第2部分 嵌入式硬件系统设计2

1、2020/5/12,1,哈尔滨工业大学,(,威海,),通信工程系,第,2,部分,嵌入式系统硬件设计,2020/5/12,哈尔滨工业大学,(,威海,),通信工程系,2,第三节,嵌入式系统总线,概述,AMBA,总线,PCI,总线,CPCI,总线,串行总线,2020/5/12,哈尔滨工业大学,(,威海,),通信工程系,3,串行总线,?,串行总线是指,按位传送数据,的通路,?,其,连接线少、,接口简单、成,本低、传送距,离远,，被广泛,用于嵌入式系,统与外设的连,接和计算机网,络。,2020/5/12,哈尔滨工业大学,(,威海,),通信工程系,4,General concept for Serial

2、Communications,? A point to point communication does not require a Select control signal,? An,asynchronous communication,does not have a Clock signal,? Data, Select and R/W signals can share the same line, depending on the protocol,? Notice that Slave 1 cannot communicate with Slave 2 or 3 (except v

3、ia the master),Only the master can start communicating. Slaves can only speak when spoken to,2020/5/12,哈尔滨工业大学,(,威海,),通信工程系,5,串行总线,Terminology,?,On an,asynchronous bus, data is sent without a timing,clock. A,synchronous bus,sends data with a timing,clock.,?,Full-duplex,means data can be sent and rec

4、eived,simultaneously.,Half-duplex,is when data can be sent,or received, but not at the same time.,?,Master/slave,describes a bus where one device is the,master and others are slaves. Master/slave buses are,usually synchronous, as the master often supplies the,timing clock for data being sent along i

5、n both,directions.,2020/5/12,哈尔滨工业大学,(,威海,),通信工程系,6,串行总线,?,A,multi-master bus,is a master/slave bus that may have more,than one master. These buses must have an,arbitration scheme,that can settle conflicts when more than one master wants to,control the bus at the same time.,?,Point-to-point or peer

6、interfaces,are where two devices have a,peer relation to each other; there are no masters or slaves. Peer,interfaces are most often asynchronous.,?,The term,multi-drop,describes an interface in which there are,several receivers and one transmitter.,?,Multi-point,describes a bus in which there are mo

7、re than two,peer transceivers. This is different from a multi-drop interface,as it allows,bidirectional communication,over the same set of,wires.,2020/5/12,哈尔滨工业大学,(,威海,),通信工程系,7,I2C,?,I2C(Inter,Integrated Circuit),总线产生,于,80,年代，,最初为音频和视频设备开发,。,?,I2C,总线特点,:,简单、有效,?,总线的长度可高达,25,英尺,，并且能够以,10Kbps,的最大传输速

8、率支持,40,个组件。,?,支持,多主控,(multi master),，,其中任何能,够进行发送和接收的设备都可以成为主控。,?,一个主控能够,控制信号的传输和时钟频率,。,2020/5/12,哈尔滨工业大学,(,威海,),通信工程系,8,I2C,?,总线的构成及信号类型,?,I2C,总线是由数据线,SDA,和时钟,SCL,构成的串行总,线,?,在,CPU,与被控,IC,之间、,IC,与,IC,之间进行双向传送，,最高传送速率,100kbps,。,?,在信息的传输过程中，,I2C,总线上并接的每一模块,电路既是主控器（或被控器），又是发送器（或接,收器），这取决于它所要完成的功能。,?,CP

9、U,发出的控制信号分为地址码和控制量两部分，,地址码用来选址。,2020/5/12,哈尔滨工业大学,(,威海,),通信工程系,9,I2C,?,I2C,总线在传送数据过程中共有三种类型信号，它们分别,是：开始信号、结束信号和应答信号。,?,开始信号,：,SCL,为高电平时，,SDA,由高电平向低电平跳变，开始,传送数据。,?,结束信号,：,SCL,为低电平时，,SDA,由低电平向高电平跳变，结束,传送数据。,?,应答信号,：接收数据的,IC,在接收到,8bit,数据后，向发送数据的,IC,发出特定的低电平脉冲，表示已收到数据。,Start bit,Slave,Address,bits,R/W,b

10、it,Ack,bit,8,Data,bits,Ack,bit,8,Dat,a,bits,Ack,bit,Stop bit,2020/5/12,哈尔滨工业大学,(,威海,),通信工程系,10,SPI-,Serial Peripheral Interface,?,SPI,总线接口一般使用,4,条线：,?,串行时钟线（,SCK,）,?,主机输入,/,从机输出数据线,MISO,?,主机输出,/,从机输入数据线,MOST,?,低电平有效的从机选择线,SS,?,有的,SPI,接口芯片带有中断信,号线,INT,、或有的,SPI,接口芯,片没有主机输出,/,从机输入数,据线,MOSI,2020/5/12,哈尔

