描述

隨著消費(fèi)類(lèi)電子產(chǎn)品包括PDA，MP3、智能手機(jī)等手持設(shè)備的市場(chǎng)需求逐步擴(kuò)大，產(chǎn)品間的競(jìng)爭(zhēng)也愈發(fā)激烈，降低產(chǎn)品的設(shè)計(jì)成本，提升產(chǎn)品的市場(chǎng)競(jìng)爭(zhēng)力成為嵌入式系統(tǒng)開(kāi)發(fā)者所面臨的重大挑戰(zhàn)。NANDFLASH和NORFLASH作為兩種主要的非易失性存儲(chǔ)器，被應(yīng)用于各種嵌入式系統(tǒng)。其中NANDFLASH主要優(yōu)點(diǎn)在于存儲(chǔ)密度高、容量大，有更占優(yōu)勢(shì)的存儲(chǔ)性價(jià)比。但是NANDFLASH由于其獨(dú)特的頁(yè)式讀寫(xiě)方式，并不適合程序的直接執(zhí)行。因此，從NANDFLASH啟動(dòng)需要片上存儲(chǔ)器作為代碼執(zhí)行的中轉(zhuǎn)區(qū)。本文所討論的一種系統(tǒng)啟動(dòng)方式，是在缺少片上存儲(chǔ)器支持的情況下，實(shí)現(xiàn)系統(tǒng)直接從NANDFLASH啟動(dòng)。論文中充分考慮了如何實(shí)現(xiàn)軟、硬件之間的協(xié)同工作，以完成SOC系統(tǒng)的設(shè)計(jì)。

2NANDFLASH控制器的結(jié)構(gòu)

本文所討論的NANDFLASH控制器是針對(duì)一款基于ARM7TDMI的SoC芯片，該控制器在芯片中的位置如圖1所示，作為AMBA總線上的一個(gè)從設(shè)備集成于AHB上。主要模塊包括總線接口模塊、FIFO緩沖模塊、ECC編碼模塊以及邏輯控制模塊。

歐美品牌停產(chǎn)的，常用的“PLC”備品備件

我司產(chǎn)品應(yīng)用于以下領(lǐng)域：

1,《發(fā)電廠DCS監(jiān)控系統(tǒng)》

2,《智能平鋼化爐系統(tǒng)制造》

3,《PLC可編程輸送控制系統(tǒng)》

4,《DCS集散控制系統(tǒng)》
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5,《智能型消防供水控制系統(tǒng)》

6,《化工廠藥液恒流量計(jì)算機(jī)控制系統(tǒng)》

7,《電氣控制系統(tǒng)》造紙,印染生產(chǎn)線,變電站綜合自動(dòng)化控制系列

本特利，英維思，伍德沃德，?？怂共_、西屋、瑞恩、施耐德莫迪康、ABB、AB、西門(mén)子、摩托羅拉、GE發(fā)那科、安川、博世力士樂(lè)，ACSO，力士樂(lè)等各大品牌的DCS系統(tǒng)配件，機(jī)器人系統(tǒng)配件，大型伺服系統(tǒng)備件。

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