怎么分析FPGA设计中的DDR2

今天给大家介绍一下怎么分析FPGA设计中的DDR2。文章的内容小编觉得不错，现在给大家分享一下，觉得有需要的朋友可以了解一下，希望对大家有所帮助，下面跟着小编的思路一起来阅读吧。

1. DDR2 IP系统框图
   

2. IP参数设置

1) 时钟设置

PLL reference clock freqency是参考输入时钟，一般由外部晶振或外部PLL输出提供

Memory clock freqency是DDR时钟，一般CYCLONE IV最快只能支持200M，根据不同的型号和BANK而不同

Controller data rate有Full和Half模式，选择Half模式后，Local interface width会增加一倍

2）选择Memory Presets

根据电路中DDR2的型号选择对应的presets,这里只重点介绍Full rate下地址的设置。

在Full rate下：

local_address is 25 bits wide

local_address[23:11] = row address[13:0]

local_address[10:9] = bank address  [1:0]

local_address [8:0] = column address [9:1]

local data宽度是总线data宽度的两倍，所以IP核忽略了column的最低位

3) 设置local参数

Local-to-Memory Address Mapping: 设置地址映射，需要和上面的地址映射说明一致

Local Maximum Burst Count：设置成32，提高读写效率

3. 例化IP核

ddr2_64bit ddr2_64bit_inst (
				.local_address(local_address),
				.local_write_req(local_write_req),
				.local_read_req(local_read_req),
				.local_burstbegin(local_burstbegin),
				.local_wdata(local_wdata),
				.local_be(16'hffff),
				.local_size(BURST_LEN),
				.global_reset_n(rst_n),
				.pll_ref_clk(ref_clk),
				.soft_reset_n(rst_n),
				.local_ready(local_ready),
				.local_rdata(local_rdata),
				.local_rdata_valid(local_rdata_valid),
				.local_refresh_ack(),
				.local_init_done(local_init_done),
				.reset_phy_clk_n(),			
				.phy_clk(phy_clk),
				.aux_full_rate_clk(),
				.aux_half_rate_clk(),
				.reset_request_n(),
				.mem_odt(mem_odt),
				.mem_cs_n(mem_cs_n),
				.mem_cke(mem_cke),
				.mem_addr(mem_addr),
				.mem_ba(mem_ba),
				.mem_ras_n(mem_ras_n),
				.mem_cas_n(mem_cas_n),
				.mem_we_n(mem_we_n),
				.mem_dm(mem_dm),
				.mem_clk(mem_clk),
				.mem_clk_n(mem_clk_n),
				.mem_dq(mem_dq),
				.mem_dqs(mem_dqs)
	);

4. 设计读写测试模块

//-----------ddr2 read and write operation---------
reg   [25 :0]     local_address;
reg               local_burstbegin;
reg               local_read_req;
reg               local_write_req;
reg   [127 :0]    local_wdata;

reg [2:0] local_state;
reg [7:0] local_cnt;
reg [127:0] local_readdata;

parameter IDLE			 = 0,
			 IDLE0 		 = 1,
			 BURST_WRITE = 2,
			 IDLE1		 = 3,
			 BURST_READ	 = 4,
			 END		 = 5;		 
			 
always @(posedge phy_clk)
	if(~rst_n)
	begin
		local_state <= IDLE0;
		local_cnt	<= 0;
	end
	else
		case(local_state)
		IDLE:
		begin
			if(local_init_done & local_ready)
				local_state <= IDLE0;
			else
				local_state <= IDLE;
			local_burstbegin <= 1'b0;
			local_write_req  <= 1'b0;
			local_cnt		  <= 0;
			local_wdata		  <= 128'h0;	
			local_address	  <= 26'd32;	
		end
		IDLE0:
		begin
			if(local_init_done & local_ready)
				local_state <= BURST_WRITE;
			else
				local_state <= IDLE0;
			local_burstbegin <= 1'b0;
			local_write_req  <= 1'b0;
			local_cnt		  <= local_cnt;
			local_wdata		  <= local_wdata;
			local_address	  <= local_address;
		end
		BURST_WRITE:
		begin
			if(local_cnt<=0)
				local_burstbegin <= 1'b1;
			else
				local_burstbegin <= 1'b0;
				
			local_write_req  <= 1'b1;
			local_wdata      <= local_wdata + 1;
			local_read_req	  <= 1'b0;
			local_address	  <= 26'd32;
			
				
			if(local_cnt>=(BURST_LEN-1))
			begin
				local_state <= IDLE1;
				local_cnt <= 0;
			end
			else
			begin
				local_state <= BURST_WRITE;
				local_cnt <= local_cnt + 1'b1;
			end
		end
		IDLE1:
		begin
			if(local_init_done & local_ready)
				local_state <= BURST_READ;
			else
				local_state <= IDLE1;
			local_burstbegin <= 1'b0;
			local_write_req  <= 1'b0;
			local_cnt		  <= local_cnt;	
			local_address	  <= 26'h0;		
		end
		BURST_READ:
		begin
			local_burstbegin <= 1'b1;
			local_write_req  <= 1'b0;
			local_read_req	  <= 1'b1;
			local_cnt		  <= local_cnt;
			local_state		  <= END;
			local_address	  <= 26'd32;
		end
		END:
		begin
			local_burstbegin <= 0;
			local_write_req  <= 0;
			local_read_req   <= 0;
			local_address	  <= 0;
			
			if(local_cnt>=8'h7f)
			begin
					local_state <= IDLE;
					local_cnt   <= 0;
			end
			else
			begin
					local_state <= END;
					local_cnt <= local_cnt + 1'b1;
			end
			
			if(local_rdata_valid)
				local_readdata <= local_rdata;
			else
				local_readdata <= 0;
				
		end
		default: 
		begin
			local_burstbegin <= 1'b0;
			local_write_req  <= 1'b0;
			local_read_req	  <= 1'b0;
			local_cnt		  <= 0;
			local_state		  <= IDLE0;
			local_address	  <= 26'h0;
		end
		endcase

5.测试结果

以上就是怎么分析FPGA设计中的DDR2的全部内容了，更多与怎么分析FPGA设计中的DDR2相关的内容可以搜索亿速云之前的文章或者浏览下面的文章进行学习哈！相信小编会给大家增添更多知识,希望大家能够支持一下亿速云！