怎么分析FPGA設計中的DDR2

今天給大家介紹一下怎么分析FPGA設計中的DDR2。文章的內容小編覺得不錯，現(xiàn)在給大家分享一下，覺得有需要的朋友可以了解一下，希望對大家有所幫助，下面跟著小編的思路一起來閱讀吧。

1. DDR2 IP系統(tǒng)框圖
   

2. IP參數(shù)設置

1) 時鐘設置

PLL reference clock freqency是參考輸入時鐘，一般由外部晶振或外部PLL輸出提供

Memory clock freqency是DDR時鐘，一般CYCLONE IV最快只能支持200M，根據(jù)不同的型號和BANK而不同

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

2）選擇Memory Presets

根據(jù)電路中DDR2的型號選擇對應的presets,這里只重點介紹Full rate下地址的設置。

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寬度是總線data寬度的兩倍，所以IP核忽略了column的最低位

3) 設置local參數(shù)

Local-to-Memory Address Mapping: 設置地址映射，需要和上面的地址映射說明一致

Local Maximum Burst Count：設置成32，提高讀寫效率

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. 設計讀寫測試模塊

//-----------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.測試結果

以上就是怎么分析FPGA設計中的DDR2的全部內容了，更多與怎么分析FPGA設計中的DDR2相關的內容可以搜索億速云之前的文章或者瀏覽下面的文章進行學習哈！相信小編會給大家增添更多知識,希望大家能夠支持一下億速云！