Drivers Apple USB Devices
2021年3月4日Download here: http://gg.gg/ojahy
When you connect your iPhone to computer, instead of automatically launch iTunes, you might find the error message Apple mobile device USB driver was not installed successfully. You might find similar problems for the USB driver of Apple mobile device, Tipard iPhone Transfer Ultimate should be the wonderful solution for you.How to solve Apple mobile device USB driver problem
You can download the latest version of Apple mobile device USB driver, and then make sure you have iTunes and Apple mobile Device support reinstalled.
*1. Go to the Device manager and locate your Apple device.
*2. Right click the device and select ’Update Device Driver’ option.
*3. Find the location for the Drivers and select the file.
*4. Once you install the Apple mobile device USB driver, you can locate the ’Apple Mobile Device USB Driver’ under the ’Universal Serial Device USB Driver’ section in Device Manager.
Right click it and select ’Update Device Driver.’ Navigate to C: Program Files Common Files Apple Mobile Devices Support Drivers and select that folder. The driver should install and you’ll see ’Apple Mobile Device USB Driver’ under the ’Universal Serial Device USB Driver’ section in Device Manager. Apple Mobile Device Usb Driver free download - USB Audio ASIO Driver, Apple iTunes, USB Video Device, and many more programs. Apple Usb Devices Drivers free download - Apple iTunes, Drivers For Free, Apple Safari, and many more programs. The usb mailing list provides a forum for discussing technical issues relating to USB devices in OS X. If you need to develop an in-kernel driver for a USB modem or networking device, refer to the following: IOKit Fundamentals describes the architecture of the I/O Kit, the object-oriented framework for developing OS X device drivers. I read previous inquiries on this site and followed the Microsoft directions to the Device Manager under ’Universal Serial Bus controllers’ but found nothing similar to the above. However, under ’Universal Serial Bus devices’ I found a single file as ’Apple Mobile Device USB Composite Device’.Best method to fix the problems of USB driver of Apple devices
If you do not want to waste more time to hunt for the right Apple mobile device USB driver or fix the tedious problem of Apple mobile device USB driver. If you need to retrieve the files when iTunes not working, or even move iTunes library, you can use Tipard iPhone Transfer Ultimate to sync the data between devices easily.How to fix the problems for Apple mobile device USB driverConnect device to the program
You have to make sure the iPhone or other Apple mobile can be recognized by the computer, and then download and install the program. Connect the device to the program.Select the transfer files from iPhone
You can select the transfer iPhone files without Apple mobile device USB driver download. You can preview the Apple files easily from the program.
You can transfer the iPhone files to the computer or add more the files from your computer to iPhone without installing Apple mobile device USB driver. And you can also add the files to iTunes, which enables you to sync the files easily.
*Transfer all the data of iPhone to computer without downloading USB driver of Apple mobile devices.
*Easily transfer and sync the files without search for the driver of the Apple mobile devices.
*Copy all or selected files from your iPad/iPod to any computer, and sync them to iTunes.Updated by Lily Stark to iPhoneFollow @Lily StarkOctober 30, 2018 07:10
This chapter provides a summary of USB device architecture and describes how USB devices are represented in OS X. It also presents a few specific guidelines for working with USB devices in an application.For details on the USB specification, see http://www.usb.org.USB Device Types and Bus Speeds
The USB specification supports a wide selection of devices that range from lower-speed devices such as keyboards, mice, and joysticks to higher-speed devices such as scanners and digital cameras. The specification lists a number of device classes that each define a set of expected device behaviors. Table 1-1 lists some examples of USB devices, categorized by class.Table 1-1 Examples of USB devices
USB device class
USB devices in class
Audio class
Speakers, microphones
Chip Card Interface Device Class
Smart cards, chip cards
Communication class
Speakerphone, modem
Composite class
A device in which all class-specific information is embedded in its interfaces
HID class
Keyboards, mice, joysticks, drawing tablets
Hub class
Hubs provide additional attachment points for USB devices
Mass storage class
Hard drives, flash memory readers, CD Read/Write drives, digital cameras, and high-end media players
Printing class
Printers
Vendor specific
A device that doesn’t fit into any other predefined class or one that doesn’t use the standard protocols for an existing class
Video class
Digital camcorders, webcams, digital still cameras that support video streaming
Version 1.1 of the USB specification supports two bus speeds:
*
Low speed (1.5 Mbps)
*
Full speed (12 Mbps)
Version 2.0 of the specification adds another bus speed to this list:
*
High speed (480 Mbps)
The USB 2.0 specification is fully compatible with low-speed and full-speed USB devices and even supports the use of cables and connectors made to meet earlier versions of the specification. Apple provides USB 2.0 ports on all new Macintosh computers and fully supports the new specification with Enhanced Host Controller Interface (EHCI) controllers and built-in, low-level USB drivers.
