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SDRAM单字节读写仿真测试

仿真测试的所有文件

SDRAM单字节读写仿真测试

 modelsim仿真

初始化时序

初始化状态机

SDRAM单字节读写仿真测试
SDRAM单字节读写仿真测试

去掉多数信号可以看到初始化时序 

SDRAM单字节读写仿真测试

PRE预充电经过两个周期进入AREF自刷新,自刷新需进行两次,然后进入MREF模式设置,模式设置经过两个周期跳到IDLE

我这里是以100M的时钟给延迟时间,所以各个周期取值都做得比较大

SDRAM单字节读写仿真测试

单字节读写,写一个读一个

SDRAM单字节读写仿真测试

单字节写命令

先发一个ACT写激活命令经过四个周期进入WR写命令,然后经过四个周期进入PRE预充电命令,预充电延迟两个周期进入IDLE,这里周期取得比较长,可以根据自己需要进行压缩

单字节写状态机

SDRAM单字节读写仿真测试
SDRAM单字节读写仿真测试

单字节读命令

先发一个ACT命令经过四个周期进入RD读命令,然后经过四个周期进入DATA读取数据,最后发出PRE预充电

单字节读状态机

SDRAM单字节读写仿真测试
SDRAM单字节读写仿真测试

下图主要是写请求信号,读请求信号以及写数据标志信号和读数据标志信号

注意写数据标志信号和读数据标志信号都提前了一个周期,主要是我们读数据和写数据都是使用非阻塞赋值

SDRAM单字节读写仿真测试
SDRAM单字节读写仿真测试

自动刷新

自动刷新直接给AREF自动刷新命令,一般取63ns,这里取7个周期

SDRAM单字节读写仿真测试
SDRAM单字节读写仿真测试

在 modelsim中使用命令行来看状态

写一次,读一次

SDRAM单字节读写仿真测试

将data_test模块里的测试长度改为5,然后连续读写5次

SDRAM单字节读写仿真测试
SDRAM单字节读写仿真测试

 下面是所有的仿真文件代码

module sdram_init(
	input					i_clk,//时钟
	input 					i_rst_n,//复位低有效
	input		[15:0]		current_state,//状态
	
	output	reg				refresh_req,//自刷新请求
	output					cnt_200us_flag,//初始化200us完成标志信号
	input					flag_init_end//初始化完成信号
	
	
);

parameter  Areflash   = 16'b0000000000001000;//自动刷新

reg	[14:0]		cnt_200us;
reg	[9:0]		refresh_cnt;


assign	cnt_200us_flag	=	(cnt_200us == 15'd20000)? 1'b1:1'b0;

//计数200us
[email protected](posedge i_clk or negedge i_rst_n)begin
			if(i_rst_n == 1'b0)
				cnt_200us	<=	15'd0;
			else if(cnt_200us < 15'd20000)//20000
				cnt_200us	<=	cnt_200us	+	1'b1;
			else
				cnt_200us	<=	cnt_200us;
end

//自动刷新计数
[email protected](posedge i_clk or negedge i_rst_n)begin
			if(i_rst_n == 1'b0)
				refresh_cnt	<=	10'd0;			
			else if(refresh_cnt == 10'd769)
				refresh_cnt	<=	10'd0;
			else if(flag_init_end)	
				refresh_cnt	<=	refresh_cnt	+	1'b1;
			else
				refresh_cnt	<=	refresh_cnt;
end	

//自动刷新请求
[email protected](posedge i_clk or negedge i_rst_n)begin
			if(i_rst_n == 1'b0)
				refresh_req	<=	1'b0;
			else if(current_state == Areflash)
				refresh_req	<=	1'b0;	
			else if(refresh_cnt == 10'd769)
				refresh_req	<=	1'b1;
			else	
				refresh_req	<=	refresh_req;			
end


endmodule



           
/***************************************************************************************
作者:	李晟
2003-08-27	V0.1	李晟 
 
 添加内存模块倒空功能,在外部需要创建事件:sdram_r ,本SDRAM的内容将会按Bank 顺序damp out 至文件
 sdram_data.txt 中
×××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××××*/
//2004-03-04	陈乃奎	修改原程序中将BANK的数据转存入TXT文件的格式
//2004-03-16	陈乃奎	修改SDRAM 的初始化数据
//2004/04/06	陈乃奎	将SDRAM的操作命令以字符形式表示,以便用MODELSIM监视
//2004/04/19	陈乃奎	修改参数 parameter tAC  =   8;
//2010/09/17	罗瑶	修改sdram的大小,数据位宽,dqm宽度;
/****************************************************************************************
*
*    File Name:  sdram_model.V  
*      Version:  0.0f
*         Date:  July 8th, 1999
*        Model:  BUS Functional
*    Simulator:  Model Technology (PC version 5.2e PE)
*
* Dependencies:  None
*
*       Author:  Son P. Huynh
*        Email:  [email protected]
*        Phone:  (208) 368-3825
*      Company:  Micron Technology, Inc.
*        Model:  sdram_model (1Meg x 16 x 4 Banks)
*
*  Description:  64Mb SDRAM Verilog model
*
*   Limitation:  - Doesn't check for 4096 cycle refresh
*
*         Note:  - Set simulator resolution to "ps" accuracy
*                - Set Debug = 0 to disable $display messages
*
*   Disclaimer:  THESE DESIGNS ARE PROVIDED "AS IS" WITH NO WARRANTY 
*                WHATSOEVER AND MICRON SPECIFICALLY DISCLAIMS ANY 
*                IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR
*                A PARTICULAR PURPOSE, OR AGAINST INFRINGEMENT.
*
*                Copyright ?1998 Micron Semiconductor Products, Inc.
*                All rights researved
*
* Rev   Author          Phone         Date        Changes
* ----  ----------------------------  ----------  ---------------------------------------
* 0.0f  Son Huynh       208-368-3825  07/08/1999  - Fix tWR = 1 Clk + 7.5 ns (Auto)
*       Micron Technology Inc.                    - Fix tWR = 15 ns (Manual)
*                                                 - Fix tRP (Autoprecharge to AutoRefresh)
*
* 0.0a  Son Huynh       208-368-3825  05/13/1998  - First Release (from 64Mb rev 0.0e)
*       Micron Technology Inc.
****************************************************************************************/

`timescale 1ns / 100ps

module sdram_model_plus (Dq, Addr, Ba, Clk, Cke, Cs_n, Ras_n, Cas_n, We_n, Dqm,Debug);

    parameter addr_bits =	13;
    parameter data_bits = 	16;
    parameter col_bits  =	9;
    parameter mem_sizes =	2*1024-1;//1 Meg 

    inout     [data_bits - 1 : 0] Dq;
    input     [addr_bits - 1 : 0] Addr;
    input                 [1 : 0] Ba;
    input                         Clk;
    input                         Cke;
    input                         Cs_n;
    input                         Ras_n;
    input                         Cas_n;
    input                         We_n;
    input                 [3 : 0] Dqm;          //高低各8bit
    //added by xzli
    input			  Debug;

    reg       [data_bits - 1 : 0] Bank0 [0 : mem_sizes];//存储器类型数据
    reg       [data_bits - 1 : 0] Bank1 [0 : mem_sizes];
    reg       [data_bits - 1 : 0] Bank2 [0 : mem_sizes];
    reg       [data_bits - 1 : 0] Bank3 [0 : mem_sizes];

    reg                   [1 : 0] Bank_addr [0 : 3];                // Bank Address Pipeline
    reg        [col_bits - 1 : 0] Col_addr [0 : 3];                 // Column Address Pipeline
    reg                   [3 : 0] Command [0 : 3];                  // Command Operation Pipeline
    reg                   [3 : 0] Dqm_reg0, Dqm_reg1;               // DQM Operation Pipeline
    reg       [addr_bits - 1 : 0] B0_row_addr, B1_row_addr, B2_row_addr, B3_row_addr;

    reg       [addr_bits - 1 : 0] Mode_reg;
    reg       [data_bits - 1 : 0] Dq_reg, Dq_dqm;
    reg       [col_bits - 1 : 0] Col_temp, Burst_counter;

    reg                           Act_b0, Act_b1, Act_b2, Act_b3;   // Bank Activate
    reg                           Pc_b0, Pc_b1, Pc_b2, Pc_b3;       // Bank Precharge

    reg                   [1 : 0] Bank_precharge     [0 : 3];       // Precharge Command
    reg                           A10_precharge      [0 : 3];       // Addr[10] = 1 (All banks)
    reg                           Auto_precharge     [0 : 3];       // RW AutoPrecharge (Bank)
    reg                           Read_precharge     [0 : 3];       // R  AutoPrecharge
    reg                           Write_precharge    [0 : 3];       //  W AutoPrecharge
    integer                       Count_precharge    [0 : 3];       // RW AutoPrecharge (Counter)
    reg                           RW_interrupt_read  [0 : 3];       // RW Interrupt Read with Auto Precharge
    reg                           RW_interrupt_write [0 : 3];       // RW Interrupt Write with Auto Precharge

    reg                           Data_in_enable;
    reg                           Data_out_enable;

    reg                   [1 : 0] Bank, Previous_bank;
    reg       [addr_bits - 1 : 0] Row;
    reg        [col_bits - 1 : 0] Col, Col_brst;

    // Internal system clock
    reg                           CkeZ, Sys_clk;

    reg	[21:0]	dd;
    
    // Commands Decode
    wire      Active_enable    = ~Cs_n & ~Ras_n &  Cas_n &  We_n;
    wire      Aref_enable      = ~Cs_n & ~Ras_n & ~Cas_n &  We_n;
    wire      Burst_term       = ~Cs_n &  Ras_n &  Cas_n & ~We_n;
    wire      Mode_reg_enable  = ~Cs_n & ~Ras_n & ~Cas_n & ~We_n;
    wire      Prech_enable     = ~Cs_n & ~Ras_n &  Cas_n & ~We_n;
    wire      Read_enable      = ~Cs_n &  Ras_n & ~Cas_n &  We_n;
    wire      Write_enable     = ~Cs_n &  Ras_n & ~Cas_n & ~We_n;

    // Burst Length Decode
    wire      Burst_length_1   = ~Mode_reg[2] & ~Mode_reg[1] & ~Mode_reg[0];
    wire      Burst_length_2   = ~Mode_reg[2] & ~Mode_reg[1] &  Mode_reg[0];
    wire      Burst_length_4   = ~Mode_reg[2] &  Mode_reg[1] & ~Mode_reg[0];
    wire      Burst_length_8   = ~Mode_reg[2] &  Mode_reg[1] &  Mode_reg[0];

    // CAS Latency Decode
    wire      Cas_latency_2    = ~Mode_reg[6] &  Mode_reg[5] & ~Mode_reg[4];
    wire      Cas_latency_3    = ~Mode_reg[6] &  Mode_reg[5] &  Mode_reg[4];

    // Write Burst Mode
    wire      Write_burst_mode = Mode_reg[9];

    wire      Debug;		// Debug messages : 1 = On; 0 = Off
    wire      Dq_chk           = Sys_clk & Data_in_enable;      // Check setup/hold time for DQ

    reg		[31:0]	mem_d;
    
    event	sdram_r,sdram_w,compare;
    
