文献翻译-USB相关介绍

Related Presentations of USBUSB, universal serial bus full name, is a two-way, synchronous, serial interface can be hot-swappable, it can be such as game controllers, serial / parallel ports, and input and output devices and other peripheral devices to a above a single bus.USB Request Block; client by I / O request packets (IRP) contains a pointer to a pointer to send URB USB Request Block (URB); URB has a function designed to identify special requests.About USB drive Kernel mode, the USB bus to support a single static image control transfer endpoint, and also supports multiple interrupt transfer endpoint, block input and output block transfer endpoint.Control transfer endpoint and interrupt transfer endpoint need to call the I / O control code and the DeviceIoControl function to achieve hot-swap functionality; block transfer ends by calling the ReadFile and WriteFile functions to achieve the hot swap function.In the call the function DeviceIoControl, ReadFile, WriteFile, you must first call the CreateFile function to obtain a handle to the device.For that you can only support up to a transport endpoint types (control transfer, interrupt transfer, block input, the block output) device, a separate call to the CreateFile function to open multiple transmission channels will be (Pipe), eachcorresponding to an endpoint of a pipe.Configure USB devices :A Universal Serial Bus (USB) device must be explicitly addressed, it can handle I / O. As a USB device supports multiple profiles, customer-driven equipment must be able to read configuration information, analysis of, and then select the appropriate configuration information. USB device descriptor reports through their configuration information: device descriptor contains information about the device as a whole, the information; configuration descriptor contains information about device configuration information for each separate description; string descriptor that contains Unicode formatted text string.Driver according to the following steps to configure their corresponding equipment: 1. Read device descriptor to determine the type of equipment to support the configuration of the number, see the USB device descriptor documentation see more details; 2. Department request from the device descriptor for each configuration; 3. Select the appropriate configuration, will the enable; if the driver program can configure an interface to support every spare setting, then the driver procedures Ke Yi select an alternate interface to enable. USB provides three high-level descriptor for describing a device, they are:USB device descriptor (USB Device Descriptors)，USB configuration descriptor (USB Configuration Descriptors)，USB string descriptors (USB String Descriptors).USB data is transmitted by toggling the data lines between the J state and the opposite K state. USB encodes data using the NRZI convention; a 0 bit is transmitted by toggling the data lines from J to K or vice-versa, while a 1 bit is transmitted by leaving the data lines as-is. To ensure a minimum density of signal transitions, USB uses bit stuffing; an extra 0 bit is inserted into the data stream after any appearance of six consecutive 1 bits. Seven consecutive 1 bits is always an error.A USB frame begins with an 8-bit synchronization sequence 00000001. That is, after the initial idle state J, the data lines toggle KJKJKJKK. The final 1 bit (repeated K state) marks the end of the sync pattern and the beginning of the USB frame.A USB frames end, called EOP (end-of-packet), is indicated by the transmitter driving 2 bit times of SE0 (D+ and D- both