In general, the chassis we can buy now provides front-end USB and front-end audio as well as switch-key functions. And the need for us to connect including switch machine button, hard drive indicator, audio interface and USB cable. It is easy to install the
I. Background:The kernel version of ARM Linux is 3.13.0Two. Preparatory workAdd ALSA drivers to the kernel, that is, when compiling the kernel, add the following options:You can then recompile the kernel toThree. Cross-compiling Alsa-lib and Alsa-utils (Alsa-utils is a series of audio device control tools, and Alsa-lib is a library of alsa-utils dependencies, so the Alsa-lib is compiled first)3.1 Cross-comp
OSS audio interface programming in Linux-general Linux technology-Linux programming and kernel information. For details, refer to the following section.
CODE :/*Name: SndKit. cCopyright: GPLv2Author: rockins (email@example.com)Date: 15-10-06Description: implent
: device descriptor, configuration descriptor, string descriptor, interface descriptor, and Endpoint descriptor.(2) a USB device can be regarded as a device that provides multiple serial ports. According to the USB specification, each serial port is called an endpoint to communicate with this endpoint, we need to open the connection to this endpoint, which is the
can contain a number of endpoints. The configuration and interface is the abstraction of the USB device function , and the actual data transfer is done by the endpoint . Before using a USB device, you must indicate the configuration and interface in which it is used. This step is typically done when the device is enum
purpose services defined in the standard time period) and 16-bit "tag" segments, totaling 256 data sequences. For example, the time period "1" and "2" are used to access the encoded control registers, while the time period "3" and "4" load the left and right two audio channels respectively. The "tag" section indicates which of the other segments contains valid data. Dividing a frame into a time period makes it possible for transmission control signal
"tag" segments, A total of 256 data sequences. For example, the time periods "1" and "2" are used to access the control registers of the encoding, while the time periods "3" and "4" load the Left and Right audio channels respectively. The "tag" segment indicates which of the other segments contains valid data. Dividing frames into time periods makes it possible to transmit control signals and audio data on
needs to be configured will be different. Okay, so much about configuration.
For drivers of USB devices, the following interfaces and endpoints are more important. First, let's talk about the interface. First, an interface corresponds to a USB device driver. That's right. Let's look at the example above. One
use another pointer to temporarily replace altsetting. Next we will use its members desc and endpoint.
Looking back at structusb_host_interface, we can see its two members: struct usb_interface_descriptor desc and struct usb_host_endpoint * endpoint. Among them, desc is needless to say, it is the interface descriptor of this interface, and the endpoint pointer records several endpoints, they are stored in
Original article: http://www.gbunix.com/htmldata/2005_05/1/3/article_1193_1.html
Access Windows partition and USB interface mobile hard drive (USB flash drive) in rh9)To access windows partition and USB interface mobile hard drive (USB
the USB device function , and the actual data transfer is done by the endpoint . Before using a USB device, you must indicate the configuration and interface in which it is used. This step is typically done when the device is enumerated when the device is connected to the host.The relationships between these units are as follows:The device usually has one or mor
transmitted.BintervalIf the endpoint is of the interrupt type, this value is the interval setting of the endpoint, in milliseconds.Logically, functions of a USB device are divided by interfaces. For example, a USB speaker may have two interfaces: one for keyboard control and the other for audio stream transmission. In fact, this type of device requires two diffe
Introduction to USB??USB? is English universal? Serial? Bus (universal serial bus) abbreviation, is an external bus standard, used to regulate the connection and communication between the computer and external devices, is applied in the field of PC interface technology. USB interfa
TYPE-C is a USB interface, a connection interface, both sides can be inserted, the size of about 8.3mmx2.5mm, as well as other interfaces to support the USB standard charging, data transmission, display output and other functions. TYPE-C was developed by
Kernel 188.8.131.52 USB devices are actually complicated, but the Linux Kernel provides a subsystem called USB core to handle most of the complicated work. Therefore, the interface between the driver and USB core is described here.In the USB
"linux Audio" ALSA Audio Programming "essence"
Preface: Here is a look at the meaning of each parameter and some basic concepts.
Sample length: Sample is the most basic unit for recording audio data, with 8-bit and 16-bit common.
Channel number (channel): This parameter is 1 for mono, and 2 for stereo. Frame: Hardwoo
(struct ohci hcd *ohci);3 USB Device Driver3.1 USB device drives the overall structureThe following device classes are available
Audio Device class.
Communication Equipment class.
HID (Human-machine interface) device class.
Displays the device class.
Mass storage device class.
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