    
   
   
    assign    Dq               = Dq_reg;                        // DQ buffer

    // Commands Operation
    `define   ACT       0
    `define   NOP       1
    `define   READ      2
    `define   READ_A    3
    `define   WRITE     4
    `define   WRITE_A   5
    `define   PRECH     6
    `define   A_REF     7
    `define   BST       8
    `define   LMR       9

//    // Timing Parameters for -75 (PC133) and CAS Latency = 2
//    parameter tAC  =   8;	//test 6.5
//    parameter tHZ  =   7.0;
//    parameter tOH  =   2.7;
//    parameter tMRD =   2.0;     // 2 Clk Cycles
//    parameter tRAS =  44.0;
//    parameter tRC  =  66.0;
//    parameter tRCD =  20.0;
//    parameter tRP  =  20.0;
//    parameter tRRD =  15.0;
//    parameter tWRa =   7.5;     // A2 Version - Auto precharge mode only (1 Clk + 7.5 ns)
//    parameter tWRp =  0.0;     // A2 Version - Precharge mode only (15 ns)

    // Timing Parameters for -7 (PC143) and CAS Latency = 3
    parameter tAC  =   6.5;	//test 6.5
    parameter tHZ  =   5.5;
    parameter tOH  =   2;
    parameter tMRD =   2.0;     // 2 Clk Cycles
    parameter tRAS =  48.0;
    parameter tRC  =  70.0;
    parameter tRCD =  20.0;
    parameter tRP  =  20.0;
    parameter tRRD =  14.0;
    parameter tWRa =   7.5;     // A2 Version - Auto precharge mode only (1 Clk + 7.5 ns)
    parameter tWRp =  0.0;     // A2 Version - Precharge mode only (15 ns)
    
    // Timing Check variable
    integer   MRD_chk;
    integer   WR_counter [0 : 3];
    time      WR_chk [0 : 3];
    time      RC_chk, RRD_chk;
    time      RAS_chk0, RAS_chk1, RAS_chk2, RAS_chk3;
    time      RCD_chk0, RCD_chk1, RCD_chk2, RCD_chk3;
    time      RP_chk0, RP_chk1, RP_chk2, RP_chk3;

    integer	test_file;
    
    //*****display the command of the sdram**************************************
    
    parameter	Mode_Reg_Set	=4'b0000;
    parameter	Auto_Refresh	=4'b0001;
    parameter	Row_Active	=4'b0011;
    parameter	Pre_Charge	=4'b0010;
    parameter	PreCharge_All	=4'b0010;
    parameter	Write		=4'b0100;
    parameter	Write_Pre	=4'b0100;
    parameter	Read		=4'b0101;
    parameter	Read_Pre	=4'b0101;
    parameter	Burst_Stop	=4'b0110;
    parameter	Nop		=4'b0111;
    parameter	Dsel		=4'b1111;

    wire	[3:0]	sdram_control;
    reg			cke_temp;
    reg		[8*13:1]	sdram_command;
   
    [email protected](posedge Clk)
	cke_temp<=Cke;

    assign	sdram_control={Cs_n,Ras_n,Cas_n,We_n};

    [email protected](sdram_control or cke_temp)
	begin
		case(sdram_control)
			Mode_Reg_Set:	sdram_command<="Mode_Reg_Set";
			Auto_Refresh:	sdram_command<="Auto_Refresh";
			Row_Active:	sdram_command<="Row_Active";
			Pre_Charge:	sdram_command<="Pre_Charge";
			Burst_Stop:	sdram_command<="Burst_Stop";
			Dsel:		sdram_command<="Dsel";

			Write:		if(cke_temp==1)
						sdram_command<="Write";
					else
						sdram_command<="Write_suspend";
						
			Read:		if(cke_temp==1)
						sdram_command<="Read";
					else
						sdram_command<="Read_suspend";
						
			Nop:		if(cke_temp==1)
						sdram_command<="Nop";
					else
						sdram_command<="Self_refresh";
						
			default:	sdram_command<="Power_down";
		endcase
	end

    //*****************************************************
    
    initial 
    	begin
		//test_file=$fopen("test_file.txt");
	end

    initial 
    	begin
        Dq_reg = {data_bits{1'bz}};
        {Data_in_enable, Data_out_enable} = 0;
        {Act_b0, Act_b1, Act_b2, Act_b3} = 4'b0000;
        {Pc_b0, Pc_b1, Pc_b2, Pc_b3} = 4'b0000;
        {WR_chk[0], WR_chk[1], WR_chk[2], WR_chk[3]} = 0;
        {WR_counter[0], WR_counter[1], WR_counter[2], WR_counter[3]} = 0;
        {RW_interrupt_read[0], RW_interrupt_read[1], RW_interrupt_read[2], RW_interrupt_read[3]} = 0;
        {RW_interrupt_write[0], RW_interrupt_write[1], RW_interrupt_write[2], RW_interrupt_write[3]} = 0;
        {MRD_chk, RC_chk, RRD_chk} = 0;
        {RAS_chk0, RAS_chk1, RAS_chk2, RAS_chk3} = 0;
        {RCD_chk0, RCD_chk1, RCD_chk2, RCD_chk3} = 0;
        {RP_chk0, RP_chk1, RP_chk2, RP_chk3} = 0;
        $timeformat (-9, 0, " ns", 12);
        //$readmemh("bank0.txt", Bank0);
        //$readmemh("bank1.txt", Bank1);
        //$readmemh("bank2.txt", Bank2);
        //$readmemh("bank3.txt", Bank3);
/*  	
  	 for(dd=0;dd<=mem_sizes;dd=dd+1)
        	begin
        		Bank0[dd]=dd[data_bits - 1 : 0];
        		Bank1[dd]=dd[data_bits - 1 : 0]+1;
        		Bank2[dd]=dd[data_bits - 1 : 0]+2;
        		Bank3[dd]=dd[data_bits - 1 : 0]+3;
        	end
*/        	
  	initial_sdram(0);
  	end
 
        task	initial_sdram; 
 
 		input		data_sign;
 		reg	[3:0]	data_sign;
 	     
       		for(dd=0;dd<=mem_sizes;dd=dd+1)
        	begin
        		mem_d = {data_sign,data_sign,data_sign,data_sign,data_sign,data_sign,data_sign,data_sign};
        		if(data_bits==16)
        			begin
        				Bank0[dd]=mem_d[15:0];
        				Bank1[dd]=mem_d[15:0];
        				Bank2[dd]=mem_d[15:0];
        				Bank3[dd]=mem_d[15:0];
        			end
        		else if(data_bits==32)
        			begin
        				Bank0[dd]=mem_d[31:0];
        				Bank1[dd]=mem_d[31:0];
        				Bank2[dd]=mem_d[31:0];
        				Bank3[dd]=mem_d[31:0];
        			end
        	end	
      	
       		endtask

    // System clock generator
    always
    	begin
       		@(posedge Clk)
       			begin
            			Sys_clk = CkeZ;
            			CkeZ = Cke;
        		end
        	@(negedge Clk) 
        		begin
            			Sys_clk = 1'b0;
        		end
    	end

    always @ (posedge Sys_clk) begin
        // Internal Commamd Pipelined
        Command[0] = Command[1];
        Command[1] = Command[2];
        Command[2] = Command[3];
        Command[3] = `NOP;

        Col_addr[0] = Col_addr[1];
        Col_addr[1] = Col_addr[2];
        Col_addr[2] = Col_addr[3];
        Col_addr[3] = {col_bits{1'b0}};

        Bank_addr[0] = Bank_addr[1];
        Bank_addr[1] = Bank_addr[2];
        Bank_addr[2] = Bank_addr[3];
        Bank_addr[3] = 2'b0;

        Bank_precharge[0] = Bank_precharge[1];
        Bank_precharge[1] = Bank_precharge[2];
        Bank_precharge[2] = Bank_precharge[3];
        Bank_precharge[3] = 2'b0;

        A10_precharge[0] = A10_precharge[1];
        A10_precharge[1] = A10_precharge[2];
        A10_precharge[2] = A10_precharge[3];
        A10_precharge[3] = 1'b0;

        // Dqm pipeline for Read
        Dqm_reg0 = Dqm_reg1;
        Dqm_reg1 = Dqm;

        // Read or Write with Auto Precharge Counter
        if (Auto_precharge[0] == 1'b1) begin
            Count_precharge[0] = Count_precharge[0] + 1;
        end
        if (Auto_precharge[1] == 1'b1) begin
            Count_precharge[1] = Count_precharge[1] + 1;
        end
        if (Auto_precharge[2] == 1'b1) begin
            Count_precharge[2] = Count_precharge[2] + 1;
        end
        if (Auto_precharge[3] == 1'b1) begin
            Count_precharge[3] = Count_precharge[3] + 1;
        end

        // tMRD Counter
        MRD_chk = MRD_chk + 1;

        // tWR Counter for Write
        WR_counter[0] = WR_counter[0] + 1;
        WR_counter[1] = WR_counter[1] + 1;
        WR_counter[2] = WR_counter[2] + 1;
        WR_counter[3] = WR_counter[3] + 1;

        // Auto Refresh
        if (Aref_enable == 1'b1) begin
            if (Debug) $display ("at time %t AREF : Auto Refresh", $time);
            // Auto Refresh to Auto Refresh
            if (($time - RC_chk < tRC)&&Debug) begin
                $display ("at time %t ERROR: tRC violation during Auto Refresh", $time);
            end
            // Precharge to Auto Refresh
            if (($time - RP_chk0 < tRP || $time - RP_chk1 < tRP || $time - RP_chk2 < tRP || $time - RP_chk3 < tRP)&&Debug) begin
                $display ("at time %t ERROR: tRP violation during Auto Refresh", $time);
            end
            // Precharge to Refresh
            if (Pc_b0 == 1'b0 || Pc_b1 == 1'b0 || Pc_b2 == 1'b0 || Pc_b3 == 1'b0) begin
                $display ("at time %t ERROR: All banks must be Precharge before Auto Refresh", $time);
            end
            // Record Current tRC time
            RC_chk = $time;
        end
        
        // Load Mode Register
        if (Mode_reg_enable == 1'b1) begin
            // Decode CAS Latency, Burst Length, Burst Type, and Write Burst Mode
            if (Pc_b0 == 1'b1 && Pc_b1 == 1'b1 && Pc_b2 == 1'b1 && Pc_b3 == 1'b1) begin
                Mode_reg = Addr;
                if (Debug) begin
                    $display ("at time %t LMR  : Load Mode Register", $time);
                    // CAS Latency
                    if (Addr[6 : 4] == 3'b010)
                        $display ("                            CAS Latency      = 2");
                    else if (Addr[6 : 4] == 3'b011)
                        $display ("                            CAS Latency      = 3");
                    else
                        $display ("                            CAS Latency      = Reserved");
                    // Burst Length
                    if (Addr[2 : 0] == 3'b000)
                        $display ("                            Burst Length     = 1");
                    else if (Addr[2 : 0] == 3'b001)
                        $display ("                            Burst Length     = 2");
                    else if (Addr[2 : 0] == 3'b010)
                        $display ("                            Burst Length     = 4");
                    else if (Addr[2 : 0] == 3'b011)
                        $display ("                            Burst Length     = 8");
                    else if (Addr[3 : 0] == 4'b0111)
                        $display ("                            Burst Length     = Full");
                    else
                        $display ("                            Burst Length     = Reserved");
                    // Burst Type
                    if (Addr[3] == 1'b0)
                        $display ("                            Burst Type       = Sequential");
                    else if (Addr[3] == 1'b1)
                        $display ("                            Burst Type       = Interleaved");
                    else
                        $display ("                            Burst Type       = Reserved");
                    // Write Burst Mode
                    if (Addr[9] == 1'b0)
                        $display ("                            Write Burst Mode = Programmed Burst Length");
                    else if (Addr[9] == 1'b1)
                        $display ("                            Write Burst Mode = Single Location Access");
                    else
                        $display ("                            Write Burst Mode = Reserved");
                end
            end else begin
                $display ("at time %t ERROR: all banks must be Precharge before Load Mode Register", $time);
            end
            // REF to LMR
            if ($time - RC_chk < tRC) begin
                $display ("at time %t ERROR: tRC violation during Load Mode Register", $time);
            end
            // LMR to LMR
            if (MRD_chk < tMRD) begin
                $display ("at time %t ERROR: tMRD violation during Load Mode Register", $time);
            end
            MRD_chk = 0;
        end
        
