
5、SPI协议的最后一个SPI_CLK也要保证完整，有低有高，不能只有一半，如将SPI_CLK拉高之后不拉低就将SPI_CS信号拉低。
example: verilog
EEPROM--SPI interface
module EE_WR(//------------outputs-----------output EE_SI, output EE_CSb,output EE_SCK, input EE_SO,//------------inputs------------input clk,//50MHZinput rst)/*synthesis noprune*/; parameter cmd_wr_en =8'h06 /* synthesis keep */; parameter cmd_wr_sr =16'h0180 /* synthesis keep */; //16'h018C all block are protected parameter cmd_rd_sr =8'h05 /* synthesis keep */; parameter cmd_wr_op =536'h020000_63555560595857565554535251504948474645444342414039383736353433323130292827262524232221201918171615141312111009080706050403020100 /* synthesis keep */; //parameter cmd_wr_op =32'h020000_f5 /* synthesis keep */; parameter cmd_rd_op =24'h030000 /* synthesis keep */; parameter tck_delay = 4'd6; parameter num_data_bit = 12'd512; parameter IDLE = 5'd0; parameter WR_EN_1 = 5'd1; parameter WR_EN_2 = 5'd2; parameter WR_EN_3 = 5'd3; parameter WR_EN_4 = 5'd4; parameter WR_EN_5 = 5'd5; parameter WR_SR_1 = 5'd6; parameter WR_SR_2 = 5'd7; parameter WR_SR_3 = 5'd8; parameter WR_SR_4 = 5'd9; parameter WR_SR_5 = 5'd10; parameter RD_SR_1 = 5'd11; parameter RD_SR_2 = 5'd12; parameter RD_SR_3 = 5'd13; parameter RD_SR_4 = 5'd14; parameter RD_SR_5 = 5'd15; parameter RD_SR_6 = 5'd16; parameter RD_SR_7 = 5'd17; parameter WR_DATA_1 = 5'd18; parameter WR_DATA_2 = 5'd19; parameter WR_DATA_3 = 5'd20; parameter WR_DATA_4 = 5'd21; parameter WR_DATA_5 = 5'd22; parameter RD_DATA_1 = 5'd23; parameter RD_DATA_2 = 5'd24; parameter RD_DATA_3 = 5'd25; parameter RD_DATA_4 = 5'd26; parameter RD_DATA_5 = 5'd27; parameter RD_DATA_6 = 5'd28; parameter RD_DATA_7 = 5'd29; reg [31:0] cnt;always @(posedge clk or negedge rst ) begin if(rst == 0 ) cnt <= 0; else if(cnt == 32'd500_000_000) cnt <= 32'd500_000_000; else cnt <= cnt + 1; end wire wr_en /* synthesis keep */; wire wr_op /* synthesis keep */; wire rd_op /* synthesis keep */; wire rd_sr /* synthesis keep */; wire wr_sr /* synthesis keep */; assign wr_en = (cnt == 32'd000_000_500); assign rd_sr = (cnt == 32'd000_000_000); assign wr_sr = (cnt == 32'd000_000_000); assign wr_op = (cnt == 32'd000_001_000); assign rd_op = (cnt == 32'd001_000_000); reg [4:0] state; reg [3:0] delay; reg [11:0] num; reg [7:0] data_sr; reg [7:0] data_rd; reg spi_clk; reg spi_cs; reg spi_si; always @(posedge clk or negedge rst ) begin if(rst == 0 ) begin spi_clk <= 0; spi_cs <= 1; spi_si <= 0; delay <= 0; num <= 0; state <= IDLE; data_sr <= 0; data_rd<= 0; end else begin case(state) IDLE : begin spi_clk <= 0; spi_cs <= 1; spi_si <= 0; delay <= 0; num <= 0; data_sr <= 0; data_rd <= 0; if(wr_en) state <= WR_EN_1; // else if(wr_sr) state <= WR_SR_1; // else if(rd_sr) state <= RD_SR_1; else if(wr_op) state <= WR_DATA_1; else if(rd_op) state <= RD_DATA_1 ; else state <= state; end//-------------wr_en------------- WR_EN_1: begin //拉低CS spi_clk <= 0; spi_cs <= 0; num <= 7; if(delay == tck_delay) begin state <= state + 1; delay <= 0; end else begin state <= state; delay <= delay + 1; end end WR_EN_2: begin //sck 下降沿 spi_clk <= 0; spi_si <= cmd_wr_en[num]; if(delay == tck_delay) begin state <= state + 1; delay <= 0; end else begin state <= state; delay <= delay + 1; end end WR_EN_3: begin //sck 上升沿 spi_clk <= 1; spi_si <= spi_si; if(delay == tck_delay) begin if(num == 0) begin state <= state + 1; delay <= 0; end else begin state <= WR_EN_2; delay <= 0; num <= num - 1; end end else begin state <= state; delay <= delay + 1; end end WR_EN_4: begin //SCK 下降沿延时一个 spi_clk <= 0; spi_si <= spi_si; if(delay == tck_delay) begin state <= state + 1; delay <= 0; end else begin state <= state; delay <= delay + 1; end end WR_EN_5: begin //CS 拉高 spi_cs <= 1; spi_clk<= 0; spi_si <= 0; if(delay == tck_delay) begin state <= IDLE; delay <= 0; end else