SDRAM之刷新（原理分析、波形设计、代码编写、仿真测试）
文章目录
- 功能思路分析
- 如何实现SDRAM读写功能
- SDRAM自刷新描述
- 自动刷新波形
- 时间参数设计看表
- 命令设计看表
- 时钟分析设计：
- 波形设计
- 代码设计
- 状态机设计
- 计数器设计
- 数据存储设计
- main代码
- 刷新模块代码
- 仲裁模块代码
- 顶层模块代码
- 代码编译
- testbench
- 功能仿真
- 总结
功能思路分析
时序接口设计：
- 根据读数据手册步骤分析，看我的博客。
- 对于多时序冲突问题：是否考虑状态机架构
- 看单时序时间参数分析：考虑设计计数器架构；根据单时序一步步执行的命令考虑状态机架构。
- 看命令：command ，查找命令参数表 + 查找不同命令的介绍：如何设置输出端口来实现命令
- 时钟分析：时钟速率；上升沿、下降沿检测（差分时钟设计）
普通设计：
1.根据时间的不同先设计计数器架构，再进行设计其他信号
2.或者考虑先设计状态机架构，选取状态很重要
如何实现SDRAM读写功能
根据数据手册可以进行读写功能，由数据手册得到，只能先进行初始化才能进行后续的写、读、刷新操作。
对于初始化在上个（SDRAM 之初始化博客介绍过了。）那么对于刷新我们该怎么理解呢？
SDRAM自刷新描述
-
为什么要进行刷新？
SDRAM作为一个RAM并没有断电保存的功能，在操作的SDRAM的时候每隔一段时间必须对SDRAM进行自刷新操作，防止SDRAM中的数据丢失。
-
自刷新在SDRAM内部运行状态机如何体现的？PRE命令？
自刷新体现在内部SDRAM里面。
在读结束、或者写结束中遇到了刷新时间到了；或者读写结束后又到了刷新时间，首先给出PRE命令再给2次AUTO FRESH 。后面的 ACTIVE 可以再读写时候给。- 有人疑问读写后面的PRE命令和刷新时序的PRE命令是一样的么是一样的。
- 那么在2个时序都可以写PRE命令么。可以的。因为只要保证SDRAM进行正确跳转就行了。
- 是否可以在写时序不要PRE命令呢？不行，因为要保证写突发结束正确，如果没有PRE，不知道啥时候突发结束了。
- 假设在SDRAM的IDLE状态遇到了PRE咋办，原地踏步就好了
- 这里需要执行ACTIVE么？不需要。在读写执行就好。
- 2次AUTO FRESH 有必要给2次么？没必要只是系统需要执行一次命令长时间就好了
-
选择自刷新还是自动刷新模式？
都可以，自刷新因为路径短更快。自动刷新：操作简单（这里我们选后者）
-
刷新时间间隔多少？
64ms 是电容在未充电的状态下能保持电量的最长时间，也就是 SDRAM 在未刷新的状态下能保存数据的最长时间是 64ms。而SDRAM的刷新操作是一行一行刷新的，该SDRAM一共4096行，所以，每两次刷新的时间间隔大约是 64ms / 4096 = 15.625us。 在本项目中， 我们设置刷新间隔为 15us。
或者理解：刷新4096行总共需要64ms，每行需要 64ms / 4096 = 15.625us。
-
取15us优点？
剩余的0.625us,可以利用来等待写突发、读突发结束。
-
何时才开始刷新？
在读结束、或者写结束中遇到了刷新时间到了；
或者读写结束后又到了刷新时间
-
刷新对于各个模块的影响？
因为写读刷新模块起到冲突，所以要引入仲裁模块来实现不同模块的运转。
由于SDRAM需要同时调控自刷新、读操作、写操作的协调，所以在仲裁控制模块：需要控制三个模块的执行顺序，这三个模块中自刷新命令的优先级最高，但是在执行读写操作时需要等待本次突发结束才可以调到自刷新模块执行，否则就会丢数据。
自动刷新波形
时间参数设计看表
trp含义：上升沿检测到命令1，和检测到命令2之间的时间大于trp,所以不能一直给命令1，
而是给出命令1后，给出空操作，等价于延长第一次SDRAM响应命令的时间，而如果一直给命令1，等价于多次进行相应命令1了。
设置20ns.