        // Active Block (Latch Bank Address and Row Address)
        if (Active_enable == 1'b1) begin
            if (Ba == 2'b00 && Pc_b0 == 1'b1) begin
                {Act_b0, Pc_b0} = 2'b10;
                B0_row_addr = Addr [addr_bits - 1 : 0];
                RCD_chk0 = $time;
                RAS_chk0 = $time;
                if (Debug) $display ("at time %t ACT  : Bank = 0 Row = %d", $time, Addr);
                // Precharge to Activate Bank 0
                if ($time - RP_chk0 < tRP) begin
                    $display ("at time %t ERROR: tRP violation during Activate bank 0", $time);
                end
            end else if (Ba == 2'b01 && Pc_b1 == 1'b1) begin
                {Act_b1, Pc_b1} = 2'b10;
                B1_row_addr = Addr [addr_bits - 1 : 0];
                RCD_chk1 = $time;
                RAS_chk1 = $time;
                if (Debug) $display ("at time %t ACT  : Bank = 1 Row = %d", $time, Addr);
                // Precharge to Activate Bank 1
                if ($time - RP_chk1 < tRP) begin
                    $display ("at time %t ERROR: tRP violation during Activate bank 1", $time);
                end
            end else if (Ba == 2'b10 && Pc_b2 == 1'b1) begin
                {Act_b2, Pc_b2} = 2'b10;
                B2_row_addr = Addr [addr_bits - 1 : 0];
                RCD_chk2 = $time;
                RAS_chk2 = $time;
                if (Debug) $display ("at time %t ACT  : Bank = 2 Row = %d", $time, Addr);
                // Precharge to Activate Bank 2
                if ($time - RP_chk2 < tRP) begin
                    $display ("at time %t ERROR: tRP violation during Activate bank 2", $time);
                end
            end else if (Ba == 2'b11 && Pc_b3 == 1'b1) begin
                {Act_b3, Pc_b3} = 2'b10;
                B3_row_addr = Addr [addr_bits - 1 : 0];
                RCD_chk3 = $time;
                RAS_chk3 = $time;
                if (Debug) $display ("at time %t ACT  : Bank = 3 Row = %d", $time, Addr);
                // Precharge to Activate Bank 3
                if ($time - RP_chk3 < tRP) begin
                    $display ("at time %t ERROR: tRP violation during Activate bank 3", $time);
                end
            end else if (Ba == 2'b00 && Pc_b0 == 1'b0) begin
                $display ("at time %t ERROR: Bank 0 is not Precharged.", $time);
            end else if (Ba == 2'b01 && Pc_b1 == 1'b0) begin
                $display ("at time %t ERROR: Bank 1 is not Precharged.", $time);
            end else if (Ba == 2'b10 && Pc_b2 == 1'b0) begin
                $display ("at time %t ERROR: Bank 2 is not Precharged.", $time);
            end else if (Ba == 2'b11 && Pc_b3 == 1'b0) begin
                $display ("at time %t ERROR: Bank 3 is not Precharged.", $time);
            end
            // Active Bank A to Active Bank B
            if ((Previous_bank != Ba) && ($time - RRD_chk < tRRD)) begin
                $display ("at time %t ERROR: tRRD violation during Activate bank = %d", $time, Ba);
            end
            // Load Mode Register to Active
            if (MRD_chk < tMRD ) begin
                $display ("at time %t ERROR: tMRD violation during Activate bank = %d", $time, Ba);
            end
            // Auto Refresh to Activate
            if (($time - RC_chk < tRC)&&Debug) begin
                $display ("at time %t ERROR: tRC violation during Activate bank = %d", $time, Ba);
            end
            // Record variables for checking violation
            RRD_chk = $time;
            Previous_bank = Ba;
        end
        
        // Precharge Block
        if (Prech_enable == 1'b1) begin
            if (Addr[10] == 1'b1) begin
                {Pc_b0, Pc_b1, Pc_b2, Pc_b3} = 4'b1111;
                {Act_b0, Act_b1, Act_b2, Act_b3} = 4'b0000;
                RP_chk0 = $time;
                RP_chk1 = $time;
                RP_chk2 = $time;
                RP_chk3 = $time;
                if (Debug) $display ("at time %t PRE  : Bank = ALL",$time);
                // Activate to Precharge all banks
                if (($time - RAS_chk0 < tRAS) || ($time - RAS_chk1 < tRAS) ||
                    ($time - RAS_chk2 < tRAS) || ($time - RAS_chk3 < tRAS)) begin
                    $display ("at time %t ERROR: tRAS violation during Precharge all bank", $time);
                end
                // tWR violation check for write
                if (($time - WR_chk[0] < tWRp) || ($time - WR_chk[1] < tWRp) ||
                    ($time - WR_chk[2] < tWRp) || ($time - WR_chk[3] < tWRp)) begin
                    $display ("at time %t ERROR: tWR violation during Precharge all bank", $time);
                end
            end else if (Addr[10] == 1'b0) begin
                if (Ba == 2'b00) begin
                    {Pc_b0, Act_b0} = 2'b10;
                    RP_chk0 = $time;
                    if (Debug) $display ("at time %t PRE  : Bank = 0",$time);
                    // Activate to Precharge Bank 0
                    if ($time - RAS_chk0 < tRAS) begin
                        $display ("at time %t ERROR: tRAS violation during Precharge bank 0", $time);
                    end
                end else if (Ba == 2'b01) begin
                    {Pc_b1, Act_b1} = 2'b10;
                    RP_chk1 = $time;
                    if (Debug) $display ("at time %t PRE  : Bank = 1",$time);
                    // Activate to Precharge Bank 1
                    if ($time - RAS_chk1 < tRAS) begin
                        $display ("at time %t ERROR: tRAS violation during Precharge bank 1", $time);
                    end
                end else if (Ba == 2'b10) begin
                    {Pc_b2, Act_b2} = 2'b10;
                    RP_chk2 = $time;
                    if (Debug) $display ("at time %t PRE  : Bank = 2",$time);
                    // Activate to Precharge Bank 2
                    if ($time - RAS_chk2 < tRAS) begin
                        $display ("at time %t ERROR: tRAS violation during Precharge bank 2", $time);
                    end
                end else if (Ba == 2'b11) begin
                    {Pc_b3, Act_b3} = 2'b10;
                    RP_chk3 = $time;
                    if (Debug) $display ("at time %t PRE  : Bank = 3",$time);
                    // Activate to Precharge Bank 3
                    if ($time - RAS_chk3 < tRAS) begin
                        $display ("at time %t ERROR: tRAS violation during Precharge bank 3", $time);
                    end
                end
                // tWR violation check for write
                if ($time - WR_chk[Ba] < tWRp) begin
                    $display ("at time %t ERROR: tWR violation during Precharge bank %d", $time, Ba);
                end
            end
            // Terminate a Write Immediately (if same bank or all banks)
            if (Data_in_enable == 1'b1 && (Bank == Ba || Addr[10] == 1'b1)) begin
                Data_in_enable = 1'b0;
            end
            // Precharge Command Pipeline for Read
            if (Cas_latency_3 == 1'b1) begin
                Command[2] = `PRECH;
                Bank_precharge[2] = Ba;
                A10_precharge[2] = Addr[10];
            end else if (Cas_latency_2 == 1'b1) begin
                Command[1] = `PRECH;
                Bank_precharge[1] = Ba;
                A10_precharge[1] = Addr[10];
            end
        end
        
        // Burst terminate
        if (Burst_term == 1'b1) begin
            // Terminate a Write Immediately
            if (Data_in_enable == 1'b1) begin
                Data_in_enable = 1'b0;
            end
            // Terminate a Read Depend on CAS Latency
            if (Cas_latency_3 == 1'b1) begin
                Command[2] = `BST;
            end else if (Cas_latency_2 == 1'b1) begin
                Command[1] = `BST;
            end
            if (Debug) $display ("at time %t BST  : Burst Terminate",$time);
        end
        
        // Read, Write, Column Latch
        if (Read_enable == 1'b1 || Write_enable == 1'b1) begin
            // Check to see if bank is open (ACT)
            if ((Ba == 2'b00 && Pc_b0 == 1'b1) || (Ba == 2'b01 && Pc_b1 == 1'b1) ||
                (Ba == 2'b10 && Pc_b2 == 1'b1) || (Ba == 2'b11 && Pc_b3 == 1'b1)) begin
                $display("at time %t ERROR: Cannot Read or Write - Bank %d is not Activated", $time, Ba);
            end
            // Activate to Read or Write
            if ((Ba == 2'b00) && ($time - RCD_chk0 < tRCD))
                $display("at time %t ERROR: tRCD violation during Read or Write to Bank 0", $time);
            if ((Ba == 2'b01) && ($time - RCD_chk1 < tRCD))
                $display("at time %t ERROR: tRCD violation during Read or Write to Bank 1", $time);
            if ((Ba == 2'b10) && ($time - RCD_chk2 < tRCD))
                $display("at time %t ERROR: tRCD violation during Read or Write to Bank 2", $time);
            if ((Ba == 2'b11) && ($time - RCD_chk3 < tRCD))
                $display("at time %t ERROR: tRCD violation during Read or Write to Bank 3", $time);
            // Read Command
            if (Read_enable == 1'b1) begin
                // CAS Latency pipeline
                if (Cas_latency_3 == 1'b1) begin
                    if (Addr[10] == 1'b1) begin
                        Command[2] = `READ_A;
                    end else begin
                        Command[2] = `READ;
                    end
                    Col_addr[2] = Addr;
                    Bank_addr[2] = Ba;
                end else if (Cas_latency_2 == 1'b1) begin
                    if (Addr[10] == 1'b1) begin
                        Command[1] = `READ_A;
                    end else begin
                        Command[1] = `READ;
                    end
                    Col_addr[1] = Addr;
                    Bank_addr[1] = Ba;
                end

                // Read interrupt Write (terminate Write immediately)
                if (Data_in_enable == 1'b1) begin
                    Data_in_enable = 1'b0;
                end