begin state <= state; delay <= delay + 1; end end //-------------wr_sr------------- WR_SR_1: begin //拉低CS spi_clk <= 0; spi_cs <= 0; num <= 15; spi_si <= 0; if(delay == tck_delay) begin state <= state + 1; delay <= 0; end else begin state <= state; delay <= delay + 1; end end WR_SR_2: begin //sck 下降沿 spi_clk <= 0; spi_si <= cmd_wr_sr[num]; if(delay == tck_delay) begin state <= state + 1; delay <= 0; end else begin state <= state; delay <= delay + 1; end end WR_SR_3: begin //sck 上升沿 spi_clk <= 1; spi_si <= spi_si; if(delay == tck_delay) begin if(num == 0) begin state <= state + 1; delay <= 0; end else begin state <= WR_SR_2; delay <= 0; num <= num -1; end end else begin state <= state; delay <= delay + 1; end end WR_SR_4: begin //SCK 下降沿延时一个 spi_clk <= 0; spi_si <= spi_si; if(delay == tck_delay) begin state <= state + 1; delay <= 0; end else begin state <= state; delay <= delay + 1; end end WR_SR_5: begin //CS 拉高 spi_cs <= 1; spi_clk<= 0; spi_si <= 0; if(delay == tck_delay) begin state <= IDLE; delay <= 0; end else begin state <= state; delay <= delay + 1; end end //-----rd_sr----------- RD_SR_1: begin //拉低CS spi_clk <= 0; spi_cs <= 0; num <= 7; data_sr <= 0; spi_si <= 0; if(delay == tck_delay) begin state <= state + 1; delay <= 0; end else begin state <= state; delay <=delay + 1; end end RD_SR_2: begin //sck 下降沿 spi_clk <= 0; spi_si <= cmd_rd_sr[num]; if(delay == tck_delay) begin state <= state + 1; delay <= 0; end else begin state <= state; delay <= delay + 1; end end RD_SR_3: begin //sck 上升沿 spi_clk <= 1; spi_si <= spi_si; if(delay == tck_delay) begin if(num == 0) begin state <= state + 1; delay <= 0; num <= 7; end else begin state <= RD_SR_2; delay <= 0; num <= num - 1; end end else begin state <= state; delay <= delay + 1; end end RD_SR_4: begin //read SCK 下降沿 spi_clk <= 0; spi_si <= 0; data_sr <= data_sr; if(delay == tck_delay) begin state <= state + 1; delay <= 0; end else begin state <= state; delay <= delay + 1; end end RD_SR_5: begin //READ sck 上升沿 spi_clk <= 1; data_sr[num] <= EE_SO; if(delay == tck_delay) begin if(num == 0) begin state <= state + 1; delay <= 0; end else begin state <= RD_SR_4; delay <= 0; num <= num - 1; end end else begin state <= state; delay <= delay + 1; end end RD_SR_6: begin //SCK 下降沿延时一个 spi_clk <= 0; data_sr <= data_sr; if(delay == tck_delay) begin state <= state + 1; delay <= 0; end else begin state <= state; delay <= delay + 1; end end RD_SR_7: begin //CS拉高 spi_cs <= 1; spi_clk<= 0; spi_si <= 0; if(delay == tck_delay) begin state <= IDLE; delay <= 0; end else begin state <= state; delay <= delay + 1; end end //---------------------wr_data------------------ WR_DATA_1: begin //拉低CS spi_clk <= 0; spi_cs <= 0; spi_si <= 0; num <= num_data_bit + 23; if(delay == tck_delay) begin state <= state + 1; delay <= 0; end else begin state <= state; delay <= delay + 1; end end WR_DATA_2: begin //SCK下降沿 spi_clk <= 0; spi_si <= cmd_wr_op[num]; if(delay == tck_delay) begin state <= state + 1; delay <= 0; end else begin state <= state; delay <= delay + 1; end end WR_DATA_3: begin //SCK 上升沿 spi_clk <= 1; spi_si <= spi_si; if(delay == tck_delay) begin if(num == 0) begin state <= state + 1; delay <= 0; end else begin state <= WR_DATA_2; delay <= 0; num <= num - 1; end end else begin state <= state; delay <= delay + 1; end end WR_DATA_4: begin //SCK延时下降沿 spi_clk <= 0; spi_si <= 0; if(delay == tck_delay) begin state <= state + 1; delay <= 0; end else begin state <= state; delay <= delay + 1; end end WR_DATA_5: begin //CS拉高 spi_cs <= 1; spi_clk<= 0; spi_si <= 0; if(delay == tck_delay) begin state <= IDLE; delay <= 0; end else begin state <= state; delay <= delay + 1; end end //---------------------rd_data------------------- RD_DATA_1: begin //拉低CS spi_clk <= 0; spi_cs <= 0; spi_si <= 0; num <= 