TRC：设置80ns.
命令设计看表
从图中我们可以看到COMMAND信号，该信号是由sdram的四个控制信号构成，即sdram_cs_n, sdram_ras_n, sdram_cas_n, sdram_we_n，具体每个命令的编码如下：
同时我们可以看到根据命令输出对应的 DQm A0-A12 DQ0-15 BA0 BA1
针对命令输出相应的值：
NOP：不用管
PRE ：A10=1就可以表示对所有bank充电 BA0 BA1 A0-A12 DQ0-15 不需要设置
（ A10:1 表明对所有bank充电，不需要BA0，BA1设计
A10:0 表明对挑选bank充电，需要对BA0，BA1设计）
AREF：不用管
时钟分析设计：
采用100M设计，便于参数计数。
同时注意：原图上升沿开始检测命令。而我们写代码也是上升沿写命令。考虑采用差分时钟设计。
波形设计
考虑采用计数器架构设计。简单点
由于波形简单就不画了。
代码设计
状态机设计
不采用状态机架构，因为简单，直接采用计数器架构
计数器设计
1.不同时原则，1个计数器可以对不同时间段计数
数据存储设计
main代码
1.case endcase 一起用而且 不要begin end
2.对于输出端口，不能同时赋值，对于多模块都用到这个端口，可以利用暂存器在不同的模块寄存，再输出到顶层模块。
3.信号：0 1 0信号 0 1信号
4.if else 一定要考虑优先级问题
刷新模块代码
//===============================================================================
//******************Cyclone IV E EP4CE15F23C8 ******************************
// 完成自刷新时序操作
//===============================================================================
module sdram_aref (
//system
input wire [0:0] clk ,//系统工作时钟
input wire [0:0] rst_n ,//异步复位
//init
input wire [0:0] init_done ,初始化结束，长1信号
//aref
input wire [0:0] aref_ack ,//自刷新请求
output reg [0:0] aref_req ,//自刷新结束
output reg [0:0] aref_done ,//自刷新完成
//sdram
output reg [3:0] aref_cmd ,//sdram输出端口{sdram_cs，sdram_ras，sdram_cas，sdram_we}
output wire [11:0] aref_addr //sdram地址
);
//===============================================================================
//**************Define Parameter ***************************
//===============================================================================
localparam DELAY_CNT_MAX = 11'd1500 ;//用于15us,电容刷新时间，准确是15.625us
localparam CMD_CNT_MAX = 5 ;//用于命令执行
localparam NOP = 4'b0111 ;//空命令
localparam PRE = 4'b0010 ;//充电命令
localparam AREF = 4'b0001 ;//刷新命令
//===============================================================================
//*********************** Define Intenral Singal ********************************
//===============================================================================
reg [10:0] delay_cnt ;
wire [0:0] add_delay_cnt ;
wire [0:0] end_delay_cnt ;
reg [2:0] cmd_cnt ;
wire [0:0] add_cmd_cnt ;
wire [0:0] end_cmd_cnt ;
reg [0:0] cmd_cnt_flag ;
//===============================================================================
//******************************** Cnt Design **********************************
//===============================================================================
//delay_cnt
always @(posedge clk or negedge rst_n)begin
if(!rst_n)begin
delay_cnt <= 0;
end
else if(add_delay_cnt)begin
if(end_delay_cnt)
delay_cnt <= 0;
else
delay_cnt <= delay_cnt + 1;
end
end
assign add_delay_cnt =init_done==1 ;
assign end_delay_cnt = add_delay_cnt && delay_cnt==DELAY_CNT_MAX-1;
//cmd_cnt
always @(posedge clk or negedge rst_n)begin
if(!rst_n)begin
cmd_cnt <= 0;
end
else if(add_cmd_cnt)begin
if(end_cmd_cnt)
cmd_cnt <= 0;
else
cmd_cnt <= cmd_cnt + 1;
end
end
assign add_cmd_cnt = cmd_cnt_flag==1;
assign end_cmd_cnt = add_cmd_cnt && cmd_cnt==CMD_CNT_MAX-1;
//cmd_cnt_flag
always @(posedge clk or negedge rst_n)begin
if(!rst_n)begin
cmd_cnt_flag <=1'b0 ; //初始化
end
else if(aref_ack==1)begin
cmd_cnt_flag <= 1'b1;
end