            // Write Command
            end else if (Write_enable == 1'b1) begin
                if (Addr[10] == 1'b1) begin
                    Command[0] = `WRITE_A;
                end else begin
                    Command[0] = `WRITE;
                end
                Col_addr[0] = Addr;
                Bank_addr[0] = Ba;

                // Write interrupt Write (terminate Write immediately)
                if (Data_in_enable == 1'b1) begin
                    Data_in_enable = 1'b0;
                end

                // Write interrupt Read (terminate Read immediately)
                if (Data_out_enable == 1'b1) begin
                    Data_out_enable = 1'b0;
                end
            end

            // Interrupting a Write with Autoprecharge
            if (Auto_precharge[Bank] == 1'b1 && Write_precharge[Bank] == 1'b1) begin
                RW_interrupt_write[Bank] = 1'b1;
                if (Debug) $display ("at time %t NOTE : Read/Write Bank %d interrupt Write Bank %d with Autoprecharge", $time, Ba, Bank);
            end

            // Interrupting a Read with Autoprecharge
            if (Auto_precharge[Bank] == 1'b1 && Read_precharge[Bank] == 1'b1) begin
                RW_interrupt_read[Bank] = 1'b1;
                if (Debug) $display ("at time %t NOTE : Read/Write Bank %d interrupt Read Bank %d with Autoprecharge", $time, Ba, Bank);
            end

            // Read or Write with Auto Precharge
            if (Addr[10] == 1'b1) begin
                Auto_precharge[Ba] = 1'b1;
                Count_precharge[Ba] = 0;
                if (Read_enable == 1'b1) begin
                    Read_precharge[Ba] = 1'b1;
                end else if (Write_enable == 1'b1) begin
                    Write_precharge[Ba] = 1'b1;
                end
            end
        end

        //  Read with Auto Precharge Calculation
        //      The device start internal precharge:
        //          1.  CAS Latency - 1 cycles before last burst
        //      and 2.  Meet minimum tRAS requirement
        //       or 3.  Interrupt by a Read or Write (with or without AutoPrecharge)
        if ((Auto_precharge[0] == 1'b1) && (Read_precharge[0] == 1'b1)) begin
            if ((($time - RAS_chk0 >= tRAS) &&                                                      // Case 2
                ((Burst_length_1 == 1'b1 && Count_precharge[0] >= 1) ||                             // Case 1
                 (Burst_length_2 == 1'b1 && Count_precharge[0] >= 2) ||
                 (Burst_length_4 == 1'b1 && Count_precharge[0] >= 4) ||
                 (Burst_length_8 == 1'b1 && Count_precharge[0] >= 8))) ||
                 (RW_interrupt_read[0] == 1'b1)) begin                                              // Case 3
                    Pc_b0 = 1'b1;
                    Act_b0 = 1'b0;
                    RP_chk0 = $time;
                    Auto_precharge[0] = 1'b0;
                    Read_precharge[0] = 1'b0;
                    RW_interrupt_read[0] = 1'b0;
                    if (Debug) $display ("at time %t NOTE : Start Internal Auto Precharge for Bank 0", $time);
            end
        end
        if ((Auto_precharge[1] == 1'b1) && (Read_precharge[1] == 1'b1)) begin
            if ((($time - RAS_chk1 >= tRAS) &&
                ((Burst_length_1 == 1'b1 && Count_precharge[1] >= 1) || 
                 (Burst_length_2 == 1'b1 && Count_precharge[1] >= 2) ||
                 (Burst_length_4 == 1'b1 && Count_precharge[1] >= 4) ||
                 (Burst_length_8 == 1'b1 && Count_precharge[1] >= 8))) ||
                 (RW_interrupt_read[1] == 1'b1)) begin
                    Pc_b1 = 1'b1;
                    Act_b1 = 1'b0;
                    RP_chk1 = $time;
                    Auto_precharge[1] = 1'b0;
                    Read_precharge[1] = 1'b0;
                    RW_interrupt_read[1] = 1'b0;
                    if (Debug) $display ("at time %t NOTE : Start Internal Auto Precharge for Bank 1", $time);
            end
        end
        if ((Auto_precharge[2] == 1'b1) && (Read_precharge[2] == 1'b1)) begin
            if ((($time - RAS_chk2 >= tRAS) &&
                ((Burst_length_1 == 1'b1 && Count_precharge[2] >= 1) || 
                 (Burst_length_2 == 1'b1 && Count_precharge[2] >= 2) ||
                 (Burst_length_4 == 1'b1 && Count_precharge[2] >= 4) ||
                 (Burst_length_8 == 1'b1 && Count_precharge[2] >= 8))) ||
                 (RW_interrupt_read[2] == 1'b1)) begin
                    Pc_b2 = 1'b1;
                    Act_b2 = 1'b0;
                    RP_chk2 = $time;
                    Auto_precharge[2] = 1'b0;
                    Read_precharge[2] = 1'b0;
                    RW_interrupt_read[2] = 1'b0;
                    if (Debug) $display ("at time %t NOTE : Start Internal Auto Precharge for Bank 2", $time);
            end
        end
        if ((Auto_precharge[3] == 1'b1) && (Read_precharge[3] == 1'b1)) begin
            if ((($time - RAS_chk3 >= tRAS) &&
                ((Burst_length_1 == 1'b1 && Count_precharge[3] >= 1) || 
                 (Burst_length_2 == 1'b1 && Count_precharge[3] >= 2) ||
                 (Burst_length_4 == 1'b1 && Count_precharge[3] >= 4) ||
                 (Burst_length_8 == 1'b1 && Count_precharge[3] >= 8))) ||
                 (RW_interrupt_read[3] == 1'b1)) begin
                    Pc_b3 = 1'b1;
                    Act_b3 = 1'b0;
                    RP_chk3 = $time;
                    Auto_precharge[3] = 1'b0;
                    Read_precharge[3] = 1'b0;
                    RW_interrupt_read[3] = 1'b0;
                    if (Debug) $display ("at time %t NOTE : Start Internal Auto Precharge for Bank 3", $time);
            end
        end

        // Internal Precharge or Bst
        if (Command[0] == `PRECH) begin                         // Precharge terminate a read with same bank or all banks
            if (Bank_precharge[0] == Bank || A10_precharge[0] == 1'b1) begin
                if (Data_out_enable == 1'b1) begin
                    Data_out_enable = 1'b0;
                end
            end
        end else if (Command[0] == `BST) begin                  // BST terminate a read to current bank
            if (Data_out_enable == 1'b1) begin
                Data_out_enable = 1'b0;
            end
        end

        if (Data_out_enable == 1'b0) begin
            Dq_reg <= #tOH {data_bits{1'bz}};
        end

        // Detect Read or Write command
        if (Command[0] == `READ || Command[0] == `READ_A) begin
            Bank = Bank_addr[0];
            Col = Col_addr[0];
            Col_brst = Col_addr[0];
            if (Bank_addr[0] == 2'b00) begin
                Row = B0_row_addr;
            end else if (Bank_addr[0] == 2'b01) begin
                Row = B1_row_addr;
            end else if (Bank_addr[0] == 2'b10) begin
                Row = B2_row_addr;
            end else if (Bank_addr[0] == 2'b11) begin
                Row = B3_row_addr;
            end
            Burst_counter = 0;
            Data_in_enable = 1'b0;
            Data_out_enable = 1'b1;
        end else if (Command[0] == `WRITE || Command[0] == `WRITE_A) begin
            Bank = Bank_addr[0];
            Col = Col_addr[0];
            Col_brst = Col_addr[0];
            if (Bank_addr[0] == 2'b00) begin
                Row = B0_row_addr;
            end else if (Bank_addr[0] == 2'b01) begin
                Row = B1_row_addr;
            end else if (Bank_addr[0] == 2'b10) begin
                Row = B2_row_addr;
            end else if (Bank_addr[0] == 2'b11) begin
                Row = B3_row_addr;
            end
            Burst_counter = 0;
            Data_in_enable = 1'b1;
            Data_out_enable = 1'b0;
        end

        // DQ buffer (Driver/Receiver)
        if (Data_in_enable == 1'b1) begin                                   // Writing Data to Memory
            // Array buffer
            if (Bank == 2'b00) Dq_dqm [data_bits - 1  : 0] = Bank0 [{Row, Col}];
            if (Bank == 2'b01) Dq_dqm [data_bits - 1  : 0] = Bank1 [{Row, Col}];
            if (Bank == 2'b10) Dq_dqm [data_bits - 1  : 0] = Bank2 [{Row, Col}];
            if (Bank == 2'b11) Dq_dqm [data_bits - 1  : 0] = Bank3 [{Row, Col}];
            // Dqm operation
            if (Dqm[0] == 1'b0) Dq_dqm [ 7 : 0] = Dq [ 7 : 0];
            if (Dqm[1] == 1'b0) Dq_dqm [15 : 8] = Dq [15 : 8];
            //if (Dqm[2] == 1'b0) Dq_dqm [23 : 16] = Dq [23 : 16];
           // if (Dqm[3] == 1'b0) Dq_dqm [31 : 24] = Dq [31 : 24];
            // Write to memory
            if (Bank == 2'b00) Bank0 [{Row, Col}] = Dq_dqm [data_bits - 1  : 0];
            if (Bank == 2'b01) Bank1 [{Row, Col}] = Dq_dqm [data_bits - 1  : 0];
            if (Bank == 2'b10) Bank2 [{Row, Col}] = Dq_dqm [data_bits - 1  : 0];
            if (Bank == 2'b11) Bank3 [{Row, Col}] = Dq_dqm [data_bits - 1  : 0];
            if (Bank == 2'b11 && Row==10'h3 && Col[7:4]==4'h4)
            	$display("at time %t WRITE: Bank = %d Row = %d, Col = %d, Data = Hi-Z due to DQM", $time, Bank, Row, Col);
            //$fdisplay(test_file,"bank:%h	row:%h	col:%h	write:%h",Bank,Row,Col,Dq_dqm);
            // Output result
            if (Dqm == 4'b1111) begin
                if (Debug) $display("at time %t WRITE: Bank = %d Row = %d, Col = %d, Data = Hi-Z due to DQM", $time, Bank, Row, Col);
            end else begin
                if (Debug) $display("at time %t WRITE: Bank = %d Row = %d, Col = %d, Data = %d, Dqm = %b", $time, Bank, Row, Col, Dq_dqm, Dqm);
                // Record tWR time and reset counter
                WR_chk [Bank] = $time;
                WR_counter [Bank] = 0;
            end
            // Advance burst counter subroutine
            #tHZ Burst;
        end else if (Data_out_enable == 1'b1) begin                         // Reading Data from Memory
        	//$display("%h	,	%h,	%h",Bank0,Row,Col);
            // Array buffer
            if (Bank == 2'b00) Dq_dqm [data_bits - 1  : 0] = Bank0 [{Row, Col}];
            if (Bank == 2'b01) Dq_dqm [data_bits - 1  : 0] = Bank1 [{Row, Col}];
            if (Bank == 2'b10) Dq_dqm [data_bits - 1  : 0] = Bank2 [{Row, Col}];
            if (Bank == 2'b11) Dq_dqm [data_bits - 1  : 0] = Bank3 [{Row, Col}];
            	