11、滨工业大学,(,威海,),通信工程系,11,USB,?,Originally a standard for connecting PCs to,peripherals,?,Intended to replace the large number of legacy ports in,the PC,?,Single master (=Host) system with up to 127 peripherals,?,Is simple plug and play; no need to open the PC,?,Standardized plugs, ports, cables,?,Has o

12、ver 99% penetration on all new PCs,?,Serial ports NOT on 2003 PCs,?,New On-The-Go Supplement eliminates PC!,?,Allows dynamic exchanging of Host/Slave roles,?,PC is no longer the only system Host. Can be a,camera, cell phone, printer, PDA, etc.,2020/5/12,哈尔滨工业大学,(,威海,),通信工程系,12,Host,?,One PC host per

13、 system,?,Provides power to peripherals,Hub,?,Provides ports for connecting more,peripheral devices.,?,Provides power, terminations,?,External supply or Bus Powered,USB Topology (original concept, USB1.1, USB2.0),USB Connector,2020/5/12,哈尔滨工业大学,(,威海,),通信工程系,13,?,Convenient link between PC and wide r

14、ange of peripherals,printer, scanner, digital cameras, speakers, monitor,keyboard, mouse, etc.,?,Push for USB to become THE standard on PCs,standard for IBM compatible, (recently) Apple, now on ,99% of PCs,?,Interfaces (bridges) to other comms channels exist,USB to serial port (serial port vanishing

15、 from laptops),USB to IrDA or to Ethernet,USB to Bluetooth,?,Extreme volumes force down IC and hardware prices,Advantage of USB,2020/5/12,哈尔滨工业大学,(,威海,),通信工程系,14,Versions of USB specification,?,USB 1.1,Established, large,PC,peripheral markets,Well controlled hardware, special 4-pin plugs/sockets,12

16、Mbits/sec,(normal) or,1.5 Mbits/sec,(low speed),?,USB 2.0,Supersedes 1.1 specification,? Backwards compatible,? Encompasses LS, FS, HS,Introduces smaller,“mini,-B,” connector,Challenging IEEE1394/Firewire for video possibilities,480 MHz clock for Hi-,Speed means its real “UHF”,Hi-Speed option needs

17、more complex chip H/W & S/W,Hi-Speed component prices x3 approx. compared to full,speed,2020/5/12,哈尔滨工业大学,(,威海,),通信工程系,15,Versions of USB specification,?,USB “OTG” (On The Go) Supplement,Supplement to the 2.0 specification,Allows peripherals to,“talk” to each other,Dynamic host/peripheral switch,Int

18、roduces,new “mini,-,AB” receptacle and “mini,-,A” plug,Lower power requirements,2020/5/12,哈尔滨工业大学,(,威海,),通信工程系,16,第四节,嵌入式存储系统,概述,电子盘,NandFlash,DOC,DOM,CompactFlash,SmartMedia,MemoryStick,MMC,SD,2020/5/12,哈尔滨工业大学,(,威海,),通信工程系,17,概述,?,嵌入式系统的存储结构,嵌入式,微处理器,Cache,片内,RAM,和,ROM,主存：,Nor Flash,、,SRAM,、,DRAM,

19、等,外存：,NandFlash,、,DOC,、,CF,、,SD,、,MMC,等,2020/5/12,哈尔滨工业大学,(,威海,),通信工程系,18,概述,?,高速缓存,Cache,?,高速缓冲存储器中存放的是当前使用得最多,的程序代码和数据，即主存中部分内容的副,本。,?,在嵌入式系统中,Cache,全部都集成在嵌入式,微处理器内。,?,可分为数据,Cache,、指令,Cache,或混合,Cache,。,?,不同的处理器其,Cache,的大小不一样。,?,一般,32,位的嵌入式微处理器都内置,Cache,。,2020/5/12,哈尔滨工业大学,(,威海,),通信工程系,19,概述,?,Cach

20、e,命中,：,CPU,每次读取主存时，,Cache,控制器都要检查,CPU,送出的地址，判断,CPU,要读取的数据是否在,Cache,中，如果在就称,为命中。,?,Cache,未命中,：读取的数据不在,Cache,中，,则对主存储器进行操作，并将有关内容置入,Cache,。,?,写入方法：,?,通,写,（,Write,Through,）,：,写,Cache,时,，,Cache,与对应内存内容同步更新。,?,回写（,Write,Back,）：,写,Cache,时，只有写入,Cache,内容移出时才更新对应内存内容。,2020/5/12,哈尔滨工业大学,(,威海,),通信工程系,20,CPU,地址