For the most part, you do not have to change existing applications to support the faster data rate because the speed increase and other enhancements are implemented at such a low level. The exceptions to this are some differences in isochronous transfers. For information on how the USB 2.0 specification affects isochronous transfers, see USB 2.0 and Isochronous Transfers.USB Device Architecture and Terminology
The architecture of a generic USB device is multi-layered. A device consists of one or more configurations, each of which describes a possible setting the device can be programmed into. Such settings can include the power characteristics of the configuration (for example, the maximum power consumed by the configuration and whether it is self-powered or not) and whether the configuration supports remote wake-up.
Each configuration contains one or more interfaces that are accessible after the configuration is set. An interface provides the definitions of the functions available within the device and may even contain alternate settings within a single interface. For example, an interface for an audio device may have different settings you can select for different bandwidths.
Each interface contains zero or more endpoints. An endpoint is a uniquely identifiable portion of a USB device that is the source or sink of information in a communication flow between the host and the device. Each endpoint has characteristics that describe the communication it supports, such as transfer type (control, isochronous, interrupt, or bulk, described in USB Transfer Types), maximum packet size, and transfer direction (input or output).
Communication with a USB device is accomplished through a pipe, a logical association between an endpoint and software running on the host. Endpoint and pipe are often used synonymously although an endpoint is a component of a USB device and a pipe is a logical abstraction of the communications link between endpoint and host.USB Device Component Descriptors
Each layer of a USB device provides information about its attributes and resource requirements in its descriptor, a data structure accessible through device interface functions. By examining the descriptors at each layer, you can determine exactly which endpoint you need to communicate successfully with a particular device.
At the top layer is the device descriptor, which has fields associated with information such as the device’s class and subclass, vendor and product numbers, and number of configurations. Each configuration in turn has a configuration descriptor containing fields that describe the number of interfaces it supports and the power characteristics of the device when it is in that configuration, along with other information. Each interface supported by a configuration has its own descriptor with fields for information such as the interface class, subclass, and protocol, and the number of endpoints in that interface. At the bottom layer are the endpoint descriptors that specify attributes such as transfer type and maximum packet size.
The USB specification defines a name for each descriptor field, such as the bDeviceClass field in the device descriptor and the bNumInterfaces field in the configuration descriptor, and each field is associated with a value. For a complete listing of all descriptor fields, see the USB specification at www.usb.org. The USB family defines structures that represent the descriptors defined by the USB specification. For the definitions of these structures, see USB in Kernel Framework Reference.USB Composite Class Devices
The USB specification defines a composite class device as a device whose device-descriptor fields for device class (bDeviceClass) and device subclass (bDeviceSubClass) both have the value 0. A composite class device appears to the system as a USB device using a single bus address that may present multiple interfaces, each of which represents a separate function. A good example of a composite class device is a multifunction device, such as a device that performs printing, scanning, and faxing. In such a device, each function is represented by a separate interface. In OS X, the I/O Kit loads the AppleUSBComposite device driver for composite class devices that do not already have vendor-specific device drivers to drive them. The AppleUSBComposite driver configures the device and causes drivers to be loaded for each USB interface.
Although most multifunction USB devices are composite class devices, not all composite class devices are multifunction devices. The manufacturer of a single-function USB device is at liberty to classify the device as a composite class device as long as the device meets the USB specifications. For more information on how OS X represents USB devices and interfaces, see USB Devices on OS X. USB Transfer Types
The USB specification defines four types of pipe transfer:
*
Control—intended to support configuration, command, and status communication between the host software and the device. Control transfers support error detection and retry.
