[信息与通信]嵌入式系统-Chapter2-嵌入式硬件系统基础G.ppt

* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * ARM11 is currently the most power efficient processor on the market, so it makes the best baseline comparison. * * * * * * * * * * * * * * * * SmartMedia  SmartMedia是由东芝公司Toshiba America Electronic Components（TAEC）在1995年11月发布的Flash Memory存贮卡，三星公司在1996年购买了生产和销售许可，这两家公司成为主要的SmartMedia厂商。 SmartMedia 最开始时SmartMedia被称为SSFDC,即Solid State Floppy Disk Card，1996年6月改名为SmartMedia，并成为东芝的注册商标。 SmartMedia采用了NAND型Flash Memory，因此体积做得很小：45mm x 37mm x 0.76mm，非常的薄，仅重1.8克。接口方面，SmartMedia采用了22针的接口，我们在卡上看到的是遍平的金手指。 SmartMedia为了节省成本，存贮卡上只有Flash Memory模块和接口，并没有包括控制芯片，所以使用SmartMedia的设备必须自己装置控制机构。 DOC Disk On Chip，简称DOC，是采用NandFlash芯片作为基本存贮单元，外加一些控制芯片及软件，通过特殊的软硬件来操作的一种模块化、系列化的电子存贮装置。 它采用了TureFFS硬盘仿真技术对Flash进行管理，可以把Flash模拟成为硬盘。 也正是因为采用了TureFFS技术对数据在Flash中的读写操作进行管理，大大提高了DOC的写操作的次数，远远超过了普通Flash的写寿命，提高了Flash的可靠性。 Comparison of Full Size Cards Comparison of Small Size Cards Comparison of Micro Size Cards 谢谢！ * * * * * * * * * * * * * * * * * * * * * * * * * How are the connected devices recognized ? ? USB is essentially a ‘one point to one point’ physical connection The information flow is multiplexed and ‘repeated’ by ‘hubs’ ‘T’ connectors and extension cables are not permitted ? Balanced (differential) bus is unbalanced by resistors in a device to signal a connection has been made, and set Full/Low speed Resistors from bus wires to supply or ground are detected How are the connected devices recognized ? ? Host (= Master = PC usually) asks device to identify itself ? Device sends specific identification – Host / PC needs to have correct software to communicate – Hi-Speed devices send extra signals during the reset period requesting upgrade to high speed mode USB hardware Connections and Terminations 第四节嵌入式存储系统 概述 电子盘—— NandFlash DOC DOM CompactFlash SmartMedia MemoryStick MMC SD 概述 嵌入式系统的存储结构 嵌入式 微处理器