            // Dqm operation
            if (Dqm_reg0[0] == 1'b1) Dq_dqm [ 7 : 0] = 8'bz;
            if (Dqm_reg0[1] == 1'b1) Dq_dqm [15 : 8] = 8'bz;
            if (Dqm_reg0[2] == 1'b1) Dq_dqm [23 : 16] = 8'bz;
            if (Dqm_reg0[3] == 1'b1) Dq_dqm [31 : 24] = 8'bz;
            // Display result
            Dq_reg [data_bits - 1  : 0] = #tAC Dq_dqm [data_bits - 1  : 0];
            if (Dqm_reg0 == 4'b1111) begin
                if (Debug) $display("at time %t READ : Bank = %d Row = %d, Col = %d, Data = Hi-Z due to DQM", $time, Bank, Row, Col);
            end else begin
                if (Debug) $display("at time %t READ : Bank = %d Row = %d, Col = %d, Data = %d, Dqm = %b", $time, Bank, Row, Col, Dq_reg, Dqm_reg0);
            end
            // Advance burst counter subroutine
            Burst;
        end
    end

    //  Write with Auto Precharge Calculation
    //      The device start internal precharge:
    //          1.  tWR Clock after last burst
    //      and 2.  Meet minimum tRAS requirement
    //       or 3.  Interrupt by a Read or Write (with or without AutoPrecharge)
    always @ (WR_counter[0]) begin
        if ((Auto_precharge[0] == 1'b1) && (Write_precharge[0] == 1'b1)) begin
            if ((($time - RAS_chk0 >= tRAS) &&                                                          // Case 2
               (((Burst_length_1 == 1'b1 || Write_burst_mode == 1'b1) && Count_precharge [0] >= 1) ||   // Case 1
                 (Burst_length_2 == 1'b1 && Count_precharge [0] >= 2) ||
                 (Burst_length_4 == 1'b1 && Count_precharge [0] >= 4) ||
                 (Burst_length_8 == 1'b1 && Count_precharge [0] >= 8))) ||
                 (RW_interrupt_write[0] == 1'b1 && WR_counter[0] >= 2)) begin                           // Case 3 (stop count when interrupt)
                    Auto_precharge[0] = 1'b0;
                    Write_precharge[0] = 1'b0;
                    RW_interrupt_write[0] = 1'b0;
                    #tWRa;                          // Wait for tWR
                    Pc_b0 = 1'b1;
                    Act_b0 = 1'b0;
                    RP_chk0 = $time;
                    if (Debug) $display ("at time %t NOTE : Start Internal Auto Precharge for Bank 0", $time);
            end
        end
    end
    always @ (WR_counter[1]) begin
        if ((Auto_precharge[1] == 1'b1) && (Write_precharge[1] == 1'b1)) begin
            if ((($time - RAS_chk1 >= tRAS) &&
               (((Burst_length_1 == 1'b1 || Write_burst_mode == 1'b1) && Count_precharge [1] >= 1) || 
                 (Burst_length_2 == 1'b1 && Count_precharge [1] >= 2) ||
                 (Burst_length_4 == 1'b1 && Count_precharge [1] >= 4) ||
                 (Burst_length_8 == 1'b1 && Count_precharge [1] >= 8))) ||
                 (RW_interrupt_write[1] == 1'b1 && WR_counter[1] >= 2)) begin
                    Auto_precharge[1] = 1'b0;
                    Write_precharge[1] = 1'b0;
                    RW_interrupt_write[1] = 1'b0;
                    #tWRa;                          // Wait for tWR
                    Pc_b1 = 1'b1;
                    Act_b1 = 1'b0;
                    RP_chk1 = $time;
                    if (Debug) $display ("at time %t NOTE : Start Internal Auto Precharge for Bank 1", $time);
            end
        end
    end
    always @ (WR_counter[2]) begin
        if ((Auto_precharge[2] == 1'b1) && (Write_precharge[2] == 1'b1)) begin
            if ((($time - RAS_chk2 >= tRAS) &&
               (((Burst_length_1 == 1'b1 || Write_burst_mode == 1'b1) && Count_precharge [2] >= 1) || 
                 (Burst_length_2 == 1'b1 && Count_precharge [2] >= 2) ||
                 (Burst_length_4 == 1'b1 && Count_precharge [2] >= 4) ||
                 (Burst_length_8 == 1'b1 && Count_precharge [2] >= 8))) ||
                 (RW_interrupt_write[2] == 1'b1 && WR_counter[2] >= 2)) begin
                    Auto_precharge[2] = 1'b0;
                    Write_precharge[2] = 1'b0;
                    RW_interrupt_write[2] = 1'b0;
                    #tWRa;                          // Wait for tWR
                    Pc_b2 = 1'b1;
                    Act_b2 = 1'b0;
                    RP_chk2 = $time;
                    if (Debug) $display ("at time %t NOTE : Start Internal Auto Precharge for Bank 2", $time);
            end
        end
    end
    always @ (WR_counter[3]) begin
        if ((Auto_precharge[3] == 1'b1) && (Write_precharge[3] == 1'b1)) begin
            if ((($time - RAS_chk3 >= tRAS) &&
               (((Burst_length_1 == 1'b1 || Write_burst_mode == 1'b1) && Count_precharge [3] >= 1) || 
                 (Burst_length_2 == 1'b1 && Count_precharge [3] >= 2) ||
                 (Burst_length_4 == 1'b1 && Count_precharge [3] >= 4) ||
                 (Burst_length_8 == 1'b1 && Count_precharge [3] >= 8))) ||
                 (RW_interrupt_write[3] == 1'b1 && WR_counter[3] >= 2)) begin
                    Auto_precharge[3] = 1'b0;
                    Write_precharge[3] = 1'b0;
                    RW_interrupt_write[3] = 1'b0;
                    #tWRa;                          // Wait for tWR
                    Pc_b3 = 1'b1;
                    Act_b3 = 1'b0;
                    RP_chk3 = $time;
                    if (Debug) $display ("at time %t NOTE : Start Internal Auto Precharge for Bank 3", $time);
            end
        end
    end

    task Burst;
        begin
            // Advance Burst Counter
            Burst_counter = Burst_counter + 1;

            // Burst Type
            if (Mode_reg[3] == 1'b0) begin                                  // Sequential Burst
                Col_temp = Col + 1;
            end else if (Mode_reg[3] == 1'b1) begin                         // Interleaved Burst
                Col_temp[2] =  Burst_counter[2] ^  Col_brst[2];
                Col_temp[1] =  Burst_counter[1] ^  Col_brst[1];
                Col_temp[0] =  Burst_counter[0] ^  Col_brst[0];
            end

            // Burst Length
            if (Burst_length_2) begin                                       // Burst Length = 2
                Col [0] = Col_temp [0];
            end else if (Burst_length_4) begin                              // Burst Length = 4
                Col [1 : 0] = Col_temp [1 : 0];
            end else if (Burst_length_8) begin                              // Burst Length = 8
                Col [2 : 0] = Col_temp [2 : 0];
            end else begin                                                  // Burst Length = FULL
                Col = Col_temp;
            end

            // Burst Read Single Write            
            if (Write_burst_mode == 1'b1) begin
                Data_in_enable = 1'b0;
            end

            // Data Counter
            if (Burst_length_1 == 1'b1) begin
                if (Burst_counter >= 1) begin
                    Data_in_enable = 1'b0;
                    Data_out_enable = 1'b0;
                end
            end else if (Burst_length_2 == 1'b1) begin
                if (Burst_counter >= 2) begin
                    Data_in_enable = 1'b0;
                    Data_out_enable = 1'b0;
                end
            end else if (Burst_length_4 == 1'b1) begin
                if (Burst_counter >= 4) begin
                    Data_in_enable = 1'b0;
                    Data_out_enable = 1'b0;
                end
            end else if (Burst_length_8 == 1'b1) begin
                if (Burst_counter >= 8) begin
                    Data_in_enable = 1'b0;
                    Data_out_enable = 1'b0;
                end
            end
        end
    endtask
    
    //**********************将SDRAM内的数据直接输出到外部文件*******************************//

/*    
   integer	sdram_data,ind;


    [email protected](sdram_r)
	begin
		   sdram_data=$fopen("sdram_data.txt");
		   $display("Sdram dampout begin ",sdram_data);
//		   $fdisplay(sdram_data,"Bank0:");
		   for(ind=0;ind<=mem_sizes;ind=ind+1)
		            $fdisplay(sdram_data,"%h	%b",ind,Bank0[ind]);
//		   $fdisplay(sdram_data,"Bank1:");
		   for(ind=0;ind<=mem_sizes;ind=ind+1)
		            $fdisplay(sdram_data,"%h	%b",ind,Bank1[ind]);
//		   $fdisplay(sdram_data,"Bank2:");
		   for(ind=0;ind<=mem_sizes;ind=ind+1)
		            $fdisplay(sdram_data,"%h	%b",ind,Bank2[ind]);
//	           $fdisplay(sdram_data,"Bank3:");
		   for(ind=0;ind<=mem_sizes;ind=ind+1)
		            $fdisplay(sdram_data,"%h	%b",ind,Bank3[ind]);
		  		    	    	    
		  $fclose("sdram_data.txt");        
	  //->compare;
	  end        
*/
    integer	sdram_data,sdram_mem;
    reg	[23:0]	aa,cc;
    reg	[18:0]	bb,ee;
    
    [email protected](sdram_r)
	begin
		   $display("Sdram dampout begin ",$realtime);
		   sdram_data=$fopen("sdram_data.txt");
		   for(aa=0;aa<4*(mem_sizes+1);aa=aa+1)
		   	begin
		   	bb=aa[18:0];
			if(aa<=mem_sizes)
				$fdisplay(sdram_data,"%0d	%0h",aa,Bank0[bb]);
			else if(aa<=2*mem_sizes+1)
		            	$fdisplay(sdram_data,"%0d	%0h",aa,Bank1[bb]);
			else if(aa<=3*mem_sizes+2)
				$fdisplay(sdram_data,"%0d	%0h",aa,Bank2[bb]);
			else
				$fdisplay(sdram_data,"%0d	%0h",aa,Bank3[bb]);
		  	end	    	    	    
		  $fclose("sdram_data.txt"); 
		  
		  sdram_mem=$fopen("sdram_mem.txt");
		  for(cc=0;cc<4*(mem_sizes+1);cc=cc+1)
		  	begin
		   	ee=cc[18:0];
			if(cc<=mem_sizes)
				$fdisplay(sdram_mem,"%0h",Bank0[ee]);
			else if(cc<=2*mem_sizes+1)
		            	$fdisplay(sdram_mem,"%0h",Bank1[ee]);
			else if(cc<=3*mem_sizes+2)
				$fdisplay(sdram_mem,"%0h",Bank2[ee]);
			else
				$fdisplay(sdram_mem,"%0h",Bank3[ee]);
		  	end	    	    	    
		  $fclose("sdram_mem.txt");        
	 