else if(end_cmd_cnt)begin
cmd_cnt_flag <= 1'b0 ;
end
end
//===============================================================================
//*********************** Intenral Singal Design ********************************
//===============================================================================
//===============================================================================
//**************************** Output Singal Design *****************************
//===============================================================================
//aref_cmd
always @(posedge clk or negedge rst_n)begin
if(!rst_n)begin
aref_cmd <= NOP ; //初始化
end
else begin
case(cmd_cnt)
1: aref_cmd <= PRE ;
4: aref_cmd <= AREF ;
default:aref_cmd <= NOP;
endcase
end
end
//aref_done:一次时序执行完成算刷新结束了。而不是15us
always @(posedge clk or negedge rst_n)begin
if(!rst_n)begin
aref_done <= 1'b0 ; //初始化
end
else if(end_cmd_cnt == 1'b1)begin
aref_done <= 1'b1 ;
end
else begin
aref_done <= 1'b0 ;
end
end
//aref_req
always @(posedge clk or negedge rst_n)begin
if(!rst_n)begin
aref_req <= 1'b0 ; //初始化
end
else if(end_delay_cnt == 1'b1)begin
aref_req <= 1'b1 ;
end
else if(aref_ack == 1'b1)begin
aref_req <= 1'b0 ;
end
end
//aref_addr
assign aref_addr=12'b0100_0000_0000;
endmodule
仲裁模块代码
由于SDRAM需要同时调控自刷新、读操作、写操作的协调，所以在顶层需要控制三个模块的执行顺序，这三个模块中自刷新命令的优先级最高，但是在执行读写操作时需要等待本次突发结束才可以调到自刷新模块执行，否则就会丢数据。
以刷新操作为例： 当刷新的时间到了之后，刷新模块向仲裁发起刷新请求，然后仲裁老大根据 SDRAM 当前所处的一个状态来判断是否可以允许 SDRAM 进行刷新，当仲裁老大认为 SDRAM 可以刷新了之后，向刷新模块给出刷新使能信号；当刷新模块对 SDRAM 进行刷新完毕后，再向仲裁老大给出刷新结束标志。模块之间的状态转移图如下：
//===============================================================================
//**************************Cyclone IV E EP4CE15F23C8 ***************************
// 仲裁模块
//===============================================================================
module sdram_ctrl (
//system
input wire [0:0] clk ,//
input wire [0:0] rst_n ,//
//init
input wire [0:0] sdram_en ,//
input wire [0:0] init_done ,//
input wire [11:0] init_addr ,//
input wire [3:0] init_cmd ,//
output reg [0:0] init_en ,//
//aref
input wire [0:0] aref_req ,//
input wire [0:0] aref_done ,//
input wire [11:0] aref_addr ,//
input wire [3:0] aref_cmd ,//
output reg [0:0] aref_ack ,//
//sdram输出端口
output reg [0:0] sdram_cke ,//
output reg [1:0] sdram_bank ,//
output reg [0:0] sdram_cs ,//
output reg [0:0] sdram_ras ,//
output reg [0:0] sdram_cas ,//
output reg [0:0] sdram_we ,//
output reg [1:0] sdram_dqm ,//
output reg [11:0] sdram_addr
);
//===============================================================================
//**************************Define Parameter ******************************
//==============================================================================
parameter IDLE = 6'b000001;//空闲状态
parameter SD_INIT = 6'b000010;//初始化状态
parameter SD_ARBIT = 6'b000100;//仲裁状态
parameter SD_AREF = 6'b001000;//刷新状态
//==========================================================================
//******************************** Define Internal Signals ****************
//==========================================================================
reg [5:0] state_c ;//
reg [5:0] state_n ;//
