USB HUB控制芯片解决方案

好玩的 2008-05-11

除了普遍的PC端应用以外,目前USB也逐渐走向嵌入式市场,比如说手机、PMP、PDA、打印机、视讯转换盒、电视盒、家用型NAS服务器等等,由于这一类应用中,通常硬件本身都内建了某种规模的操作系统,因此也具备了程度不等的独立作业能力,在这些装置上的USB架构,除了一般作为与PC平台作为连结之用以外,也具备了USB主控端功能,也就是我们常说的USB OTG。目前普通的USB控制芯片已经非常的廉价,每家厂商都以冲量为主,单一芯片的利润非常微薄,少数具备较高阶应用的芯片产品,如具备高阶制程或者是OTG应用的架构,方有较高的利润。

面对多如过江之鲫的应用。PC主机上内建的USB连接埠相对显得捉襟见肘,常常面临不够用的状况,因此一般来说,大多会以利用USB HUB的方式来进行扩充,因此USB HUB也就成了市面上最为普遍的USB装置之一。不过以HUB的方式扩充,是采用串行单一连接埠的分享方式,因此不仅频宽会被分享,连USB连接埠上的供电也会面临同样的状况,因此USBHUB大多也会设计独立的供电方式,以因应具备较大电源需求的周边。而采用不同的控制芯片的产品,在校能与稳定度表现上也可能会有所不同,

而在建置一整套单芯片USB OTG控制器时,设计者更必须考虑要支持哪些接口,由于支持的接口必须兼容于现今市面上大多数主控端CPU。例如具备支持直接内存存取(DMA)的原生CPU接口,就能藉此支持大多数ARM、MIPS、以及各种精简指令集(RISC)处理器。某些主控端CPU厂商也会针对这些USB OTG控制器推出参考设计方案。至于包括照相手机在内的可携式行动装置,其储存容量不断的增加,因此USB所需传输的流量亦随之不断成长,依此趋势,USB OTG控制芯片不但要求更快,为了行动便利性,也必需要具备更低的功耗表现。

在基于PC的系统中,USB作业一般需要三种组件,分别是通常作为PCI总线子系统的主机控制器、USB堆栈以及USB类驱动器。主机控制器是整合主板芯片组的一部分,USB堆栈则包含主板芯片及通用主机控制器接口(UCHI)和开放主机控制器接口(OHCI)驱动程序以及USB驱动程序(usbd.sys),在PC上要实做这些技术的话,就必须透过以上的方式。至于在在嵌入式USB系统中,其主要组成部分与PC系统类似,如嵌入式主机控制器芯片、内建OHCI堆栈的实时操作系统(RTOS)以及专用驱动程序这几个部件。

过去开发者开发单芯片微控制器或传感器时,大多采用RS-232连结开发平台进行开发。RS-232在测试与量测应用中,仍然是相当普遍的通讯协议,这是由于许多任务控计算机或嵌入式设备大多都承袭旧有计算机架构之故。这个接口广受许多仪器的支持,并且经常用于DUT(待测装置)的诊断或控制埠。RS-232仪器通讯接口的主要优点是成本较低,而且普遍存在于 PC 和旧型仪器中。不过缓慢的速度、不一致的实作方式、以及有限的通讯和搜寻能力,则是它最大的缺点。

当旧型的仪器和设备逐渐被淘汰之后,USB终将取代RS232而成为一般使用者和研发工程师所能使用的接口。但是相较起RS-232,进行实务操作的工程师想要使用USB接口时,仍需要额外的专业知识与需求,大多数的嵌入式系统工程师对位、定时器、输入/输出(I/O)与模拟到数字转换器(ADC)的技术内容都相当熟悉,不过对DLL、组件规格、Windows驱动程序,及遵守USB.org的注册授权与互通性准则等方面,都面临着程度不等的困扰。