21、,索引,机构,置换控制器,高速缓冲,存储器,主,存,段（页）,地址,高位地址,低位地址,地址总线,数据总线,Cache,结构框图,2020/5/12,哈尔滨工业大学,(,威海,),通信工程系,21,概述,?,主存,?,主存是处理器能直接访问的存储器，用来存,放系统和用户的程序和数据。,?,嵌入式系统的主存可位于,SoC,内和,SoC,外，,片内存储器存储容量小、速度快，片外存储,器容量大。,?,可以做主存的存储器有：,?,ROM,类：,Nor Flash,、,EPROM,、,E2PROM,、,PROM,等,?,RAM,类：,SRAM,、,DRAM,、,SDRAM,等,2020/5/12,哈尔滨

22、工业大学,(,威海,),通信工程系,22,?,静态随机存取存储器（,SRAM,）,内部结构,?,由正反器电路组成,S=1,、,R=0,时,输出,Q =1,S=0,、,R=1,时,输出,Q =0,?,每一位存储单元电路,需要,6,个晶体管,图,4-3 SRAM,结构,概述,2020/5/12,哈尔滨工业大学,(,威海,),通信工程系,23,?,特点,?,数据存取速度较快,?,比较容易和处理器制造在同一个芯片中,?,数据不需实时刷新,?,但成本较高,概述,2020/5/12,哈尔滨工业大学,(,威海,),通信工程系,24,概述,?,静态随机存取存储器（,SRAM,）,?,存储信息：六管基本存储电路

23、,?,典型芯片规格：,2114,（,1KX4,）,6116,（,2KX8,）,6264,（,8KX8,）,62128,（,16KX8,）,62256,（,32KX8,）,A,5,A,0,A,2,A,1,CS-,1,9,2114,18,10,V,CC,A,9,I/O,1,A,6,A,4,A,3,A,7,A,8,I/O,2,I/O,3,WE-,符,号,引脚名,A,0,A,9,地址输入,I/0,1,I/0,4,数据输入,/,输出,CS-,片选,WE-,写允许,V,CC,、,GND,电源、地,2020/5/12,哈尔滨工业大学,(,威海,),通信工程系,25,?,动态随机存取存储器（,DRAM,）,内

24、部结构,?,存储单元由一个电,容和一个晶体管组成,?,解码线使晶体管导通后，,通过,rd/wr,线读取电容,电压，或者对电容充放电,?,电容漏电，,15.625,微秒充电一次,图,4-4 DRAM,结构,概述,2020/5/12,哈尔滨工业大学,(,威海,),通信工程系,26,?,特点,?,容量较大，约是,SRAM,的,4,倍,?,成本低,?,但由于电容的充放电原因，数据需要进行实时刷新操作,概述,2020/5/12,哈尔滨工业大学,(,威海,),通信工程系,27,CPU,刷,新,定,时,器,仲裁,电路,定,时,发生器,刷新地址,计数器,地址,多路开关,DRAM,读,/,写,地址总线,地址,R

25、AS,CAS,WR,DRAM Controller,的逻辑框图,2020/5/12,哈尔滨工业大学,(,威海,),通信工程系,28,概述,?,外存,?,外存是,处理器不能直接访问,的存储器，用来,存放用户的各种信息，容量大。,?,在嵌入式系统中常用的外存有：,?,NandFlash,?,DOC,（,Disk On Chip,）,?,CF,（,Compact Flash,）,?,SD,（,Secure Digital,）,?,MMC,（,Multi MediaCard,）等,2020/5/12,哈尔滨工业大学,(,威海,),通信工程系,29,电子盘,?,电子盘采用,半导体芯片,来存贮数据，具,有

26、,体积小,、,功耗低,和,极强的抗震性,等特,点。,?,在嵌入式系统中普遍采用各种电子盘作,为外存。,?,常用的电子盘有：,NandFlash,、,MMC,、,SD,、,Memeory Stick,、,CF,、,SM,、,DOC,等。,2020/5/12,哈尔滨工业大学,(,威海,),通信工程系,30,电子盘,2020/5/12,哈尔滨工业大学,(,威海,),通信工程系,31,电子盘,?,Flash card market for Mobile phone has 70%,CAGR, and 50% market share in 08.,2020/5/12,哈尔滨工业大学,(,威海,),通信