*
Interrupt—used to support small, limited-latency transfers to or from a device such as coordinates from a pointing device or status changes from a modem. Interrupt transfers support error detection and retry.
*
Isochronous—used for periodic, continuous communication between the host and the device, usually involving time-relevant information such as audio or video data streams. Isochronous transfers do not support error detection or retry.
*
Bulk—intended for non-periodic, large-packet communication with relaxed timing constraints such as between the host software and a printer or scanner. Bulk transfers support error detection and retry.
Pipes also have a transfer direction associated with them. A control pipe can support bidirectional communication but all other pipes are strictly uni-directional. Therefore, two-way communication requires two pipes, one for input and one for output.
Every USB device is required to implement a default control pipe that provides access to the device’s configuration, status, and control information. This pipe, implemented in the IOUSBDevice nub object (described in USB Devices on OS X), is used when a driver such as the AppleUSBComposite driver configures the device or when device-specific control and status information is needed. For example, your application would use the default control pipe if it needs to set or choose a configuration for the device. The default control pipe is connected to the default endpoint (endpoint 0). Note that endpoint 0 does not provide an endpoint descriptor and it is never counted in the total number of endpoints in an interface.
The interfaces associated with a configuration can contain any combination of the three remaining pipe types (interrupt, isochronous, and bulk), implemented in the IOUSBInterface nub objects (described in USB Devices on OS X). Your application can query the interface descriptors of a device to select the pipe most suited to its needs.Stalls and Halts
Although a stall and a halt are different, they are closely related in their effect on data transmission. Halt is a feature of an endpoint and it can be set by either the host or the device itself in response to an error. A stall is a type of handshake packet an endpoint returns when it is unable to transmit or receive data or when its halt feature is set (the host never sends a stall packet). When an endpoint sends a stall packet, the host can halt the endpoint.
Depending on the precise circumstances and on how compliant the device is, the halt feature must be cleared in the host, the endpoint, or both before data transmission can resume. When the halt is cleared the data toggle bit, used to synchronize data transmission, is also reset (see Data Synchronization in Non-Isochronous Transfers for more information about the data toggle). For information on how to handle these conditions in your application, see Handling Stalls, Halts, and Data Toggle Resynchronization.Data Synchronization in Non-Isochronous Transfers
The USB specification defines a simple protocol to provide data synchronization across multiple packets for non-isochronous transfers (recall that isochronous transfers do not support error recovery or retry). The protocol is implemented by means of a data toggle bit in both the host and the endpoint which is synchronized at the start of a transaction (or when a reset occurs). The precise synchronization mechanism varies with the type of transfer; see the USB specification for details.
Both the host and the endpoint begin a transaction with their data toggle bits set to zero. In general, the entity receiving data toggles its data toggle bit when it is able to accept the data and it receives an error-free data packet with the correct identification. The entity sending the data toggles its data toggle bit when it receives a positive acknowledgement from the receiver. In this way, the data toggle bits stay synchronized until, for example, a packet with an incorrect identification is received. When this happens, the receiver ignores the packet and does not increment its data toggle bit. When the data toggle bits get out of synchronization (for this or any other reason), you will probably notice that alternate transactions are not getting through in your application. The solution to this is to resynchronize the data toggle bits. For information on how to do this, see Handling Stalls, Halts, and Data Toggle Resynchronization.USB 2.0 and Isochronous Transfers
The USB 2.0 specification supports the same four transfer types as earlier versions of the specification. In addition to supporting a higher transfer rate, the new specification defines an improved protocol for high-speed transfers and new ways of handling transactions for low-speed and full-speed devices. For details on the protocols and transaction-handling methods, see the specification at http://www.usb.org.
For the most part, these enhancements are implemented at the host software level and do not require changes to your code. For isochronous transfers, however, you should be aware of the following differences:
*
Earlier versions of the specification divide bus time into 1-millisecond frames, each of which can carry multiple transactions to multiple destinations. (A transaction contains two or more packets: a token packet and one or more data packets, a handshake packet, or both.) The USB 2.0 specification divides the 1-millisecond frame into eight, 125-microsecond microframes, each of which can carry multiple transactions to multiple destinations.
