昨天做了nand-flash到sdram的4k數(shù)據(jù)的拷貝，數(shù)據(jù)從steppingstone拷貝到sdram上面執(zhí)行；今天接著，將對(duì)nand-flash上4k以后的數(shù)據(jù)進(jìn)行拷貝，所以重點(diǎn)是nand-flash和sdram的控制。

先說(shuō)說(shuō)tq2440開(kāi)發(fā)板。

當(dāng)開(kāi)發(fā)板boot跳線接上時(shí)，處理器上電后從nand-flash啟動(dòng)從0x0開(kāi)始執(zhí)行，nand-flash開(kāi)始的4k數(shù)據(jù)會(huì)自動(dòng)的復(fù)制到內(nèi)部sram執(zhí)行

下面是s3c2440關(guān)于memory啟動(dòng)時(shí)的特性說(shuō)明：

　　In recent times, NOR flash memory gets high in price while an SDRAMand a NAND flash memory is comparativelyeconomical ,motivating some users to execute theboot codeon a NAND flash and execute the main code on an SDRAM.

　　S3C2440A boot code canbe executed on an external NAND flash memory. In order to supportNAND flash boot loader, the S3C2440A is equipped with aninternal SRAM buffer called ‘Steppingstone’. When booting, thefirst 4 KBytes of the NAND flash memory will be loaded intoSteppingstone and the boot code loaded into Steppingstone will beexecuted.

　　Generally,the boot code will copy NAND flash content to SDRAM.Usinghardware ECC, the NAND flash data validity will be checked.Uponthe completion of the copy, the main program will be executed on theSDRAM.

認(rèn)真讀完這幾段，啟動(dòng)時(shí)存儲(chǔ)器的使用過(guò)程將有個(gè)大概的認(rèn)識(shí)。

在上次的實(shí)驗(yàn)中，我們就是控制SDRAM將數(shù)據(jù)從SRAM（steppingstone）拷貝到天嵌開(kāi)發(fā)板上的sdram（使用bank6，地址0x3000000）上。

上圖是我依照自己的理解繪出的啟動(dòng)時(shí)拷貝過(guò)程，敬請(qǐng)指正。