■德州仪器 TUSB3210

•Multiproduct Support With One Code and One Chip(up to 16 Products With One Chip)
•Fully Compliant With USB2.0 Full-Speed
•Supports 12Mbits/s USB Data Rate(Full Speed)
•Supports USB Suspend/Resume and Remote Wake-up Operation
•Integrated 8052 Microcontroller
•Four 8052 GPIO Ports, Ports 0,1, 2, and 3
•Master I2C Controller for External Slave Device Access
•Watchdog Timer
•Operates From a 12MHz Crystal
•On-Chip PLL Generates 48MHz
•Power-Down Mode

■Alcor Micro AU9254

•Fully compliant with the Universal Serial Bus Specification, version 1.1
•USB hub design is compliant with Universal Serial Bus Hub Specification, revision 1.1
•Single chip integrated USB hub controller with embedded proprietary processor
•Supports four bus-powered/self-powered downstream ports
•Built-in 3.3v voltage regulator allows single +5V operating voltage, resulting in reduced overall system cost
•Runs at 12Mhz frequency
•28pin SSOP package, both normal size(body size 209mil)and smaller size(body size 150mil)are available

■Winbond W81E381D

•Full compliance with the USB Specification v2.0
•Support USB Suspend and Resume operation for power-down standby
•Support Microsoft Windows Smart Network Key(WSNK)features
•Support USB remote wake up function
•Embedded 8052 MCU
•Internal generated 12MHz clock for 8052 use
•Flash support 512byte erase block
•Internal PLL fir USB and SC requirement
•USB interrupt uses EX0 and Smart-card interrupt use EX1

■Profilic PL-25A1

•Full compliance with the USB Specification v2.0
•On-chip USB2.0 Phy
•Support both Peer to Peer and Network functions
•Transfer data and share resources between two or more PCs with speed up to 480Mbps
•Remote NDIS specification compliant(For network function only)
•Embedded Turbo 8032 micro-controller
•Supports USB Full/High Speed Control/Interrupt/Bulk Endpoints Transfer
•On-Chip 3.3V∼2.5V regulator for internal circuit
•Dual data buffer supporting two-way data transfer
•Supports Suspend, Resume and Remote wake-up power management features
•Supports external serial EEPROM to customize vender/product related information
•Supports LED indicator for connection and transfer status
•Support external customized program ROM via 100-pin LQFP package
•Bus powered from either USB port
•No glue logic needed – can be embedded in small spaces
•64/100 Pins LQFP packages

■GENESYS GL850G

•Compliant to USB specification Revision 2.0
•On-chip 8-bit RISC micro-processor
•Single Transaction Translator(STT)
•Integrate USB 2.0 transceiver
•Each downstream port supports two-color status indicator, with automatic and manual modes compliant to USB specification Revision 2.0
•Built-in upstream 1.5KΩ pull-up and downstream 15KΩ pull-down
•Embed serial resister for USB signals
•Automatic switching between self-powered and bus-powered modes
•PLL embedded with external 12MHz crystal
•Improve output drivers with slew-rate control for EMI reduction
•Internal power-fail detection for ESD recovery

■NEC μPD720122F1-DN2

•Complaint with USB2.0 specification(Maximum data transferring rate:480Mbps)
•USB2.0 certified(TestID=40000822)
•High(480Mbps)/Full(12Mbps)Speed support and switch automatically
•Easy to design NEC Electronics ASIC
•Generic USB2.0 Device Controller
•Two Bulk End-points and One Interrupt End-point
•Performed Data Local Bus independent from CPU bus(Maximum Data Transferring rate:21MBps with DMA mode)
•Selectable three CPU Bus Interface

■NXP ISP 1521

•Universal Serial Bus Specification Rev. 2.0
•Advanced Configuration and Power Interface(ACPI), OnNow and USB power management requirements
•Self-powered capability
•USB suspend mode support
•Configurable number of ports
•Internal Power-On Reset(POR)and low voltage reset circuit
•Port status indicators
•Built-in overcurrent detection circuit
•Visual USB traffic monitoring(GoodLink)for the upstream facing port
•Uses 12MHz crystal oscillator with on-chip Phase-Locked Loop(PLL)for low ElectroMagnetic Interference(EMI)

希望50年后它依然存在,让我感觉我一直在做一件稍微有点cool的事情 喜欢一起交个朋友吧 微信/QQ :56280295

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