27、工程系,32,Flash,2020/5/12,哈尔滨工业大学,(,威海,),通信工程系,33,Flash,2020/5/12,哈尔滨工业大学,(,威海,),通信工程系,34,Samsung Nandflash,2020/5/12,哈尔滨工业大学,(,威海,),通信工程系,35,NOR,NAND,写入,/,擦除一个块的操,作时间,1,5s,2,4ms,读性能,1200,1500KB,600,800KB,写性能,80KB,200,400KB,接口,/,总线,SRAM,接口,/,独立的地,址数据总线,8,位地址,/,数据,/,控制总线，,I/O,接口复杂,读取模式,随机读取,串行地存取数据,成本,较

28、高,较低，单元尺寸约为,NOR,的一半，,生产过程简单，同样大小的芯片,可以做更大的容量,容量及应用场合,1,64MB,，主要用于,存储代码,8MB,4GB,，主要用于存,储数据,擦写次数,(,耐用性,),约,10,万次,约,100,万次,位交换,(bit,位反转,),少,较多，关键性数据需要错误探,测,/,错误更正,(EDC/ECC),算法,坏块处理,无，因为坏块故障率少,随机分布，无法修正,2020/5/12,哈尔滨工业大学,(,威海,),通信工程系,36,MMC,?,MultiMediaCard Association,?,210+ members,representing the le

29、ading,?,Manufacturers of host systems, cards,components, connectors, etc.,?,Membership: Executive (voting rights) & General,?,Committees: Technical, Marketing, Compliance,?,Open standard, collects no royalties,?,Compliance & certification program,?,Focus on,mobile phones and digital imaging,markets

30、worldwide,2020/5/12,哈尔滨工业大学,(,威海,),通信工程系,37,MMC: Roadmap of capacity,2020/5/12,哈尔滨工业大学,(,威海,),通信工程系,38,MMC,的特点,?,High clock frequency:,26MHz and,52MHz,?,Flexible bus width: 13 pins to,support,1 to 8 data lines,(host-selectable x1,x4 and x8-bit bus),?,Data transfer rate:,up to 52,MBytes/sec,?,This is

31、 the,highest bus transfer rate,of,all flash memory card standards,available,?,Today,Backward compatible,to legacy,hosts,2020/5/12,哈尔滨工业大学,(,威海,),通信工程系,39,MMC,的特点,?,Fully compatible with MMC,plus?,?,The first small form factor memory,card standards to offer,dual-voltage,operation at both 3V and 1.8V,

32、?,Compatible with next generation,mobile phone system specifications,and meets the toughest space,?,Saving and low power consumption,requirements of mobile phones and,small consumer electronics devices,2020/5/12,哈尔滨工业大学,(,威海,),通信工程系,40,SD,?,SD,（,Secure Digital,）卡由松下电器、东芝和,SanDisk,联,合推出，,1999,年,8,月首次

33、发布。,?,2000,年,2,月,1,日成立了,SD,协会（,SDA,），成员公司超过,90,个，其中包括,Hewlett-Packard,，,IBM,，,Microsoft,，,Motorola,，,NEC,、,Samsung Electronics,，,Toyota Motor,等,巨头。,?,SDA,是开放式的，缴纳,1500,美元就可以成为一般会员，,缴纳,4000,美元可以成为执行会员。,SD,存贮卡的详细规,范并没有公开，只有,SDA,会员或签定了保密协议才能,获得。,?,SD,卡需付版税,32,24mm,15,11mm,2020/5/12,哈尔滨工业大学,(,威海,),通信工程系

34、,41,MemoryStick,?,1997,年,7,月,Sony,宣布开发,Memory Stick,?,Memory Stick,被很多人形象地,称为口香糖存贮卡，其尺寸为,50mm,21.5mm,2.8mm,，,重,4,克,?,Memory Stick,也包括了控制器,在内，,采用,10,针接口,，数据总,线为串行，最高频率可达,20MHz,，电压为,2.7,伏到,3.6,伏，,电流平均为,45mA,2020/5/12,哈尔滨工业大学,(,威海,),通信工程系,42,Compact Flash,?,Compact Flash,的诞生比较早，由最大的,Flash Memory,卡厂商之一美国,SanDisk,于,1994,年首次推出。,?,大小仅为,43mm x 36mm x 3.3mm,，体积只有,PCMCIA,卡,的,1/4,，看起来就像是,PCMCIA,卡的缩小版。,?,CompactFlash,提供了完整