*
The maximum amount of data allowed in a transaction is increased to 3 KB.
*
Any isochronous endpoints in a device’s default interface must have a maximum packet size of zero. (This means that the default setting for an interface containing isochronous pipes is alternate setting zero and the maximum packet size for that interface’s isochronous endpoints must be zero.) This ensures that the host can configure the device no matter how busy the bus is.Apple Usb Driver
For a summary of how these differences affect the OS X USB API, see Changes in Isochronous Functions to Support USB 2.0.USB Devices on OS X
When a USB device is plugged in, the OS X USB family abstracts the contents of the device descriptor into an I/O Kit nub object called an IOUSBDevice. This nub object is attached to the IOService plane of the I/O Registry as a child of the driver for the USB controller. The IOUSBDevice nub object is then registered for matching with the I/O Kit.
If the device is a composite class device with no vendor-specific driver to match against it, the AppleUSBComposite driver matches against it and starts as its provider. The AppleUSBComposite driver then configures the device by setting the configuration in the device’s list of configuration descriptors with the maximum power usage that can be satisfied by the port to which the device is attached. This allows a device with a low power and a high power configuration to be configured differently depending on whether it’s attached to a bus-powered hub or a self-powered hub. In addition, if the IOUSBDevice nub object has the “Preferred Configuration” property, the AppleUSBComposite driver will always use that value when it attempts to configure the device.
The configuration of the device causes the USB family to abstract each interface descriptor in the chosen configuration into an IOUSBInterface nub object. These nub objects are attached to the I/O Registry as children of the original IOUSBDevice nub object and are registered for matching with the I/O Kit.
Important: Because a composite class device is configured by the AppleUSBComposite driver, setting the configuration again from your application will result in the destruction of the IOUSBInterface nub objects and the creation of new ones. In general, the only reason to set the configuration of a composite class device that’s matched by the AppleUSBComposite driver is to choose a configuration other than the first one.
For non-composite class devices or composite class devices with vendor-specific drivers that match against them, there is no guarantee that any configuration will be set and you may have to perform this task within your application.
It’s important to be mindful of the difference between a USB device (represented in the I/O Registry by an IOUSBDevi
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When you connect your iPhone to computer, instead of automatically launch iTunes, you might find the error message Apple mobile device USB driver was not installed successfully. You might find similar problems for the USB driver of Apple mobile device, Tipard iPhone Transfer Ultimate should be the wonderful solution for you.How to solve Apple mobile device USB driver problem
You can download the latest version of Apple mobile device USB driver, and then make sure you have iTunes and Apple mobile Device support reinstalled.
*1. Go to the Device manager and locate your Apple device.
*2. Right click the device and select ’Update Device Driver’ option.
*3. Find the location for the Drivers and select the file.
*4. Once you install the Apple mobile device USB driver, you can locate the ’Apple Mobile Device USB Driver’ under the ’Universal Serial Device USB Driver’ section in Device Manager.
Right click it and select ’Update Device Driver.’ Navigate to C: Program Files Common Files Apple Mobile Devices Support Drivers and select that folder. The driver should install and you’ll see ’Apple Mobile Device USB Driver’ under the ’Universal Serial Device USB Driver’ section in Device Manager. Apple Mobile Device Usb Driver free download - USB Audio ASIO Driver, Apple iTunes, USB Video Device, and many more programs. Apple Usb Devices Drivers free download - Apple iTunes, Drivers For Free, Apple Safari, and many more programs. The usb mailing list provides a forum for discussing technical issues relating to USB devices in OS X. If you need to develop an in-kernel driver for a USB modem or networking device, refer to the following: IOKit Fundamentals describes the architecture of the I/O Kit, the object-oriented framework for developing OS X device drivers. I read previous inquiries on this site and followed the Microsoft directions to the Device Manager under ’Universal Serial Bus controllers’ but found nothing similar to the above. However, under ’Universal Serial Bus devices’ I found a single file as ’Apple Mobile Device USB Composite Device’.Best method to fix the problems of USB driver of Apple devices
If you do not want to waste more time to hunt for the right Apple mobile device USB driver or fix the tedious problem of Apple mobile device USB driver. If you need to retrieve the files when iTunes not working, or even move iTunes library, you can use Tipard iPhone Transfer Ultimate to sync the data between devices easily.How to fix the problems for Apple mobile device USB driverConnect device to the program
You have to make sure the iPhone or other Apple mobile can be recognized by the computer, and then download and install the program. Connect the device to the program.Select the transfer files from iPhone
You can select the transfer iPhone files without Apple mobile device USB driver download. You can preview the Apple files easily from the program.