23; if(delay == tck_delay) begin state <= state + 1; delay <= 0; end else begin state <= state; delay <= delay + 1; end end RD_DATA_2: begin //SCK下降沿 spi_clk <= 0; spi_si <= cmd_rd_op[num]; if(delay == tck_delay) begin state <= state + 1; delay <= 0; end else begin state <= state; delay <= delay + 1; end end RD_DATA_3: begin //SCK 上升沿 spi_clk <= 1; spi_si <= spi_si; if(delay == tck_delay) begin if(num == 0) begin state <= state + 1; delay <= 0; num <= num_data_bit - 1; end else begin state <= RD_DATA_2; delay <= 0; num <= num - 1; end end else begin state <= state; delay <= delay + 1; end end RD_DATA_4: begin //read SCK 下降沿 spi_clk <= 0; spi_si <= 0; data_rd <= data_rd; if(delay == tck_delay) begin state <= state + 1; delay <= 0; end else begin state <= state; delay <= delay + 1; end end RD_DATA_5: begin //READ sck 上升沿 spi_clk <= 1; data_rd[num] <= EE_SO; if(delay == tck_delay) begin if(num == 0) begin state <= state + 1; delay <= 0; end else begin state <= RD_DATA_4; delay <= 0; num <= num - 1; end end else begin state <= state; delay <= delay + 1; end end RD_DATA_6: begin //SCK 下降沿延时一个 spi_clk <= 0; data_rd <= data_rd; if(delay == tck_delay) begin state <= state + 1; delay <= 0; end else begin state <= state; delay <= delay + 1; end end RD_DATA_7 :begin //CS拉高 spi_cs <= 1; spi_clk<= 0; spi_si <= 0; if(delay == tck_delay) begin state <= IDLE; delay <= 0; end else begin state <= state; delay <= delay + 1; end end default : state <= 0; endcase endend assign EE_CSb = spi_cs; assign EE_SCK = spi_clk; assign EE_SI = spi_si; endmodule
tb:
`timescale 1 ps/1 ps module EE_WR_tb ; wire EE_SI; wire EE_CSb; wire EE_SCK; reg EE_SO;//------------inputs------------ reg clk;//50MHZ reg rst; EE_WR u0_EE_WR(//------------outputs----------- .EE_SI(EE_SI), .EE_CSb(EE_CSb), .EE_SCK(EE_SCK), .EE_SO(EE_SO), //------------inputs------------ .clk(clk),//50MHZ .rst(rst) )/*synthesis noprune*/; parameter T = 20000; always #(T/2) clk = ~clk; initial begin clk = 0; rst =0; #(300*T) $stop; #(200*T) rst =1; end endmodule
对于I2C的接口：
1、读写之间按I2C的协议进行就可以。
2、在读取数据时候，master在接收完8bit数据之后，需要给从机发一个ACK(输出一个SDA =0)。注意读取的时候ACK是由Master发出的，在写数据的时候ACK是由slaver发出的。
可以参考：http://blog.csdn.net/lingfeng5/article/details/73361833
3、写数据同样也有一定的write_cycle. 参考datasheet.
example: verilog
View Code // `define SIM //if run modelsim, enable module eeprom_data( input clk, input rst_n, output wr_en, output reg [7:0] wr_addr, output reg [7:0] wr_data, output reg wr_flag, output rd_en, output reg [7:0] rd_addr, input [7:0] rd_data, output reg rd_flag, input rd_wrdata_en, //only one clk cycle high time input wr_rddata_en ); reg [7:0] wr_cnt; reg [7:0] rd_cnt; reg [31:0] cnt; reg [5:0] rd_wrdata_en_flag; always @(posedge clk or negedge rst_n) begin if(rst_n == 0) rd_wrdata_en_flag <= 6'd0; else rd_wrdata_en_flag <= {rd_wrdata_en_flag[5:0],rd_wrdata_en}; end `ifdef SIM always @(posedge clk or negedge rst_n) begin if(rst_n == 0) cnt <= 0; else if(cnt == 32'd100_000) cnt <= 0; else cnt <= cnt + 1; end assign wr_en = (cnt == 32'd20_000); assign rd_en = (cnt == 32'd70_000); `else always @(posedge clk or negedge rst_n) begin if(rst_n == 0) cnt <= 0; else if(cnt == 32'd500_000_000) cnt <= 0; else cnt <= cnt + 1; end assign wr_en = (cnt == 32'd200_000_000); assign rd_en = (cnt == 32'd400_000_000); `endif parameter data_num = 8'd16; //the data number of need to be write or read //========================================= //write always @(posedge clk or negedge rst_n) begin if(rst_n == 0) wr_addr <= 0; else if(rd_wrdata_en_flag[5]) begin if(wr_addr == data_num) wr_addr <= 0; else wr_addr <= wr_addr + 1; end else wr_addr <= wr_addr; end always @(posedge clk or negedge rst_n) begin if(rst_n == 0) wr_data <= 0; else if(rd_wrdata_en_flag[5]) begin if(wr_data == data_num) wr_data <= 