//===============================================================================
//*********************** State Fsm Design ********************************
//===============================================================================
always@(posedge clk or negedge rst_n)begin
if(!rst_n)begin
state_c <= IDLE;
end
else begin
state_c <= state_n;
end
end
always@(*)begin
case(state_c)
IDLE:begin
if(sdram_en)begin
state_n = SD_INIT;
end
else begin
state_n = state_c;
end
end
SD_INIT:begin
if(init_done)begin
state_n = SD_ARBIT;
end
else begin
state_n = state_c;
end
end
SD_ARBIT:begin
if(aref_req)begin
state_n = SD_AREF;
end
else if(wr_req) begin
state_n = SD_WR;
end
else if(rd_req) begin
state_n = SD_RD;
end
else begin
state_n = state_c;
end
end
SD_AREF:begin
if(aref_done)begin
state_n = SD_ARBIT;
end
else begin
state_n = state_c;
end
end
default:begin
state_n = IDLE;
end
endcase
end
//===============================================================================
//**************************** Output Singal Design *****************************
//===============================================================================
//init_en
always @(posedge clk or negedge rst_n)begin
if(!rst_n)begin
init_en<=1'b0 ;
end
else if(state_c==IDLE && sdram_en==1)begin
init_en <= 1'b1;
end
else begin
init_en <= 1'b0;
end
end
/*---------------------------------------------------------------------------------
优先级：aref_req > wr_req > rd_req
----------------------------------------------------------------------------------*/
//aref_ack
always @(posedge clk or negedge rst_n)begin
if(!rst_n)begin
aref_ack<=1'b0 ; //��ʼ��
end
else if(state_c==SD_ARBIT && aref_req==1)begin
aref_ack <= 1'b1;
end
else begin
aref_ack <= 1'b0;
end
end
//sdram 端口
always@(*)begin
case(state_c)
SD_INIT:begin
sdram_cke = 1 ;
sdram_bank = 2'b00;
sdram_cs = init_cmd[3];
sdram_ras = init_cmd[2];
sdram_cas = init_cmd[1];
sdram_we = init_cmd[0];
sdram_dqm = 2'b00 ;
sdram_addr = init_addr ;
end
SD_AREF:begin
sdram_cke = 1 ;
sdram_bank = 2'b00;
sdram_cs = aref_cmd[3];
sdram_ras = aref_cmd[2];
sdram_cas = aref_cmd[1];
sdram_we = aref_cmd[0];
sdram_dqm = 2'b00 ;
sdram_addr = aref_addr ;
end
default:begin
sdram_cke = 1;
sdram_bank = 0;
sdram_cs = 0;
sdram_ras = 1;
sdram_cas = 1;
sdram_we = 1;
sdram_dqm = 2'b00;
sdram_addr = 0 ;
end
endcase
end
endmodule
顶层模块代码
module sdram_top (
//system_clk ,//
input wire [0:0] clk ,//
input wire [0:0] rst_n ,//
//sdram
output wire [0:0] sdram_clk ,//
output wire [0:0] sdram_cke ,//
output wire [0:0] sdram_cs ,//
output wire [0:0] sdram_ras ,//
output wire [0:0] sdram_cas ,//
output wire [0:0] sdram_we ,//
output wire [1:0] sdram_dqm ,//
output wire [1:0] sdram_bank,//
output wire [11:0] sdram_addr
);
//===============================================================================
//*********************** Define Intenral Singal ********************************
//===============================================================================
//init
wire [0:0] init_done ;
wire [0:0] init_en ;
wire [11:0] init_addr ;
wire [3:0] init_cmd ;
//aref
wire [0:0] aref_req ;