You can transfer the iPhone files to the computer or add more the files from your computer to iPhone without installing Apple mobile device USB driver. And you can also add the files to iTunes, which enables you to sync the files easily.
*Transfer all the data of iPhone to computer without downloading USB driver of Apple mobile devices.
*Easily transfer and sync the files without search for the driver of the Apple mobile devices.
*Copy all or selected files from your iPad/iPod to any computer, and sync them to iTunes.Updated by Lily Stark to iPhoneFollow @Lily StarkOctober 30, 2018 07:10
This chapter provides a summary of USB device architecture and describes how USB devices are represented in OS X. It also presents a few specific guidelines for working with USB devices in an application.For details on the USB specification, see http://www.usb.org.USB Device Types and Bus Speeds
The USB specification supports a wide selection of devices that range from lower-speed devices such as keyboards, mice, and joysticks to higher-speed devices such as scanners and digital cameras. The specification lists a number of device classes that each define a set of expected device behaviors. Table 1-1 lists some examples of USB devices, categorized by class.Table 1-1 Examples of USB devices
USB device class
USB devices in class
Audio class
Speakers, microphones
Chip Card Interface Device Class
Smart cards, chip cards
Communication class
Speakerphone, modem
Composite class
A device in which all class-specific information is embedded in its interfaces
HID class
Keyboards, mice, joysticks, drawing tablets
Hub class
Hubs provide additional attachment points for USB devices
Mass storage class
Hard drives, flash memory readers, CD Read/Write drives, digital cameras, and high-end media players
Printing class
Printers
Vendor specific
A device that doesn’t fit into any other predefined class or one that doesn’t use the standard protocols for an existing class
Video class
Digital camcorders, webcams, digital still cameras that support video streaming
Version 1.1 of the USB specification supports two bus speeds:
*
Low speed (1.5 Mbps)
*
Full speed (12 Mbps)
Version 2.0 of the specification adds another bus speed to this list:
*
High speed (480 Mbps)
The USB 2.0 specification is fully compatible with low-speed and full-speed USB devices and even supports the use of cables and connectors made to meet earlier versions of the specification. Apple provides USB 2.0 ports on all new Macintosh computers and fully supports the new specification with Enhanced Host Controller Interface (EHCI) controllers and built-in, low-level USB drivers.
For the most part, you do not have to change existing applications to support the faster data rate because the speed increase and other enhancements are implemented at such a low level. The exceptions to this are some differences in isochronous transfers. For information on how the USB 2.0 specification affects isochronous transfers, see USB 2.0 and Isochronous Transfers.USB Device Architecture and Terminology
The architecture of a generic USB device is multi-layered. A device consists of one or more configurations, each of which describes a possible setting the device can be programmed into. Such settings can include the power characteristics of the configuration (for example, the maximum power consumed by the configuration and whether it is self-powered or not) and whether the configuration supports remote wake-up.
Each configuration contains one or more interfaces that are accessible after the configuration is set. An interface provides the definitions of the functions available within the device and may even contain alternate settings within a single interface. For example, an interface for an audio device may have different settings you can select for different bandwidths.
Each interface contains zero or more endpoints. An endpoint is a uniquely identifiable portion of a USB device that is the source or sink of information in a communication flow between the host and the device. Each endpoint has characteristics that describe the communication it supports, such as transfer type (control, isochronous, interrupt, or bulk, described in USB Transfer Types), maximum packet size, and transfer direction (input or output).
Communication with a USB device is accomplished through a pipe, a logical association between an endpoint and software running on the host. Endpoint and pipe are often used synonymously although an endpoint is a component of a USB device and a pipe is a logical abstraction of the communications link between endpoint and host.USB Device Component Descriptors
Each layer of a USB device provides information about its attributes and resource requirements in its descriptor, a data structure accessible through device interface functions. By examining the descriptors at each layer, you can determine exactly which endpoint you need to communicate successfully with a particular device.