0; else wr_data <= wr_data + 1; end else wr_data <= wr_data; end always @(posedge clk or negedge rst_n) begin if(rst_n == 0) wr_cnt <= 0; else if(rd_wrdata_en_flag[5]) begin if(wr_cnt == data_num) wr_cnt <= 0; else wr_cnt <= wr_cnt + 1; end else wr_cnt <= wr_cnt; end always @(posedge clk or negedge rst_n) begin if(rst_n == 0) wr_flag <= 0; else if(wr_en) wr_flag <= 1; else if(rd_wrdata_en_flag[5]) begin if(wr_cnt == data_num) wr_flag <= 0; else wr_flag <= 1; end else wr_flag <= wr_flag; end //==================================== //read always @(posedge clk or negedge rst_n) begin if(rst_n == 0) rd_addr <= 0; else if(wr_rddata_en) begin if(rd_addr == data_num) rd_addr <= 0; else rd_addr <= rd_addr + 1; end else rd_addr <= rd_addr; end // always @(posedge clk or negedge rst_n)// begin// if(rst_n == 0) rd_data <= 0;// else if(wr_rddata_en) begin// if(rd_data == 8'D127) rd_data <= 0; // else rd_data <= rd_data + 1;// end // else rd_data <= rd_data;// end// always @(posedge clk or negedge rst_n) begin if(rst_n == 0) rd_cnt <= 0; else if(wr_rddata_en) begin if(rd_cnt == data_num) rd_cnt <= 0; else rd_cnt <= rd_cnt + 1; end else rd_cnt <= rd_cnt; end always @(posedge clk or negedge rst_n) begin if(rst_n == 0) rd_flag <= 0; else if(rd_en) rd_flag <= 1; else if(wr_rddata_en) begin if(data_num == 0) rd_flag <= 0; else if(rd_cnt == (data_num-1)) rd_flag <= 0; else rd_flag <= 1; end else rd_flag <= rd_flag; end wire fifo_empty; wire [4:0] cnt_fifo; wire clr_fifo; assign clr_fifo = wr_rddata_en&&(rd_cnt == (data_num-1)); RD_DATA_BUF u_rd_data_buf( .aclr(clr_fifo), .clock(clk), .data(rd_data), .rdreq(1'b0), .wrreq(wr_rddata_en), .empty(fifo_empty), .full(), .q(), .usedw(cnt_fifo) ); endmodule //====================================== // I2C.v // //==========================// `define SIM //if run modelsim, enable module I2C( input clk, //sysclk = 50Mhz input rst_n, input [1:0] wr_rd_en, //wr_rd_en[1] = read, wr_rd_en[0] = write input wr_data_flag, //if still have data to write,the flag always is high input rd_data_flag, //if still have data to read,the flag always is high input [7:0] wr_addr, input [7:0] wr_data, input [7:0] rd_addr, output [7:0] rd_data, output rd_wrdata_en, //read data from eeprom_data.v to write eeprom output wr_rddata_en, //write the read data from eeprom to eeprom_data.v output ee_I2C_CLK, inout ee_I2C_SDA ); reg [1:0] wr_rd_en_reg1,wr_rd_en_reg2; reg [4:0] state; parameter IDLE = 5'd0; parameter START_1 = 5'd1; parameter START_2 = 5'd2; parameter START_3 = 5'd3; parameter WR_CTL_1 = 5'd4; parameter WR_CTL_2 = 5'd5; parameter WR_CTL_ACK1 = 5'd6; parameter WR_CTL_ACK2 = 5'd7; parameter WR_ADDR_1 = 5'd8; parameter WR_ADDR_2 = 5'd9; parameter WR_ADDR_ACK1 = 5'd10; parameter WR_ADDR_ACK2 = 5'd11; parameter WR_DATA_1 = 5'd12; parameter WR_DATA_2 = 5'd13; parameter WR_DATA_3 = 5'd14; parameter WR_DATA_ACK1 = 5'd15; parameter WR_DATA_ACK2 = 5'd16; parameter RD_DATA_1 = 5'd17; parameter RD_DATA_2 = 5'd18; parameter RD_DATA_ACK1 = 5'd19; parameter RD_DATA_ACK2 = 5'd20; parameter STOP_1 = 5'd21; parameter STOP_2 = 5'd22; parameter STOP_3 = 5'd23; parameter WRITE_TIME = 5'd24; //delay 10ms parameter CMD_control = 7'b1010000; //eeprom addr = 3'b000; `ifdef SIM parameter delay = 20'd100; parameter delay_10ms = 20'd500;`else parameter delay = 20'd300; parameter delay_10ms = 20'd500000;`endif always @(posedge clk or negedge rst_n) begin if(rst_n == 0) begin wr_rd_en_reg2 <= 2'd0; wr_rd_en_reg1 <= 2'd0 ; end else begin wr_rd_en_reg2 <= wr_rd_en_reg1; wr_rd_en_reg1 <= wr_rd_en ; end end reg [4:0] num; //data = 8bit reg [19:0] delay_cnt; reg [7:0] addr_reg; //reg addr reg [7:0] data_reg; //reg data reg wr_flag; //write flag reg rd_flag; //read flag reg rd_restart_flag; // read, the next start flag reg dir_sda_flag; // dir