	  end        



//    // Timing Parameters for -75 (PC133) and CAS Latency = 2
//    specify
//        specparam
                    tAH  =  0.8,                                        // Addr, Ba Hold Time
                    tAS  =  1.5,                                        // Addr, Ba Setup Time
                    tCH  =  2.5,                                        // Clock High-Level Width
                    tCL  =  2.5,                                        // Clock Low-Level Width
//                    tCK  = 10.0,                                       // Clock Cycle Time  100mhz
//                    tCK  = 7.5,    					// Clock Cycle Time  133mhz
                    tCK  =  7,                				// Clock Cycle Time  143mhz
                    tDH  =  0.8,                                        // Data-in Hold Time
                    tDS  =  1.5,                                        // Data-in Setup Time
                    tCKH =  0.8,                                        // CKE Hold  Time
                    tCKS =  1.5,                                        // CKE Setup Time
                    tCMH =  0.8,                                        // CS#, RAS#, CAS#, WE#, DQM# Hold  Time
                    tCMS =  1.5;                                        // CS#, RAS#, CAS#, WE#, DQM# Setup Time
//                    tAH  =  1,                                        // Addr, Ba Hold Time
//                    tAS  =  1.5,                                        // Addr, Ba Setup Time
//                    tCH  =  1,                                        // Clock High-Level Width
//                    tCL  =  3,                                        // Clock Low-Level Width
                    tCK  = 10.0,                                       // Clock Cycle Time  100mhz
                    tCK  = 7.5,    					// Clock Cycle Time  133mhz
//                    tCK  =  7,                				// Clock Cycle Time  143mhz
//                    tDH  =  1,                                        // Data-in Hold Time
//                    tDS  =  2,                                        // Data-in Setup Time
//                    tCKH =  1,                                        // CKE Hold  Time
//                    tCKS =  2,                                        // CKE Setup Time
//                    tCMH =  0.8,                                        // CS#, RAS#, CAS#, WE#, DQM# Hold  Time
//                    tCMS =  1.5;                                        // CS#, RAS#, CAS#, WE#, DQM# Setup Time
//        $width    (posedge Clk,           tCH);
//        $width    (negedge Clk,           tCL);
//        $period   (negedge Clk,           tCK);
//        $period   (posedge Clk,           tCK);
//        $setuphold(posedge Clk,    Cke,   tCKS, tCKH);
//        $setuphold(posedge Clk,    Cs_n,  tCMS, tCMH);
//        $setuphold(posedge Clk,    Cas_n, tCMS, tCMH);
//        $setuphold(posedge Clk,    Ras_n, tCMS, tCMH);
//        $setuphold(posedge Clk,    We_n,  tCMS, tCMH);
//        $setuphold(posedge Clk,    Addr,  tAS,  tAH);
//        $setuphold(posedge Clk,    Ba,    tAS,  tAH);
//        $setuphold(posedge Clk,    Dqm,   tCMS, tCMH);
//        $setuphold(posedge Dq_chk, Dq,    tDS,  tDH);
//    endspecify

endmodule

           
module sdram_read_write(
	input					i_clk,//时钟
	input					i_rst_n,//复位低有效
	input					i_rd_trig,//读指示
	input					i_wr_trig,//写指示
	input	[15:0]		current_state,//状态
	
	output reg			rd_req,//读请求
	output reg			wr_req//写请求
	
);
 
 parameter  Active_wr  = 16'b0000000010000000;//写,激活bank,写入行地址
 parameter  Active_rd  = 16'b0000100000000000;//读,激活bank,写入行地址
 
 

reg			rd_trig_r;//读命令打拍
reg			wr_trig_r;//写命令打拍

//i_rd_trig打一拍
[email protected](posedge i_clk or negedge i_rst_n)begin
			if(i_rst_n == 1'b0)
				rd_trig_r	<=	1'b0;
			else
				rd_trig_r	<=	i_rd_trig;
end

//i_wr_trig打一拍
[email protected](posedge i_clk or negedge i_rst_n)begin
			if(i_rst_n == 1'b0)
				wr_trig_r	<=	1'b0;
			else
				wr_trig_r	<=	i_wr_trig;
end

//读请求
[email protected](posedge i_clk or negedge i_rst_n)begin
			if(i_rst_n == 1'b0)
				rd_req	<=	1'b0;
			else if(i_rd_trig && !rd_trig_r)
				rd_req	<=	1'b1;
			else if(current_state == Active_rd)
				rd_req	<=	1'b0;
			else
				rd_req	<=	rd_req;
			
end				

//写请求
[email protected](posedge i_clk or negedge i_rst_n)begin
			if(i_rst_n == 1'b0)
				wr_req	<=	1'b0;
			else if(i_wr_trig && !wr_trig_r)
				wr_req	<=	1'b1;
			else if(current_state == Active_wr)
				wr_req	<=	1'b0;
			else
				wr_req	<=	wr_req;
			
end

endmodule
           
module sdram_rw_test(
	input						i_clk,//输入时钟100M
	input						i_rst_n,//复位低有效

	inout   [15:0]       		io_sdram_data, //数据总线
	output               		o_sdram_clk, //sdram时钟,100MHz	

	output  [14:0]				o_sdram_addr,//输出sdram地址	
	output						o_sdram_cke,//输出sdram时钟片选
	output						o_sdram_cs,//输出sdram片选
	output						o_sdram_ras,//输出sdram行有效
	output						o_sdram_cas,//输出sdram列有效
	output						o_sdram_we, //输出sdram写有效
	output              		o_sdram_ldqm,//数据掩码
	output              		o_sdram_udqm //数据掩码

);


wire				i_rd_trig;
wire				i_wr_trig;
wire				i_rd_done;
wire				i_wr_done;
wire				o_data_indi;
wire				o_wr_indi;


wire	[15:0]		wr_data;
reg 	[15:0] 		rd_data;
reg 	[15:0]  	sdram_wr_data ;//写数据
reg					sdram_out_en;


//数据测试模块
data_test	data_test_inst(
			.i_clk(i_clk),
			.i_rst_n(i_rst_n),
			
			.i_wr_indi(o_wr_indi),
			.i_data_indi(o_data_indi),
			
                                     
			.o_wr_trig(i_wr_trig),
			.o_data(wr_data),            
			.o_wr_done(i_wr_done),
               
			.o_rd_trig(i_rd_trig),
			.o_rd_done(i_rd_done) 
                        

   );

					  

//SDRAM模块
sdram_top	sdram_top_inst(
			.i_clk(i_clk),//输入时钟100M
			.i_rst_n(i_rst_n),//复位低有效
			.i_rd_trig(i_rd_trig),//读触发
			.i_wr_trig(i_wr_trig),//写触发

			.i_rd_done(i_rd_done),//sdram读完成指示信号
			.i_wr_done(i_wr_done),//sdram写完成指示信号

			.o_wr_indi(o_wr_indi),//写数据有效
			.o_data_indi(o_data_indi),//读数据有效
			
			.o_sdram_clk(o_sdram_clk),//sdram时钟,100MHz
			.o_sdram_addr(o_sdram_addr),//输出sdram地址	
			.o_sdram_cke(o_sdram_cke),//输出sdram时钟片选
			.o_sdram_cs(o_sdram_cs),//输出sdram片选
			.o_sdram_ras(o_sdram_ras),//输出sdram行有效
			.o_sdram_cas(o_sdram_cas),//输出sdram列有效
			.o_sdram_we(o_sdram_we), //输出sdram写有效

			.o_sdram_ldqm(o_sdram_ldqm),//数据掩码
			.o_sdram_udqm(o_sdram_udqm)//数据掩码
);


assign    	io_sdram_data = sdram_out_en ? sdram_wr_data:16'bz ;  



//SDRAM输出数据使能
[email protected](posedge i_clk or negedge i_rst_n)begin
		if(i_rst_n == 1'b0)
			sdram_out_en <= 1'd0;			
		else if(o_wr_indi)	
			sdram_out_en <= 1'b1;
		else
			sdram_out_en <= 1'b0;
end

//SDRAM写数据
[email protected](posedge i_clk or negedge i_rst_n)begin
		if(i_rst_n == 1'b0)
			sdram_wr_data <= 16'd0;			
		else if(o_wr_indi)	
			sdram_wr_data <= wr_data;	
end

//SDRAM读数据
[email protected](posedge i_clk or negedge i_rst_n)begin
		if(i_rst_n == 1'b0)
			rd_data <= 16'd0;			
		else if(o_data_indi)	
			rd_data <= io_sdram_data;	
end






endmodule
           
module sdram_top(
	input						i_clk,//输入时钟100M
	input						i_rst_n,//复位低有效
	input 						i_rd_trig,//读触发
	input 						i_wr_trig,//写触发
	
	input						i_rd_done,//sdram读完成指示信号
	input						i_wr_done,//sdram写完成指示信号

	output						o_wr_indi,//写数据有效
	output						o_data_indi,//读数据有效
	output						o_sdram_clk,//sdram时钟,100MHz

	output	 [14:0]				o_sdram_addr,//输出sdram地址	
	output						o_sdram_cke,//输出sdram时钟片选
	output						o_sdram_cs,//输出sdram片选
	output						o_sdram_ras,//输出sdram行有效
	output						o_sdram_cas,//输出sdram列有效
	output						o_sdram_we, //输出sdram写有效
	
	output						o_sdram_ldqm,//数据掩码	
	output						o_sdram_udqm//数据掩码
	
	
	
	
);




wire 				refresh_req;//自刷新请求
wire 				cnt_200us_flag;//200us标志信号
wire 				rd_req;//读请求
wire 				wr_req;//写请求
wire [23:0] 		o_addr_bus;//地址输出
wire [15:0] 		current_state;//状态机状态
wire				flag_init_end;//初始化完成

assign		o_sdram_clk = i_clk;
assign  	o_sdram_cke  = 1'b1 ;
assign  	o_sdram_ldqm = 1'b0 ;
assign  	o_sdram_udqm = 1'b0 ;

//初始化和自刷新模块
sdram_init	sdram_init_inst(
	.i_clk(i_clk),
	.i_rst_n(i_rst_n),
	.current_state(current_state),
	.refresh_req(refresh_req),
	.cnt_200us_flag(cnt_200us_flag),
	.flag_init_end(flag_init_end)
	
);

//读写请求模块
sdram_read_write	sdram_read_write_inst(
	.i_clk(i_clk),
	.i_rst_n(i_rst_n),
	.i_rd_trig(i_rd_trig),
	.i_wr_trig(i_wr_trig),
	.current_state(current_state),
	.rd_req(rd_req),
	.wr_req(wr_req)
	
);

//控制模块
sdram_control	sdram_control_inst(
	.i_clk(i_clk),
	.i_rst_n(i_rst_n),
	.rd_req(rd_req),
	.wr_req(wr_req),
	.refresh_req(refresh_req),
	.cnt_200us_flag(cnt_200us_flag),
   .o_wr_indi(o_wr_indi),
   .o_data_indi(o_data_indi),
	.current_state(current_state),
	.flag_init_end(flag_init_end)
		
);

//命令模块
sdram_cmd	sdram_cmd_inst(
	.i_clk(i_clk),
	.i_rst_n(i_rst_n),
	.i_addr_bus(o_addr_bus),
	.o_sdram_addr(o_sdram_addr),
   .o_sdram_cke(),
   .o_sdram_cs(o_sdram_cs),
   .o_sdram_ras(o_sdram_ras),
   .o_sdram_cas(o_sdram_cas),
   .o_sdram_we(o_sdram_we),
   .current_state(current_state)

);

