?? 21ic ddr sdram控制器的fpga實(shí)現(xiàn).htm
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<TD align=middle height=31><FONT size=4><B>DDR SDRAM控制器的FPGA實(shí)現(xiàn)
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<TD align=middle height=15>文章作者:施周淵 戴慶元<BR>文章類(lèi)型:設(shè)計(jì)應(yīng)用
文章加入時(shí)間:2004年3月16日0:45</TD></TR>
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style="FONT-FAMILY: 宋體; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">
<B>摘要:</B></SPAN>DDR
SDRAM高容量和快速度的優(yōu)點(diǎn)使它獲得了廣泛的應(yīng)用,但是其接口與目前廣泛應(yīng)用的微處理器不兼容。介紹了一種通用的DDR
SDRAM控制器的設(shè)計(jì),從而使得DDR SDRAM能應(yīng)用到微處理器中去。</P>
<P class=MsoNormal><SPAN
style="FONT-FAMILY: 宋體; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">
<B>關(guān)鍵詞:</B></SPAN>DDR SDRAM控制器 延時(shí)鎖定回路 FPGA</P>
<P style="TEXT-INDENT: 30px">DDR
SDRAM是建立在SDRAM的基礎(chǔ)上的,但是速度和容量卻有了提高。首先,它使用了更多的先進(jìn)的同步電路。其次,它使用延時(shí)鎖定回路提供一個(gè)數(shù)據(jù)濾波信號(hào)。當(dāng)數(shù)據(jù)有效時(shí),存儲(chǔ)器控制器可使用這個(gè)數(shù)據(jù)濾波信號(hào)精確地定位數(shù)據(jù),每16位輸出一次,并且同步來(lái)自不同的雙存儲(chǔ)器模塊的數(shù)據(jù)。</P>
<P style="TEXT-INDENT: 30px">DDR
SDRAM不需要提高時(shí)鐘頻率就能加倍提高SDRAM的速度,因?yàn)樗试S在時(shí)鐘脈沖的上升沿和下降沿讀寫(xiě)數(shù)據(jù)。至于地址和控制信號(hào),還是跟傳統(tǒng)的SDRAM一樣,在時(shí)鐘的上升沿進(jìn)行傳輸。</P>
<P style="TEXT-INDENT: 30px">由于微處理器、DSP等不能直接使用DDR
SDRAM,所以本文介紹一種基于FPGA的DDR SDRAM控制電路。<B><BR><BR><A
href="http://www.21ic.com/info/images/aet/200311/21a.gif">圖1 DDR
SDRAM控制器邏輯圖</A><BR><BR>1 DDR SDRAM控制器的設(shè)計(jì)</B></P>
<P style="TEXT-INDENT: 30px">1.1總體邏輯圖</P>
<P style="TEXT-INDENT: 30px">DDR
SDRAM控制器的總體邏輯圖如圖1所示。主要由DDR控制模塊(Controller)、DDR接口模塊
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