At the top layer is the device descriptor, which has fields associated with information such as the device’s class and subclass, vendor and product numbers, and number of configurations. Each configuration in turn has a configuration descriptor containing fields that describe the number of interfaces it supports and the power characteristics of the device when it is in that configuration, along with other information. Each interface supported by a configuration has its own descriptor with fields for information such as the interface class, subclass, and protocol, and the number of endpoints in that interface. At the bottom layer are the endpoint descriptors that specify attributes such as transfer type and maximum packet size.
The USB specification defines a name for each descriptor field, such as the bDeviceClass field in the device descriptor and the bNumInterfaces field in the configuration descriptor, and each field is associated with a value. For a complete listing of all descriptor fields, see the USB specification at www.usb.org. The USB family defines structures that represent the descriptors defined by the USB specification. For the definitions of these structures, see USB in Kernel Framework Reference.USB Composite Class Devices
The USB specification defines a composite class device as a device whose device-descriptor fields for device class (bDeviceClass) and device subclass (bDeviceSubClass) both have the value 0. A composite class device appears to the system as a USB device using a single bus address that may present multiple interfaces, each of which represents a separate function. A good example of a composite class device is a multifunction device, such as a device that performs printing, scanning, and faxing. In such a device, each function is represented by a separate interface. In OS X, the I/O Kit loads the AppleUSBComposite device driver for composite class devices that do not already have vendor-specific device drivers to drive them. The AppleUSBComposite driver configures the device and causes drivers to be loaded for each USB interface.
Although most multifunction USB devices are composite class devices, not all composite class devices are multifunction devices. The manufacturer of a single-function USB device is at liberty to classify the device as a composite class device as long as the device meets the USB specifications. For more information on how OS X represents USB devices and interfaces, see USB Devices on OS X. USB Transfer Types
The USB specification defines four types of pipe transfer:
*
Control—intended to support configuration, command, and status communication between the host software and the device. Control transfers support error detection and retry.
*
Interrupt—used to support small, limited-latency transfers to or from a device such as coordinates from a pointing device or status changes from a modem. Interrupt transfers support error detection and retry.
*
Isochronous—used for periodic, continuous communication between the host and the device, usually involving time-relevant information such as audio or video data streams. Isochronous transfers do not support error detection or retry.
*
Bulk—intended for non-periodic, large-packet communication with relaxed timing constraints such as between the host software and a printer or scanner. Bulk transfers support error detection and retry.
Pipes also have a transfer direction associated with them. A control pipe can support bidirectional communication but all other pipes are strictly uni-directional. Therefore, two-way communication requires two pipes, one for input and one for output.
Every USB device is required to implement a default control pipe that provides access to the device’s configuration, status, and control information. This pipe, implemented in the IOUSBDevice nub object (described in USB Devices on OS X), is used when a driver such as the AppleUSBComposite driver configures the device or when device-specific control and status information is needed. For example, your application would use the default control pipe if it needs to set or choose a configuration for the device. The default control pipe is connected to the default endpoint (endpoint 0). Note that endpoint 0 does not provide an endpoint descriptor and it is never counted in the total number of endpoints in an interface.
The interfaces associated with a configuration can contain any combination of the three remaining pipe types (interrupt, isochronous, and bulk), implemented in the IOUSBInterface nub objects (described in USB Devices on OS X). Your application can query the interface descriptors of a device to select the pipe most suited to its needs.Stalls and Halts
Although a stall and a halt are different, they are closely related in their effect on data transmission. Halt is a feature of an endpoint and it can be set by either the host or the device itself in response to an error. A stall is a type of handshake packet an endpoint returns when it is unable to transmit or receive data or when its halt feature is set (the host never sends a stall packet). When an endpoint sends a stall packet, the host can halt the endpoint.