//地址产生模块
sdram_address	sdram_address_inst(
	.i_clk(i_clk),
	.i_rst_n(i_rst_n),
	.i_rd_done(i_rd_done),
   .i_wr_done(i_wr_done),                                                                 
   .i_wr_trig(i_wr_trig),
   .i_rd_trig(i_rd_trig),                
   .o_addr_bus(o_addr_bus)

);


endmodule
           
`timescale 1ns/1ps

module sdram_top_tb ;

reg              i_clk    ;//系统时钟
reg              i_rst_n       ;//reset, 低电平有效


wire [14:0] o_sdram_addr;
wire [15:0] io_sdram_data;
wire		o_sdram_clk;
wire		o_sdram_cke;
wire		o_sdram_cs;
wire		o_sdram_ras;
wire		o_sdram_cas;
wire		o_sdram_we;
wire		o_sdram_ldqm;
wire 		o_sdram_udqm;



         
     
initial  begin                        
	        i_clk 	 = 1'b0 ;           
	        i_rst_n    = 1'b0 ;
			#200			
			i_rst_n    = 1'b1 ;
	       end  

always #10 i_clk = ~i_clk ; 



		   
                                      
sdram_rw_test  sdram_rw_test_inst(
        .i_clk   		( i_clk),                     
        .i_rst_n     	( i_rst_n),                    
                                                                                            
                 
        .io_sdram_data 	(io_sdram_data), //数据总线         
        .o_sdram_clk   	(o_sdram_clk), //sdram时钟,100MHz 
		
        
		.o_sdram_addr  	(o_sdram_addr), //地址总线
        .o_sdram_cke  	(o_sdram_cke),  //控制信号         
        .o_sdram_cs   	(o_sdram_cs),                     
        .o_sdram_ras  	(o_sdram_ras),                     
        .o_sdram_cas  	(o_sdram_cas),                     
        .o_sdram_we   	(o_sdram_we),                     
        .o_sdram_ldqm 	(o_sdram_ldqm),                     
        .o_sdram_udqm 	(o_sdram_udqm)                                           

    ); 
	
	
		

sdram_model_plus  sdram_model_plus_inst(

	.Dq(io_sdram_data), 
	.Addr(o_sdram_addr), 
	.Ba({o_sdram_addr[14],o_sdram_addr[13]}), 
	.Clk(o_sdram_clk), 
	.Cke(o_sdram_cke), 
	.Cs_n(o_sdram_cs), 
	.Ras_n(o_sdram_ras), 
	.Cas_n(o_sdram_cas), 
	.We_n(o_sdram_we), 
	.Dqm({2'b00,o_sdram_ldqm,o_sdram_udqm}),
	.Debug(1'b1)
	);




	
             
endmodule
           
module data_test(
						input  			  			i_clk ,
						input  			  			i_rst_n    ,
				
						input  			  			i_wr_indi	,
						input  			  			i_data_indi	,
								
                                                                 
						output reg        			o_wr_trig  ,
						output  		[15:0] 	  	o_data     ,            
						output reg        			o_wr_done  , 
                
						output reg        			o_rd_trig  ,
						output reg        			o_rd_done 
                          

                      );


parameter	test_lengt = 16'd5;//数据测试长度	


			  				  
reg	wr_indi_r;
reg data_indi_r;

reg	[15:0] init_cnt;
reg	[15:0] wr_count;
reg [15:0] rd_count;
reg	[4:0] count;

wire flag_p1;
wire flag_p2;

assign	flag_p1 = !i_wr_indi && wr_indi_r;//下降沿检测
assign	flag_p2 = !i_data_indi && data_indi_r;//下降沿检测	


//读有效信号打一拍
[email protected](posedge i_clk or negedge i_rst_n)begin
		if(i_rst_n == 1'b0)			
			wr_indi_r	<=	1'b0;
		else 	
			wr_indi_r	<=	i_wr_indi;		
end

//写有效信号打一拍
[email protected](posedge i_clk or negedge i_rst_n)begin
		if(i_rst_n == 1'b0)			
			data_indi_r	<=	1'b0;
		else 	
			data_indi_r	<=	i_data_indi;						
end

//初始化计数
[email protected](posedge i_clk or negedge i_rst_n)begin
		if(i_rst_n == 1'b0)
			init_cnt	<=	16'd0;	
		else if(init_cnt == 16'd25500)
			init_cnt	<=	init_cnt;
		else
			init_cnt	<=	init_cnt + 1'b1;
end

//读写间隔计数
[email protected](posedge i_clk or negedge i_rst_n)begin
		if(i_rst_n == 1'b0)
			count	<=	5'd0;
		else if(count == 5'd20)
			count	<=	5'd0;
		else
			count	<=	count + 1'b1;
end

//写数据计数
[email protected](posedge i_clk or negedge i_rst_n)begin
		if(i_rst_n == 1'b0)
			wr_count	<=	16'd0;
		else if(flag_p1)
			wr_count	<=	wr_count + 1'b1;
		else
			wr_count	<=	wr_count;
end

//读数据计数
[email protected](posedge i_clk or negedge i_rst_n)begin
		if(i_rst_n == 1'b0)
			rd_count	<=	16'd0;
		else if(flag_p2)
			rd_count	<=	rd_count + 1'b1;
		else
			rd_count	<=	rd_count;
end

//输出写命令
[email protected](posedge i_clk or negedge i_rst_n)begin
		if(i_rst_n == 1'b0)
			o_wr_trig	<=	1'd0;
		else if(o_wr_done)
			o_wr_trig	<=	1'd0;		
		else if(init_cnt == 16'd25500 && count == 5'd20)
			o_wr_trig	<=	1'b1;
		else
			o_wr_trig	<=	1'd0;
		
end

//输出读命令
[email protected](posedge i_clk or negedge i_rst_n)begin
		if(i_rst_n == 1'b0)
			o_rd_trig	<=	1'd0;
		else if(o_rd_done)
			o_rd_trig	<=	1'd0;		
		else if(init_cnt == 16'd25500 && count == 5'd20 && o_wr_done)
			o_rd_trig	<=	1'b1;
		else
			o_rd_trig	<=	1'd0;
		
end

//输出写完成信号
[email protected](posedge i_clk or negedge i_rst_n)begin
		if(i_rst_n == 1'b0)			
			o_wr_done	<=	1'd0;
		else if(wr_count == (test_lengt - 1'b1) && flag_p1)
			o_wr_done	<=	1'b1;
		else
			o_wr_done	<=	o_wr_done;
		
end

//输出读完成信号
[email protected](posedge i_clk or negedge i_rst_n)begin
		if(i_rst_n == 1'b0)			
			o_rd_done	<=	1'd0;
		else if(rd_count == (test_lengt - 1'b1) && flag_p2)
			o_rd_done	<=	1'b1;
		else
			o_rd_done	<=	o_rd_done;
		
end


assign	o_data = (i_wr_indi)? wr_count:16'bz;


endmodule
					  
           
module sdram_address(
	input					i_clk,//时钟
	input					i_rst_n,//复位低有效
	input					i_rd_done,//读完成信号
	input					i_wr_done,//写完成信号
	input					i_wr_trig,//写触发
	input					i_rd_trig,//读触发
	
	output reg [23:0]		o_addr_bus//输出地址

);

reg [2:0] crt_state;
reg [2:0] next_state; 
 
parameter Idle      = 3'b001  ;
parameter Wr        = 3'b010  ;
parameter Rd        = 3'b100  ;


reg    			rd_sdram_done ;
reg    			wr_sdram_done ;
reg  			wr_trig_r ;
reg  			rd_trig_r ;
reg [23:0] 		addr_bus_low  ;//产生sdram地址



[email protected](posedge i_clk or negedge i_rst_n)begin
       if(i_rst_n == 1'b0)
              crt_state <= Idle ;
       else
              crt_state <= next_state;
end              
           
 //sdram读写完成指示信号          
[email protected](posedge i_clk or negedge i_rst_n)begin
		if(i_rst_n == 1'b0)begin
			rd_sdram_done <= 1'b0;
			wr_sdram_done <= 1'b0;
			end
		else begin	
			rd_sdram_done <= i_rd_done;
			wr_sdram_done <= i_wr_done;
			end	
end
                                    
       
//写触发信号打一拍
always @(posedge i_clk or negedge i_rst_n)begin
      if(i_rst_n == 1'b0) 
          wr_trig_r <= 1'b0  ;
      else
          wr_trig_r <= i_wr_trig ;
end			 
			 
//读触发信号打一拍          
always @(posedge i_clk or negedge i_rst_n)begin             
      if(i_rst_n == 1'b0)                                
          rd_trig_r <= 1'b0  ;                    
      else                                        
          rd_trig_r <= i_rd_trig ;                
end
              
//sdram地址计数                                                                                                                
[email protected](posedge i_clk or negedge i_rst_n)begin        
       if(i_rst_n == 1'b0)                                   
            addr_bus_low <= 16'b0 ;                   
       else if(crt_state[0])                   
            addr_bus_low <= 16'b0 ; 
       else if((crt_state[1]&&(!wr_trig_r&& i_wr_trig))||(crt_state[2]&&(!rd_trig_r && i_rd_trig )))     //                            
            addr_bus_low <= addr_bus_low +1'b1;          
       else                                           
            addr_bus_low <= addr_bus_low ;   
end                                                                        
                                                                    
[email protected](posedge i_clk or negedge i_rst_n)begin
		if(i_rst_n == 1'b0)
			o_addr_bus	<=	16'b0;
		else		
			o_addr_bus <= addr_bus_low;
end       
         
///=========================================================================

[email protected]( *)
       case(crt_state)
       	    Idle:  	if(!wr_trig_r&& i_wr_trig )//写触发到来
       	                   next_state = Wr  ;
					else if(!rd_trig_r&&i_rd_trig )//读触发到来
       	                   next_state = Rd  ;    
					else
       	                   next_state = crt_state ;
       	           
			Wr:   	if(!wr_sdram_done&&i_wr_done)//写完指示到来
       	                   next_state = Idle  ;
					else
       	                   next_state = crt_state ; 
       	                  
       	     Rd:   	if(!rd_sdram_done&&i_rd_done)//读完指示到来     
       	                   next_state = Idle  ;                      
					else                                                        
       	                   next_state = crt_state ;        	                                                                
       	                   
          default :next_state = Idle  ;
      endcase
 




endmodule
           
module sdram_cmd(
	input									i_clk,//系统时钟
	input									i_rst_n,//复位低有效
	input						[23:0]	i_addr_bus,//输入地址
	input						[15:0]   current_state,

	output	 	wire	 	[14:0]	o_sdram_addr,//输出sdram地址	
	output		wire					o_sdram_cke,//输出sdram时钟片选
	output		wire					o_sdram_cs,//输出sdram片选
	output		wire					o_sdram_ras,//输出sdram行有效
	output		wire					o_sdram_cas,//输出sdram列有效
	output		wire					o_sdram_we //输出sdram写有效