of sda flag reg rd_wrdata_flag; //when write data ,need read data first reg wr_rddata_flag; reg [7:0] rd_data_reg; reg ee_sclk_reg; reg ee_data_reg; always @(posedge clk or negedge rst_n) begin if(rst_n == 0) begin state <= IDLE; num <= 0; delay_cnt <= 0; addr_reg <= 0; data_reg <= 0; wr_flag <= 0; dir_sda_flag <= 0; rd_flag <= 0; rd_restart_flag <= 0; rd_wrdata_flag <= 0; wr_rddata_flag <= 0; rd_data_reg <= 0; ee_sclk_reg <= 1; ee_data_reg <= 1; end else begin case(state) IDLE: begin num <= 0; delay_cnt <= 0; data_reg <= 0; addr_reg <= 0; wr_flag <= 0; dir_sda_flag <= 0; rd_flag <= 0; rd_restart_flag <= 0; rd_wrdata_flag <= 0; wr_rddata_flag <= 0; rd_data_reg <= 0; ee_sclk_reg <= 1; ee_data_reg <= 1; if(wr_rd_en_reg2 == 2'b01) begin //write addr_reg <= wr_addr ; wr_flag <= 1; rd_flag <= 0; state <= START_1; dir_sda_flag <= 1; end else if(wr_rd_en_reg2 == 2'b10) begin //read addr_reg <= rd_addr ; wr_flag <= 0; rd_flag <= 1; state <= START_1; dir_sda_flag <= 1; rd_data_reg <= 0; end else begin state <= state; end end START_1: begin //reg ee_sclk_reg <= 1; ee_data_reg <= 1; if(delay_cnt == delay<<1 ) begin state <= state + 1; delay_cnt <= 0; end else begin state <= state ; delay_cnt <= delay_cnt + 1; end end START_2: begin //pull down DATA ee_sclk_reg <= 1; ee_data_reg <= 0; if(delay_cnt == delay ) begin state <= state + 1; delay_cnt <= 0; end else begin state <= state ; delay_cnt <= delay_cnt + 1; end end START_3: begin //pull down SCL ee_sclk_reg <= 0; ee_data_reg <= 0; num <= 7; if(delay_cnt == delay ) begin delay_cnt <= 0; if(rd_restart_flag) begin data_reg <= {CMD_control,1'b1}; state <= WR_CTL_1; end else if((wr_flag ==1)&&(rd_flag == 0)) begin data_reg <= {CMD_control,1'b0}; state <= WR_CTL_1; end else if((wr_flag == 0)&&(rd_flag == 1)) begin data_reg <= {CMD_control,1'b0}; state <= WR_CTL_1; end else begin data_reg <= 0; state <= IDLE; end end else begin state <= state ; delay_cnt <= delay_cnt + 1; end end WR_CTL_1 : begin //write CMD,change data at middle of SCL low time ee_sclk_reg <= 0; if(delay_cnt == delay>>1) ee_data_reg <= data_reg[num]; else ee_data_reg <= ee_data_reg; if(delay_cnt == delay) begin state <= state + 1; delay_cnt <= 0; end else begin state <= state ; delay_cnt <= delay_cnt + 1; end end WR_CTL_2: begin //write CMD,write data ee_sclk_reg <= 1; ee_data_reg <= ee_data_reg; if(delay_cnt == delay) begin if(num == 0) begin state <= state + 1; delay_cnt <= 0; end else begin state <= WR_CTL_1; delay_cnt <= 0; num <= num -1; end end else begin state <= state ; delay_cnt <= delay_cnt + 1; end end WR_CTL_ACK1 : begin //ack ee_sclk_reg <= 0; ee_data_reg <= 0; if(delay_cnt == 4) dir_sda_flag <= 0; //delay, make sure SDA change in the SCK Low else dir_sda_flag <= dir_sda_flag; if(delay_cnt == delay) begin state <= state + 1; delay_cnt <= 0; end else begin state <= state ; delay_cnt <= delay_cnt + 1; end end WR_CTL_ACK2 : begin ee_sclk_reg <= 1; if(delay_cnt == delay) begin delay_cnt <= 0; if(rd_restart_flag) begin state <= RD_DATA_1; delay_cnt <= 0; num <= 7; rd_restart_flag <= 0; end else begin state <= WR_ADDR_1; num <= 7; end end else begin state <= state ; delay_cnt <= delay_cnt + 1; end end WR_ADDR_1: begin //write addr,change data ee_sclk_reg <= 0; if(delay_cnt == 4) dir_sda_flag <= 1; else dir_sda_flag <= dir_sda_flag; if(delay_cnt == delay>>1) ee_data_reg <= addr_reg[num]; else ee_data_reg <= ee_data_reg; if(delay_cnt == delay) begin state <= state + 1; delay_cnt <= 0; end else begin state <= state ; delay_cnt <= delay_cnt + 1; end end WR_ADDR_2: begin //write addr,WRITE data ee_sclk_reg <= 1; ee_data_reg <= ee_data_reg; if(delay_cnt == delay) begin if(num == 0) begin state <= WR_ADDR_ACK1; delay_cnt <= 0; end else begin state <= WR_ADDR_1; delay_cnt <= 0; num <= num -1; end end