Depending on the precise circumstances and on how compliant the device is, the halt feature must be cleared in the host, the endpoint, or both before data transmission can resume. When the halt is cleared the data toggle bit, used to synchronize data transmission, is also reset (see Data Synchronization in Non-Isochronous Transfers for more information about the data toggle). For information on how to handle these conditions in your application, see Handling Stalls, Halts, and Data Toggle Resynchronization.Data Synchronization in Non-Isochronous Transfers
The USB specification defines a simple protocol to provide data synchronization across multiple packets for non-isochronous transfers (recall that isochronous transfers do not support error recovery or retry). The protocol is implemented by means of a data toggle bit in both the host and the endpoint which is synchronized at the start of a transaction (or when a reset occurs). The precise synchronization mechanism varies with the type of transfer; see the USB specification for details.
Both the host and the endpoint begin a transaction with their data toggle bits set to zero. In general, the entity receiving data toggles its data toggle bit when it is able to accept the data and it receives an error-free data packet with the correct identification. The entity sending the data toggles its data toggle bit when it receives a positive acknowledgement from the receiver. In this way, the data toggle bits stay synchronized until, for example, a packet with an incorrect identification is received. When this happens, the receiver ignores the packet and does not increment its data toggle bit. When the data toggle bits get out of synchronization (for this or any other reason), you will probably notice that alternate transactions are not getting through in your application. The solution to this is to resynchronize the data toggle bits. For information on how to do this, see Handling Stalls, Halts, and Data Toggle Resynchronization.USB 2.0 and Isochronous Transfers
The USB 2.0 specification supports the same four transfer types as earlier versions of the specification. In addition to supporting a higher transfer rate, the new specification defines an improved protocol for high-speed transfers and new ways of handling transactions for low-speed and full-speed devices. For details on the protocols and transaction-handling methods, see the specification at http://www.usb.org.
For the most part, these enhancements are implemented at the host software level and do not require changes to your code. For isochronous transfers, however, you should be aware of the following differences:
*
Earlier versions of the specification divide bus time into 1-millisecond frames, each of which can carry multiple transactions to multiple destinations. (A transaction contains two or more packets: a token packet and one or more data packets, a handshake packet, or both.) The USB 2.0 specification divides the 1-millisecond frame into eight, 125-microsecond microframes, each of which can carry multiple transactions to multiple destinations.
*
The maximum amount of data allowed in a transaction is increased to 3 KB.
*
Any isochronous endpoints in a device’s default interface must have a maximum packet size of zero. (This means that the default setting for an interface containing isochronous pipes is alternate setting zero and the maximum packet size for that interface’s isochronous endpoints must be zero.) This ensures that the host can configure the device no matter how busy the bus is.Apple Usb Driver
For a summary of how these differences affect the OS X USB API, see Changes in Isochronous Functions to Support USB 2.0.USB Devices on OS X
When a USB device is plugged in, the OS X USB family abstracts the contents of the device descriptor into an I/O Kit nub object called an IOUSBDevice. This nub object is attached to the IOService plane of the I/O Registry as a child of the driver for the USB controller. The IOUSBDevice nub object is then registered for matching with the I/O Kit.
If the device is a composite class device with no vendor-specific driver to match against it, the AppleUSBComposite driver matches against it and starts as its provider. The AppleUSBComposite driver then configures the device by setting the configuration in the device’s list of configuration descriptors with the maximum power usage that can be satisfied by the port to which the device is attached. This allows a device with a low power and a high power configuration to be configured differently depending on whether it’s attached to a bus-powered hub or a self-powered hub. In addition, if the IOUSBDevice nub object has the “Preferred Configuration” property, the AppleUSBComposite driver will always use that value when it attempts to configure the device.
The configuration of the device causes the USB family to abstract each interface descriptor in the chosen configuration into an IOUSBInterface nub object. These nub objects are attached to the I/O Registry as children of the original IOUSBDevice nub object and are registered for matching with the I/O Kit.
Important: Because a composite class device is configured by the AppleUSBComposite driver, setting the configuration again from your application will result in the destruction of the IOUSBInterface nub objects and the creation of new ones. In general, the only reason to set the configuration of a composite class device that’s matched by the AppleUSBComposite driver is to choose a configuration other than the first one.
For non-composite class devices or composite class devices with vendor-specific drivers that match against them, there is no guarantee that any configuration will be set and you may have to perform this task within your application.
It’s important to be mindful of the difference between a USB device (represented in the I/O Registry by an IOUSBDevi
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