wire [0:0] aref_ack ;
wire [0:0] aref_done ;
wire [11:0] aref_addr ;
wire [3:0] aref_cmd ;
//===============================================================================
//*********************** Intenral Singal Design ********************************
//===============================================================================
//===============================================================================
//*********************** Output Singal Design ********************************
//===============================================================================
assign sdram_clk = ~ clk ;
//===============================================================================
//*********************** 例化模块 ************************************
//===============================================================================
sdram_ctrl sdram_ctrl_inst(
.clk (clk ) ,
.rst_n (rst_n ) ,
.sdram_en ( 1 ) ,
.init_done (init_done ) ,
.init_en (init_en ) ,
.init_addr (init_addr ) ,
.init_cmd (init_cmd ) ,
.aref_req (aref_req ) ,
.aref_ack (aref_ack ) ,
.aref_done (aref_done ) ,
.aref_addr (aref_addr ) ,
.aref_cmd (aref_cmd ) ,
.sdram_cke (sdram_cke ) ,
.sdram_cs (sdram_cs ) ,
.sdram_ras (sdram_ras ) ,
.sdram_cas (sdram_cas ) ,
.sdram_we (sdram_we ) ,
.sdram_bank(sdram_bank) ,
.sdram_addr(sdram_addr) ,
.sdram_dqm (sdram_dqm )
);
//init
sdram_init sdram_init_inst(
.clk (clk ) ,
.rst_n (rst_n ) ,
.init_en (init_en ) ,
.init_done (init_done) ,
.init_addr (init_addr) ,
.init_cmd (init_cmd )
);
//aref
sdram_aref sdram_aref_inst(
.clk (clk ) , //系统工作时钟
.rst_n (rst_n ) ,// 异步复位
.init_done(init_done) ,//初始化结束，长1信号
.aref_ack (aref_ack ) ,//自刷新请求
.aref_req (aref_req ) ,//自刷新结束
.aref_done(aref_done) ,//自刷新完成
.aref_cmd (aref_cmd) ,
.aref_addr(aref_addr)
);
endmodule
代码编译
testbench
- 名称和顶层模块一样
- defparam +顶层模块.inst.模块1.inst.CNT=5 改数字
`timescale 1ns / 1ps
`define CLOCK 10 //100M
//==========================================================================
// **************** 顶层测试模型 **************
//==========================================================================
//模型名称和顶层模块前面名字相同
module sdram_top_tb;
//激励源
reg clk ;
reg rst_n ;
//探针检测信号
wire sdram_clk ;
wire sdram_cke ;
wire sdram_cs ;
wire sdram_ras ;
wire sdram_cas ;
wire sdram_we ;
wire [1:0] sdram_dqm ;
wire [1:0] sdram_bank ;
wire [11:0] sdram_addr ;
wire [15:0] sdram_dq ;
//==========================================================================
// **************** 激励源输入，检测原输出 **************
//==========================================================================
sdram_top sdram_top_inst(
.clk (clk ) ,
.rst_n (rst_n ) ,
.sdram_clk (sdram_clk ),
.sdram_cke (sdram_cke ),
.sdram_bank (sdram_bank ),
.sdram_cs (sdram_cs ),
.sdram_ras (sdram_ras ),
.sdram_cas (sdram_cas ),
.sdram_we (sdram_we ),
.sdram_addr (sdram_addr ),
.sdram_dqm (sdram_dqm ),
.sdram_dq (sdram_dq )
);
//sdram模型
sdram_model_plus sdram_model_plus_inst(
.Dq (sdram_dq ),
.Addr (sdram_addr ),
.Ba (sdram_bank ),
.Clk (sdram_clk ),
.Cke (sdram_cke ),
.Cs_n (sdram_cs ),
.Ras_n (sdram_ras ),
.Cas_n (sdram_cas ),
.We_n (sdram_we ),