below max) and 1 bit time of J state. After this, the transmitter ceases to drive the D+/D lines and the aforementioned resistors hold it in the J (idle) state. A receiver may take extra time to decode the SE0 state, and will see the first bit time as a repetition of the last data bit. Since USB frames are always a multiple of 8 bits long, this extra dribble bit can be detected and ignored.A USB bus is reset using a prolonged (10 to 20 milliseconds) SE0 signal.USB 2.0 devices use a special protocol during reset, called chirping, to negotiate the High-Speed mode with the host/hub. A device that is HS capable first connects as an FS device (D+ pulled high), but upon receiving a USB RESET (both D+ and D- driven LOW by host for 10 to 20 mS) it pulls the D- line high. If the host/hub is also HS capable, it chirps (returns alternating J and K states on D- and D+ lines) letting the device know that the hub will operate at High Speed.Clock tolerance is 480.00 Mbit/s 500 ppm, 12.000 Mbit/s 2500 ppm, 1.50 Mbit/s 15000 ppm.Though Hi-Speed devices are commonly referred to as USB 2.0 and advertised as up to 480 Mbit/s, not all USB 2.0 devices are Hi-Speed. The USB-IF certifies devices and provides licenses to use special marketing logos for either Basic-Speed (low and full) or Hi-Speed after passing a compliance test and paying a licensing fee. All devices are tested according to the latest spec, so recently-compliant Low-Speed devices are also 2.0 devices.The actual throughput currently (2006) attained with real devices is about two thirds of the maximum theoretical bulk data transfer rate of 53.248 MB/s. Typical hi-speed USB devices operate at lower speeds, often about 3 MB/s overall, sometimes up to 1020 MB/s.USB defines class codes used to identify a devices functionality and to load a device driver based on that functionality. This enables a device driver writer to support devices from different manufacturers that comply with a given class code. Data acquisition is not only the important branch of the information-intensive society but also the foundation of production and administration. The date acquisition system which based on USB interface makes the best benefit acquisition system effectively.USB 相关介绍USB，全称通用串行总线，是一种双向的、同步的、可热拔插的串行接口，它可以将诸如游戏控制器，串行/并行端口，以及输入输出设备等周边设备添加到一条单一总线上面。USB 请求块；客户端通过在 I/O 请求包（IRP）中包含一个指向 URB 的指针来发送 USB 请求块（URB） ；URB 中有一个函数专门用来标识特殊请求。USB 驱动简介内核模式下的 USB 总线静态映象支持一个单独的控制传输端点，同时还支持多个中断传输端点，块输入以及块输出传输端点。控制传输端点和中断传输端点需要调用 I/O 控制代码和 DeviceIoControl 函数来实现热拔插功能；块传输端点通过调用函数 ReadFile 和 WriteFile 来实现热拔插功能。在调用函数 DeviceIoControl、ReadFile、WriteFile 之前，必须先调用 CreateFile 函数来获得一个设备句柄。对于那种每次只能支持至多一种传输端点类型（控制传输、中断传输、块输入、块输出）的设备，一个单独的对函数 CreateFile 的调用将会打开多个传输管道（Pipe） ，每一个管道分别对应一个端点。配置 USB 设备一个通用串行总线（USB）设备必须被显式地处理，它才能够处理 I/O。既然一个 USB 设备支持多个配置，客户驱动就要能够读设备配置信息，解析之，然后选择合适的配置信息。USB 设备通过描述符报告它们的配置信息：设备描述符包含关于设备作为一个整体的信息；配置描述符包含关于每一个单独设备配置信息的描述；字符串描述符包含 Unicode 格式的文本字符串。驱动程序按照如下步骤配置它们对应的设备：1. 读取设备描述符来决定设备支持的配置的种类数，参见 USB 设备描述符文档查看更多细节；2. 从设备处请求每一个配置描述符；3. 选择合适的配置，将之使能；如果驱动程序能够为配置的每一个接口支持备用设置，那么驱动程序也可以选择备用接口来使能。USB 提供了三种面向高端级别的描述符来描述一个设备，它们分别是：USB设备描述符（USB Device Descriptors） ，USB 配置描述符（USB Configuration Descriptors） ，USB 字符串描述符（USB String Descriptors） 。USB 数据传输的切换之间的数据线的 J 国和对面 K 状态。编码数据的 USB 接口使用 NRZI 公约; 1 0 位是由切换的数据线从 J 至 K 或反之亦然，而 1 位是由离开数据线原样。为了确保最低密度的信号转换， USB 接口使用比特填充;额外的 0 位是插入到数据流后，任何出现连续 1 位。连续 7 1 位始终是一个错误。 一个 USB 帧始于 8 位同步序列 00000001 。这就是说，在最初的空闲状态 J以来，数据线切换 KJKJKJKK 。最后 1 位（重复 K 国）标志着对同步模式，并开始的 USB 框架。 一个 USB 帧的目的，要求业（结束包） ，是所显示的发射机驾驶 2 位次SE0 （丁+和 D -都低于最大值）和 1 位时间的 J 状态。在此之后，发射机停止硬盘的 D + /名 D -线和上述电阻举行它的 J （空闲）状态。接收器可采取额外的时间来解码 SE0 状态，将看到的第一个位时间的重复过去的数据位。