4)USB 2.0使用轮询模型,而超高速使用异步通知。 5)USB 2.0没有流(Streaming)的能力,而超高速支持对批量端点的流(Streaming)。 我们来看一次IN传输: 主机和设备应遵守传输类型和端点特性的限制。主机通过发送一个确认包(IN)到设备发起一次传输。这个确认包包含了将包路由到预想的端点的寻址信息。主机告诉设备它可以...
interface 所描述的是slave开放给host的一个几口,此接口可以包含若干个terminal,其中in-terminal 和out-terminal 成对出现,其标示数据流的方向,最后terminal与endpoint对接。 下图描述了一个麦克风的定义,数据流通过IT(in terminal)进入interface所定义的audio function,通过OT(out terminal)流出,最后送到endpoint In 节点。
video function(视频功能) 位于设备类层次结构中的接口级别。它由许多接口组成,这些接口将相关pipe(管道)分组在一起,共同实现video function(视频功能)的接口。 video function(视频功能)通过其(Video interface)视频接口寻址。每个视频功能都有一个 VideoControl (VC) 接口,并且可以有多个 VideoStreaming (VS) 接口。...
4)USB 2.0使用轮询模型,而超高速使用异步通知。 5)USB 2.0没有流(Streaming)的能力,而超高速支持对批量端点的流(Streaming)。 我们来看一次IN传输: 主机和设备应遵守传输类型和端点特性的限制。主机通过发送一个确认包(IN)到设备发起一次传输。这个确认包包含了将包路由到预想的端点的寻址信息。主机告诉设备它可以...
[drivers/usb/gadget/function/f_uac2.c]structf_uac2 {structg_audio g_audio;// uac2音频设备数据结构/* ac_intf - audio control interface,接口描述符编号为0 * as_in_intf - audio streaming in interface,接口描述符编号为2 * as_out_intf - audio streaming out interface,接口描述符编号为1 ...
The USB audio streaming function of the X-CUBE-USB-AUDIO package is depicted in Figure 2. a. macOS® is a trademark of Apple Inc. registered in the U.S. and other countries. UM2195 Rev 1 9/43 42 USB audio streaming overview Figure 2. Audio streaming model global d...
Device: Multifunction Device: MultiPortSerial Device: Net Device: NetClient Device: NetService Device: NetTrans Device: NtApm Device: PCMCIA Device: Ports Device: Printer Device: Processor Device: SCSIAdapter Device: SmartCardReader Device: System Device: TapeDrive Device: Unknown Device: USB Device...
Something Ive noticed is that the streaming endpoint (EP2 IN) always experiences the UNDERRUN first and then the control endpoint (EP0). I have included a wireshark capture of when an UNDERRUN occurs. The FX3 streams data correctly for a few buffers and then experiences an ...
Audio/video streaming is a typical application for isochronous transfers because it is more important to keep the video and audio up to date at the expense of dropping packets. What is a token packet? The USB protocol defines four types of packets: Start of Frame Token Data Handshake There ...
A Universal Serial Bus (USB) device can support isochronous endpoints to transfer time-dependent data at a steady rate, such as with audio/video streaming. To transfer data, the client driver issues a request to read or write data to an isochronous endpoint. As a result, the host control...