else begin state <= state ; delay_cnt <= delay_cnt + 1; end end WR_ADDR_ACK1 : begin ee_sclk_reg <= 0; ee_data_reg <= 0; if(delay_cnt == 4) dir_sda_flag <= 0; else dir_sda_flag <= dir_sda_flag; if(delay_cnt == delay) begin state <= state + 1; delay_cnt <= 0; end else begin state <= state ; delay_cnt <= delay_cnt + 1; end end WR_ADDR_ACK2: begin ee_sclk_reg <= 1; if(delay_cnt == delay) begin delay_cnt <= 0; if((wr_flag ==1)&&(rd_flag == 0)) begin state <= WR_DATA_1 ; num <= 7; end else if((wr_flag ==0)&&(rd_flag == 1)) begin state <= START_1 ; rd_restart_flag <= 1; dir_sda_flag <= 1; end else begin state <= IDLE ; end end else begin state <= state ; delay_cnt <= delay_cnt + 1; end end WR_DATA_1 : begin ee_sclk_reg <= 0; num <= 7 ; if(delay_cnt == 3) dir_sda_flag <= 1; else dir_sda_flag <= dir_sda_flag; if(delay_cnt == 1) rd_wrdata_flag <= 1; else rd_wrdata_flag <= 0; if(delay_cnt == 5) begin delay_cnt <= 0 ; state <= state + 1; data_reg <= wr_data; end else begin delay_cnt <= delay_cnt + 1 ; state <= state; end end WR_DATA_2 : begin ee_sclk_reg <= 0; if(delay_cnt == delay>>1) ee_data_reg <= data_reg[num]; else ee_data_reg <= ee_data_reg; if(delay_cnt == delay) begin state <= state + 1; delay_cnt <= 0; end else begin state <= state ; delay_cnt <= delay_cnt + 1; end end WR_DATA_3: begin ee_sclk_reg <= 1; ee_data_reg <= ee_data_reg; if(delay_cnt == delay) begin if(num == 0) begin state <= WR_DATA_ACK1; delay_cnt <= 0; end else begin state <= WR_DATA_2; delay_cnt <= 0; num <= num -1; end end else begin state <= state ; delay_cnt <= delay_cnt + 1; end end WR_DATA_ACK1: begin ee_sclk_reg <= 0; ee_data_reg <= 0; if(delay_cnt == 4) dir_sda_flag <= 0; else dir_sda_flag <= dir_sda_flag; if(delay_cnt == delay) begin state <= state + 1; delay_cnt <= 0; end else begin state <= state ; delay_cnt <= delay_cnt + 1; end end WR_DATA_ACK2: begin ee_sclk_reg <= 1; if(delay_cnt == delay) begin delay_cnt <= 0; dir_sda_flag <= 1; if(wr_data_flag) state <= WR_DATA_1 ; else state <= STOP_1 ; end else begin state <= state ; delay_cnt <= delay_cnt + 1; end end RD_DATA_1: begin //read ee_sclk_reg <= 0; if(delay_cnt == 4) dir_sda_flag <= 0; else dir_sda_flag <= dir_sda_flag; if(delay_cnt == delay>>1) rd_data_reg[num] <= ee_I2C_SDA; else data_reg <= data_reg; if(delay_cnt == delay) begin state <= state + 1; delay_cnt <= 0; end else begin state <= state ; delay_cnt <= delay_cnt + 1; end end RD_DATA_2: begin ee_sclk_reg <= 1; if(delay_cnt == delay) begin if(num == 0) begin state <= state + 1; delay_cnt <= 0; end else begin state <= RD_DATA_1; delay_cnt <= 0; num <= num - 1; end end else begin state <= state ; delay_cnt <= delay_cnt + 1; end end RD_DATA_ACK1: begin //read data from slave, Notice: the ACK send from Master. ee_sclk_reg <= 0; if(delay_cnt == 4) dir_sda_flag <= 1; else dir_sda_flag <= dir_sda_flag; if(rd_data_flag) ee_data_reg <= 0; //if have data need to read, Master must PULL DOWN the SDA else ee_data_reg <= 1; if(delay_cnt == delay) begin state <= state + 1; delay_cnt <= 0; end else begin state <= state ; delay_cnt <= delay_cnt + 1; end end RD_DATA_ACK2 : begin ee_sclk_reg <= 1; if(delay_cnt == 2) wr_rddata_flag <= 1; else wr_rddata_flag <= 0; if(delay_cnt == delay) begin delay_cnt <= 0; if(rd_data_flag) begin state <= RD_DATA_1 ; num <= 7; end else begin state <= STOP_1 ; num <= 0; end end else begin state <= state ; delay_cnt <= delay_cnt + 1; end end STOP_1: begin ee_sclk_reg <= 0; ee_data_reg <= 0; if(delay_cnt == delay) begin state <= state + 1; delay_cnt <= 0; end else begin state <= state ; delay_cnt <= delay_cnt + 1; end end STOP_2: begin ee_sclk_reg <= 1; ee_data_reg <= 0; if(delay_cnt == delay) begin state <= state + 1; delay_cnt <= 0; end else begin state <= state ; delay_cnt <= delay_cnt + 1; end end STOP_3: begin