.Dqm (sdram_dqm ),
.Debug (1'b1 )
);
//==========================================================================
// **************** 初始化激励设置 **************
//==========================================================================
//第一个initial
initial begin
clk = 1'b0;
rst_n <= 1'b0;
#(2*`CLOCK+1);
rst_n <= 1'b1;
end
always #(`CLOCK/2) clk = ~clk;
//==========================================================================
// **************** 参数同一调整设置 **************
//==========================================================================
//对SDRAM模型调整成我们的类型
defparam sdram_model_plus_inst.addr_bits = 12;
defparam sdram_model_plus_inst.data_bits = 16;
defparam sdram_model_plus_inst.col_bits = 9;
defparam sdram_model_plus_inst.mem_sizes = 2*1024*1024; // 2M
endmodule
`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 = 11;
parameter data_bits = 32;
parameter col_bits = 8;
parameter mem_sizes = 1048576*2-1;//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;
always@(posedge Clk)
cke_temp<=Cke;
assign sdram_control={Cs_n,Ras_n,Cas_n,We_n};
always@(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", $time);
end
end
end
task Burst;
begin
// Advance Burst Counter
Burst_counter = Burst_counter + 1;
// Burst Type
if (Mode_reg[3] == 1'b0) begin // Sequential Burst
Col_temp = Col + 1;
end else if (Mode_reg[3] == 1'b1) begin // Interleaved Burst
Col_temp[2] = Burst_counter[2] ^ Col_brst[2];
Col_temp[1] = Burst_counter[1] ^ Col_brst[1];
Col_temp[0] = Burst_counter[0] ^ Col_brst[0];
end
// Burst Length
if (Burst_length_2) begin // Burst Length = 2
Col [0] = Col_temp [0];
end else if (Burst_length_4) begin // Burst Length = 4
Col [1 : 0] = Col_temp [1 : 0];
end else if (Burst_length_8) begin // Burst Length = 8
Col [2 : 0] = Col_temp [2 : 0];
end else begin // Burst Length = FULL
Col = Col_temp;
end
// Burst Read Single Write
if (Write_burst_mode == 1'b1) begin
Data_in_enable = 1'b0;
end
// Data Counter
if (Burst_length_1 == 1'b1) begin
if (Burst_counter >= 1) begin
Data_in_enable = 1'b0;
Data_out_enable = 1'b0;
end
end else if (Burst_length_2 == 1'b1) begin
if (Burst_counter >= 2) begin
Data_in_enable = 1'b0;
Data_out_enable = 1'b0;
end
end else if (Burst_length_4 == 1'b1) begin
if (Burst_counter >= 4) begin
Data_in_enable = 1'b0;
Data_out_enable = 1'b0;
end
end else if (Burst_length_8 == 1'b1) begin
if (Burst_counter >= 8) begin
Data_in_enable = 1'b0;
Data_out_enable = 1'b0;
end
end
end
endtask
//**********************将SDRAM内的数据直接输出到外部文件*******************************//
/*
integer sdram_data,ind;
always@(sdram_r)
begin
sdram_data=$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;
always@(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
SDRAM的测试要有仿真SDRAM模型文件，（引入上述文件作为真实的SDRAM模型）。
功能仿真
.main clear :清空命令行
不要用simulate 用 simulate without…
如何快速检查时序对不对：看仿真模块的输出端口对不对就好，和数据手册时序对比。
由于信号发生冲突了，因为你在不同模块同时输出端口值，肯定会出现混乱。所以我们再顶层模块同一对输出端口进行设置。
看modelsim打印信息就可以了，成功了。
总结
- 本文是基于（串口SDRAM控制读写设计架构，大家可以参考一下）进一步写的。
- 本文从功能原理，波形设计，代码设计，仿真分析比较全面设计。对于初学者有很大帮助哈。
- 本博客还引用了，我在设计时候觉得有用的技巧，欢迎大家补充哈。
- 创作不易，认为文章有帮助的同学们可以关注、点赞、转发支持。
- 欢迎大家在评论区进行评论，一起分享设计