);




 parameter  Idle       = 16'b0000000000000001;//初始状态
 parameter  Precharge  = 16'b0000000000000010;//预充电
 parameter  Pre_nop    = 16'b0000000000000100;//预充电延时
 parameter  Areflash   = 16'b0000000000001000;//自动刷新
 parameter  Are_nop    = 16'b0000000000010000;//自动刷新延时
 parameter  Set_mode   = 16'b0000000000100000;//模式设置
 parameter  Set_nop    = 16'b0000000001000000;//模式设置延时
 
 parameter  Active_wr  = 16'b0000000010000000;//写,激活bank,写入行地址
 parameter  Act_wr_nop = 16'b0000000100000000;//写,激活延时
 parameter  Write      = 16'b0000001000000000;//写人列地址,发出写命令
 parameter  Wr_nop     = 16'b0000010000000000;//写入延时
 
 parameter  Active_rd  = 16'b0000100000000000;//读,激活bank,写入行地址
 parameter  Act_rd_nop = 16'b0001000000000000;//读,激活延时
 parameter  Read       = 16'b0010000000000000;//写入列地址,发出写命令
 parameter  Wait_nop   = 16'b0100000000000000;//等待
 parameter  Data_indi  = 16'b1000000000000000;//fpga读数据


reg		[14:0] 		sdram_addr ;
reg		[4:0] 		sdram_cmd ;

wire	[12:0]      row_addr;
wire    [8:0]       col_addr;
wire    [1:0]       bank_addr;

assign   col_addr   = i_addr_bus[8:0];      // i_addr_bus[8:0] 列地址
assign   row_addr   = i_addr_bus[21: 9];    //i_addr_bus[21:9] 行地址
assign   bank_addr  = i_addr_bus[23:22];    // i_addr_bus[23:22] bank地址



 [email protected]( *)                         
           case(current_state)
		   
           	Data_indi,Idle,
			Pre_nop,Are_nop,
			Set_nop,Act_wr_nop,
			Wr_nop,Act_rd_nop,
			Wait_nop:  sdram_cmd = 5'b10111  ;       //上电
                                               
           	Precharge:  sdram_cmd = 5'b10010  ;      //对bank预充电
                
                   
	         Areflash:  sdram_cmd = 5'b10001  ;     //自刷新       
                   
                                                            
          	Set_mode:  sdram_cmd = 5'b10000  ;     //模式设置      
                 
                                                                  
           	Active_rd,Active_wr:  sdram_cmd = 5'b10011  ;     //激活bank    
                                               
          
          	Write:  sdram_cmd = 5'b10100  ;     //写操作的列地址    
                  
                 
          	Read:  sdram_cmd = 5'b10101  ;    //读操作的列地址          
                                                                          
            default: sdram_cmd = 5'b10111  ;  
            
          endcase                
				  
		assign	{o_sdram_cke,o_sdram_cs,o_sdram_ras,o_sdram_cas,o_sdram_we} = sdram_cmd;
 
  [email protected]( *)    
        case(current_state)
        	 Precharge:  sdram_addr  =15'b000_0100_0000_0000  ;  //A10=1对bank充电
        	 	                          
        	 	      
        	 Set_mode:  sdram_addr  =15'b000_0000_0011_0000  ; //模式设置
                                 //burst type interleave ,cas延时3, write_mode 为0
       	 	        
        	 Active_rd,Active_wr: sdram_addr  = {bank_addr,row_addr} ;   //激活bank,bank、行地址

        	 	       
			 Write,Read: sdram_addr  = {bank_addr,4'b0,col_addr} ;  //列地址

        	        
        	 default: sdram_addr  = 15'b0 ;
        	 
        endcase    
    
		assign	o_sdram_addr = sdram_addr;
        	 
 


endmodule
           
module sdram_control(
	input								i_clk,//时钟
	input								i_rst_n,//复位低有效
	input								rd_req,//读请求
	input								wr_req,//写请求
	input								refresh_req,//自动刷新请求
	input								cnt_200us_flag,//初始化200us标志信号
	
	output							o_wr_indi,//写数据有效
	output							o_data_indi,//读出数据有效
	output	reg [15:0]			current_state,//状态输出
	output	reg					flag_init_end//初始化完成信号
	
	
);




 parameter  Idle       = 16'b0000000000000001;//初始状态
 parameter  Precharge  = 16'b0000000000000010;//预充电
 parameter  Pre_nop    = 16'b0000000000000100;//预充电延时
 parameter  Areflash   = 16'b0000000000001000;//自动刷新
 parameter  Are_nop    = 16'b0000000000010000;//自动刷新延时
 parameter  Set_mode   = 16'b0000000000100000;//模式设置
 parameter  Set_nop    = 16'b0000000001000000;//模式设置延时
 
 parameter  Active_wr  = 16'b0000000010000000;//写,激活bank,写入行地址
 parameter  Act_wr_nop = 16'b0000000100000000;//写,激活延时
 parameter  Write      = 16'b0000001000000000;//写人列地址,发出写命令
 parameter  Wr_nop     = 16'b0000010000000000;//写入延时
 
 parameter  Active_rd  = 16'b0000100000000000;//读,激活bank,写入行地址
 parameter  Act_rd_nop = 16'b0001000000000000;//读,激活延时
 parameter  Read       = 16'b0010000000000000;//写入列地址,发出写命令
 parameter  Wait_nop   = 16'b0100000000000000;//等待
 parameter  Data_indi  = 16'b1000000000000000;//fpga读数据	

//控制状态
reg [15:0] 	next_state ;  
reg [31:0]  state_shift ;//状态转换控制,控制一个命令的周期
reg [24:0]  initial_cnt;//初始化计数
reg [7:0]  	refresh_state ;//自刷新周期

/*********************************************/
//状态转换为ASCII码便于仿真,无实际功能
reg	[127:0] monitor_state;

[email protected](*)
	case(current_state)
		Idle      :monitor_state = "Idle";
		Precharge :monitor_state = "PRE";
		Pre_nop   :monitor_state = "NOP";
		Areflash  :monitor_state = "AREF";
		Are_nop   :monitor_state = "NOP";
		Set_mode  :monitor_state = "MRSET";
		Set_nop   :monitor_state = "NOP";
								   
		Active_wr :monitor_state = "ACT";
		Act_wr_nop:monitor_state = "NOP";
		Write     :monitor_state = "WR";
		Wr_nop    :monitor_state = "NOP";
								   
        Active_rd :monitor_state = "ACT";
        Act_rd_nop:monitor_state = "NOP";
        Read      :monitor_state = "RD";
        Wait_nop  :monitor_state = "NOP";
        Data_indi :monitor_state = "DATA";
	endcase	
/********************************************/ 
 
[email protected](posedge i_clk or negedge i_rst_n)begin
			if(i_rst_n == 1'b0)
             current_state <= Idle;
			else 
             current_state <= next_state;
end

//初始化周期控制
[email protected](posedge i_clk or negedge i_rst_n)begin
			if(i_rst_n == 1'b0)
             initial_cnt <= 25'h1;
			else if(initial_cnt[23])
				 initial_cnt <= initial_cnt;
			else if(cnt_200us_flag)
             initial_cnt <=	initial_cnt<<1;
			else
				 initial_cnt <= initial_cnt;
end

//初始化完成标志信号
[email protected](posedge i_clk or negedge i_rst_n)begin
			if(i_rst_n == 1'b0)
                 flag_init_end <= 1'b0;
			else if(initial_cnt[23])
				 flag_init_end <= 1'b1;			
			else
				 flag_init_end <= flag_init_end;
end


//状态机周期控制
[email protected](posedge i_clk or negedge i_rst_n)begin   
        if(i_rst_n == 1'b0)                   
           state_shift <= 32'h1;
        else if(current_state[0])
           state_shift <= 32'h1;
        else if(initial_cnt[23] && current_state != Idle && current_state != Areflash && current_state != Are_nop)
           state_shift <= state_shift<<1 ;
end



//自动刷新周期控制
[email protected](posedge i_clk or negedge i_rst_n)begin  
        if(i_rst_n == 1'b0)
           refresh_state <= 8'h1 ;
		else if(current_state[0])
		   refresh_state <= 8'h1 ;
        else if(current_state == Areflash || current_state == Are_nop) 
           refresh_state <= refresh_state<<1;
end



//写数据有效标志信号,提前一个周期
assign	o_wr_indi = (current_state==Act_wr_nop && state_shift[4])? 1'b1:1'b0;

//读数据有效标志信号,提前一个周期
assign	o_data_indi	=(current_state==Wait_nop && state_shift[8])? 1'b1:1'b0;		

                  
				  
[email protected]( *) 
       case(current_state)
            	    Idle  : if(initial_cnt[1]) //上电,跳到预充电状态
            	                next_state = Precharge  ;								
            	            else if(refresh_req)//定时刷新 
            	                next_state = Areflash  ;  
            	            else if(wr_req)//
            	                next_state = Active_wr ;
            	            else if(rd_req)
            	                next_state = Active_rd ;  
            	            else 
            	                next_state = current_state ;    
            	                  
				Precharge:	if(initial_cnt[2])   //预充电
								next_state = Pre_nop  ;
							else if(state_shift[10])
								next_state = Pre_nop  ;				
							else 
								next_state = current_state ;
							   
				Pre_nop:  	if(initial_cnt[4])
								next_state = Areflash    ;          
							else if(state_shift[12])
								next_state = Idle  ;	  							  
							else         
								next_state = current_state ;				   
							                   
				Areflash:	if(initial_cnt[5])	//自刷新
								next_state = Are_nop  ;
							else if(initial_cnt[13])
								next_state = Are_nop  ;
							else if(refresh_state[0])
								next_state  = Are_nop  ;		
							else
								next_state = current_state ;
							   
				Are_nop :	if(initial_cnt[12])
								next_state = Areflash    ;          
							else if(initial_cnt[20])
								next_state = Set_mode  ;
							else if(refresh_state[7])
								next_state = Idle  ;	   
							else         
								next_state = current_state ;
			                                
				Set_mode :	if(initial_cnt[21])	//模式设置
								next_state = Set_nop    ;          
							else         
								next_state = current_state ;
							  
				Set_nop	: 	if(initial_cnt[23])
								next_state = Idle    ;          
							else         
								next_state = current_state ;			  
                              
				Active_wr :	if(state_shift[0]) //写激活
								next_state  = Act_wr_nop     ;
							else
								next_state = current_state ;
							 
				Act_wr_nop:	if(state_shift[4])
								next_state  = Write      ;						 
							else
								next_state = current_state ; 
                
				Write  : 	if(state_shift[5])	//写命令
								next_state  = Wr_nop  ;	 
							else 
								next_state = current_state ;	
							  
				Wr_nop :   	if(state_shift[9])
								next_state  = Precharge  ;	 
							else 
								next_state = current_state ;
							  
                              
				Active_rd : if(state_shift[0])	//读激活
                                next_state  = Act_rd_nop     ;
							else
                                next_state = current_state ;
                                                                 
				Act_rd_nop: if(state_shift[4])
								next_state  = Read       ;
							else
								next_state = current_state ;
                              
				Read    : 	if(state_shift[5])	//读命令
								next_state  = Wait_nop       ;  
							else
								next_state = current_state ;
                               
				Wait_nop : 	if(state_shift[8])
                                next_state  = Data_indi  ;
							else
                                next_state = current_state ;
                                
				Data_indi: 	if(state_shift[9])                    
								next_state  = Precharge  ;   
							else                                 
								next_state = current_state ;                 
    
            default:      next_state  = Idle     ;
   
       endcase 
		 


		 

endmodule