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1、一、启动1、x-loader是一级引导程序,系统上电后由CPU内部firmware自动拷贝到内部RAM并执行。主要作用为初始化CPU,拷贝u-boot到内存中,然后把控制权交给u-boot;2、u-boot是二级引导程序,主要用于和用户进行交互,提供映像更新、引导内核等功能;3、kernel使用最新2.6.32内核,根据SOC8200进行定制;4、rootfs采用开源文件系统,体积小,功能强大。温馨提示:J24接上跳线帽后,上电启动的时候,系统将会优先从SD卡启动。更新NANDFLASH:更新NANDFlash需要在u-boot的命令行上对
2、NAND操作,系统从SD卡启动后通过U-boot烧写NANDFLASH。第1章Introduction1.1疑问:1)OMAP35xOneDRAM技术具体是指?POP封装顾名思义,是两个芯片叠在一起对于OMAP3的POP封装,OMAP3表面提供焊盘,mDDR贴在OMAP3的表面,Beagle板子就是这样的,这样的好处是省去了PCB面积和DDR的走线,坏处是生产比较困难2)OMAP35x仅有6个GPIO,而AM3517有186个GPIO?解决:Amaximumof170GPIOpinsaresupported.ThefollowingGPIO
3、pinsarenotavailable:gpio_52,gpio_53,gpio_63gpio_64,gpio_144,gpio_145,gpio_146,gpio_147,gpio_152,gpio_153,gpio_154,gpio_155,gpio_175,andgpio_176.PinmuxingrestrictsthetotalnumberofGPIOpinsavailableatonetime.Seeyourdevice-specificdatamanualformoreinformationonpinmultiplexing.
4、3)IVA2.2subsystem(DSP)can’taccessSoCperipherals。(存在质疑,网上说可以)4)Chipselectpinsmcspi1_cs1andmcspi_cs2arenotavailableontheCUSpackage.5)High-speedUSBhostcontrollerport3isnotavailableontheCUSpackage1.2未用模块的建议:GeneralRecommendationsRelativetoUnavailableFeatures/ModulesAsexplained
5、intheprevioussection,somefeaturesarenotavailableinallOMAP35xdevices.Forunavailablefeatures,usethefollowingrecommendations:•Memorymapping:MemoryareaofunavailablemodulesandfeaturesareRESERVED,readisundefined,andwritecanleadtounpredictablebehavior.•Interruptcontrollers:Ensure
6、thatinterruptsofunavailablemodulesandfeaturesaremaskedinMPU/IVAsubsystems.•DMA:EnsurethatDMArequestsofunavailablemodulesandfeaturesaremaskedinDMAsubsystems.•SystemControlModule(SCM):Unavailablemodulesandfeaturepinsarenotfunctionalandshouldnotbeused.•Power,Reset,andClockMan
7、agementModule(PRCM):Forpowermanagementandpower-savingconsideration,ensurethatpowerdomainsofunavailablefeatures/modulesareswitchedoffandclocksarecutoff.•Interconnect:Toflagpotentialinterconnectoutstandingcommands,thetime-outoftargetagentsattachedtounavailablemodulescanbeena
8、bledwiththelowestsetting.第2章MemoryMapping存储空间图见《OMAP35x技术参考手册.pdf》199页2.1地址空间BootspaceThe