ee_sclk_reg <= 1; ee_data_reg <= 1; if(delay_cnt == delay) begin if(wr_flag == 1) begin state <= state + 1; delay_cnt <= 0; end else begin //read，not need wait. rd_flag <= 0; state <= IDLE; delay_cnt <= 0; end end else begin state <= state ; delay_cnt <= delay_cnt + 1; end end WRITE_TIME: begin //if write, need wait a lot time to re-satrt.if read, not need wait. wr_flag <= 0; if(delay_cnt == delay_10ms) begin state <= IDLE; delay_cnt <= 0; end else begin state <= state ; delay_cnt <= delay_cnt + 1; end end default: state <= IDLE; endcase end end //---------------------------------- assign ee_I2C_CLK = ee_sclk_reg; assign ee_I2C_SDA = dir_sda_flag ? ee_data_reg: 1'bz; assign rd_wrdata_en = rd_wrdata_flag; assign wr_rddata_en = wr_rddata_flag; assign rd_data = rd_data_reg; endmodule // megafunction wizard: %FIFO%// GENERATION: STANDARD// VERSION: WM1.0// MODULE: scfifo // ============================================================// File Name: RD_DATA_BUF.v// Megafunction Name(s):// scfifo//// Simulation Library Files(s):// altera_mf// ============================================================// ************************************************************// THIS IS A WIZARD-GENERATED FILE. DO NOT EDIT THIS FILE!//// 16.0.0 Build 211 04/27/2016 SJ Standard Edition// ************************************************************//Copyright (C) 1991-2016 Altera Corporation. All rights reserved.//Your use of Altera Corporation's design tools, logic functions //and other software and tools, and its AMPP partner logic //functions, and any output files from any of the foregoing //(including device programming or simulation files), and any //associated documentation or information are expressly subject //to the terms and conditions of the Altera Program License //Subscription Agreement, the Altera Quartus Prime License Agreement,//the Altera MegaCore Function License Agreement, or other //applicable license agreement, including, without limitation, //that your use is for the sole purpose of programming logic //devices manufactured by Altera and sold by Altera or its //authorized distributors. Please refer to the applicable //agreement for further details.// synopsys translate_off`timescale 1 ps / 1 ps// synopsys translate_onmodule RD_DATA_BUF ( aclr, clock, data, rdreq, wrreq, empty, full, q, usedw); input aclr; input clock; input [7:0] data; input rdreq; input wrreq; output empty; output full; output [7:0] q; output [4:0] usedw; wire sub_wire0; wire sub_wire1; wire [7:0] sub_wire2; wire [4:0] sub_wire3; wire empty = sub_wire0; wire full = sub_wire1; wire [7:0] q = sub_wire2[7:0]; wire [4:0] usedw = sub_wire3[4:0]; scfifo scfifo_component ( .aclr (aclr), .clock (clock), .data (data), .rdreq (rdreq), .wrreq (wrreq), .empty (sub_wire0), .full (sub_wire1), .q (sub_wire2), .usedw (sub_wire3), .almost_empty (), .almost_full (), .eccstatus (), .sclr ()); defparam scfifo_component.add_ram_output_register = "OFF", scfifo_component.intended_device_family = "Cyclone IV E", scfifo_component.lpm_numwords = 32, scfifo_component.lpm_showahead = "OFF", scfifo_component.lpm_type = "scfifo", scfifo_component.lpm_width = 8, scfifo_component.lpm_widthu = 5, scfifo_component.overflow_checking = "ON", scfifo_component.underflow_checking = "ON", scfifo_component.use_eab = "ON";endmodule// ============================================================// CNX file retrieval info// ============================================================// Retrieval info: PRIVATE: AlmostEmpty NUMERIC "0"// Retrieval info: PRIVATE: AlmostEmptyThr NUMERIC "-1"// Retrieval info: PRIVATE: AlmostFull NUMERIC "0"// Retrieval info: PRIVATE: AlmostFullThr NUMERIC "-1"// Retrieval info: PRIVATE: CLOCKS_ARE_SYNCHRONIZED NUMERIC "1"// Retrieval info: PRIVATE: Clock NUMERIC "0"// Retrieval info: PRIVATE: Depth NUMERIC "32"// Retrieval info: PRIVATE: Empty NUMERIC "1"// Retrieval info: PRIVATE: Full NUMERIC "1"// Retrieval info: PRIVATE: INTENDED_DEVICE_FAMILY STRING "Cyclone IV E"// Retrieval info: PRIVATE: LE_BasedFIFO NUMERIC "0"// Retrieval info: PRIVATE: LegacyRREQ NUMERIC "1"// Retrieval info: PRIVATE: MAX_DEPTH_BY_9 NUMERIC "0"// Retrieval info: PRIVATE: OVERFLOW_CHECKING NUMERIC "0"// Retrieval info: PRIVATE: Optimize NUMERIC "2"// Retrieval info: PRIVATE: RAM_BLOCK_TYPE NUMERIC "0"// Retrieval info: PRIVATE: SYNTH_WRAPPER_GEN_POSTFIX STRING "0"// Retrieval info: PRIVATE: UNDERFLOW_CHECKING NUMERIC "0"// Retrieval info: PRIVATE: UsedW NUMERIC "1"// Retrieval info: PRIVATE: Width NUMERIC "8"// Retrieval info: PRIVATE: dc_aclr NUMERIC "0"// Retrieval info: PRIVATE: diff_widths NUMERIC "0"// Retrieval info: PRIVATE: msb_usedw NUMERIC "0"// Retrieval info: PRIVATE: output_width NUMERIC "8"// Retrieval info: PRIVATE: rsEmpty NUMERIC "1"// Retrieval info: PRIVATE: rsFull NUMERIC "0"// Retrieval info: PRIVATE: rsUsedW NUMERIC "0"// Retrieval info: PRIVATE: sc_aclr NUMERIC "1"// Retrieval info: PRIVATE: sc_sclr NUMERIC "0"// Retrieval info: PRIVATE: wsEmpty NUMERIC "0"// Retrieval info: PRIVATE: wsFull NUMERIC "1"// Retrieval info: PRIVATE: wsUsedW NUMERIC "0"// Retrieval info: LIBRARY: altera_mf altera_mf.altera_mf_components.all// Retrieval info: CONSTANT: ADD_RAM_OUTPUT_REGISTER STRING "OFF"// Retrieval info: CONSTANT: INTENDED_DEVICE_FAMILY STRING "Cyclone IV E"// Retrieval info: CONSTANT: LPM_NUMWORDS NUMERIC "32"// Retrieval info: CONSTANT: LPM_SHOWAHEAD STRING "OFF"// Retrieval info: CONSTANT: LPM_TYPE STRING "scfifo"// Retrieval info: CONSTANT: LPM_WIDTH NUMERIC "8"// Retrieval info: CONSTANT: LPM_WIDTHU NUMERIC "5"// Retrieval info: CONSTANT: OVERFLOW_CHECKING STRING "ON"// Retrieval info: CONSTANT: UNDERFLOW_CHECKING STRING "ON"// Retrieval info: CONSTANT: USE_EAB STRING "ON"// Retrieval info: USED_PORT: aclr 0 0 0 0 INPUT NODEFVAL "aclr"// Retrieval info: USED_PORT: clock 0 0 0 0 INPUT NODEFVAL "clock"// Retrieval info: USED_PORT: data 0 0 8 0 INPUT NODEFVAL "data[7..0]"// Retrieval info: USED_PORT: empty 0 0 0 0 OUTPUT NODEFVAL "empty"// Retrieval info: USED_PORT: full 0 0 0 0 OUTPUT NODEFVAL "full"// Retrieval info: USED_PORT: q 0 0 8 0 OUTPUT NODEFVAL "q[7..0]"// Retrieval info: USED_PORT: rdreq 0 0 0 0 INPUT NODEFVAL "rdreq"// Retrieval info: USED_PORT: usedw 0 0 5 0 OUTPUT NODEFVAL "usedw[4..0]"// Retrieval info: USED_PORT: wrreq 0 0 0 0 INPUT NODEFVAL "wrreq"// Retrieval info: CONNECT: @aclr 0 0 0 0 aclr 0 0 0 0// Retrieval info: CONNECT: @clock 0 0 0 0 clock 0 0 0 0// Retrieval info: CONNECT: @data 0 0 8 0 data 0 0 8 0// Retrieval info: CONNECT: @rdreq 0 0 0 0 rdreq 0 0 0 0// Retrieval info: CONNECT: @wrreq 0 0 0 0 wrreq 0 0 0 0// Retrieval info: CONNECT: empty 0 0 0 0 @empty 0 0 0 0// Retrieval info: CONNECT: full 0 0 0 0 @full 0 0 0 0// Retrieval info: CONNECT: q 0 0 8 0 @q 0 0 8 0// Retrieval info: CONNECT: usedw 0 0 5 0 @usedw 0 0 5 0// Retrieval info: GEN_FILE: TYPE_NORMAL RD_DATA_BUF.v TRUE// Retrieval info: GEN_FILE: TYPE_NORMAL RD_DATA_BUF.inc FALSE// Retrieval info: GEN_FILE: TYPE_NORMAL RD_DATA_BUF.cmp FALSE// Retrieval info: GEN_FILE: TYPE_NORMAL RD_DATA_BUF.bsf FALSE// Retrieval info: GEN_FILE: TYPE_NORMAL RD_DATA_BUF_inst.v FALSE// Retrieval info: GEN_FILE: TYPE_NORMAL RD_DATA_BUF_bb.v TRUE// Retrieval info: LIB_FILE: altera_mf
TB:
`timescale 1 ps/1 ps module EEPROM_TB; reg clk; reg rst_n; wire ee_I2C_CLK; wire ee_I2C_SDA; EEPROM u_EEPROM( .clk(clk), .rst_n(rst_n), .EEPROM_SCK(ee_I2C_CLK), .EEPROM_SDA(ee_I2C_SDA) ); parameter T = 20000; always #(T/2) clk = ~clk; initial begin clk = 0; rst_n = 0; $stop; #(500*T) rst_n = 1; end endmodule