UsbDeviceConnection
open class UsbDeviceConnection
| kotlin.Any | |
| ↳ | android.hardware.usb.UsbDeviceConnection |
This class is used for sending and receiving data and control messages to a USB device. Instances of this class are created by UsbManager.openDevice.
Summary
| Public methods | |
|---|---|
| open Int |
bulkTransfer(endpoint: UsbEndpoint!, buffer: ByteArray!, length: Int, timeout: Int)Performs a bulk transaction on the given endpoint. |
| open Int |
bulkTransfer(endpoint: UsbEndpoint!, buffer: ByteArray!, offset: Int, length: Int, timeout: Int)Performs a bulk transaction on the given endpoint. |
| open Boolean |
claimInterface(intf: UsbInterface!, force: Boolean)Claims exclusive access to a |
| open Unit |
close()Releases all system resources related to the device. |
| open Int |
controlTransfer(requestType: Int, request: Int, value: Int, index: Int, buffer: ByteArray?, length: Int, timeout: Int)Performs a control transaction on endpoint zero for this device. |
| open Int |
controlTransfer(requestType: Int, request: Int, value: Int, index: Int, buffer: ByteArray?, offset: Int, length: Int, timeout: Int)Performs a control transaction on endpoint zero for this device. |
| open Int |
Returns the native file descriptor for the device, or -1 if the device is not opened. |
| open ByteArray! |
Returns the raw USB descriptors for the device. |
| open String! |
Returns the serial number for the device. |
| open Boolean |
releaseInterface(intf: UsbInterface!)Releases exclusive access to a |
| open UsbRequest! |
Waits for the result of a android. |
| open UsbRequest! |
requestWait(timeout: Long)Waits for the result of a android. |
| open Boolean |
setConfiguration(configuration: UsbConfiguration!)Sets the device's current |
| open Boolean |
setInterface(intf: UsbInterface!)Sets the current |
| Protected methods | |
|---|---|
| open Unit |
finalize()Called by the garbage collector on an object when garbage collection determines that there are no more references to the object. |
Public methods
bulkTransfer
open fun bulkTransfer(
endpoint: UsbEndpoint!,
buffer: ByteArray!,
length: Int,
timeout: Int
): Int
Performs a bulk transaction on the given endpoint. The direction of the transfer is determined by the direction of the endpoint.
This method transfers data starting from index 0 in the buffer. To specify a different offset, use bulkTransfer(android.hardware.usb.UsbEndpoint,byte[],int,int,int).
| Parameters | |
|---|---|
endpoint |
UsbEndpoint!: the endpoint for this transaction |
buffer |
ByteArray!: buffer for data to send or receive; can be null to wait for next transaction without reading data |
length |
Int: the length of the data to send or receive. Before {@value android.os.Build.VERSION_CODES#P Build.VERSION_CODES.P}, a value larger than 16384 bytes would be truncated down to 16384. In API {@value android.os.Build.VERSION_CODES#P Build.VERSION_CODES.P} and after, any value of length is valid. |
timeout |
Int: in milliseconds, 0 is infinite |
| Return | |
|---|---|
Int |
length of data transferred (or zero) for success, or negative value for failure |
bulkTransfer
open fun bulkTransfer(
endpoint: UsbEndpoint!,
buffer: ByteArray!,
offset: Int,
length: Int,
timeout: Int
): Int
Performs a bulk transaction on the given endpoint. The direction of the transfer is determined by the direction of the endpoint.
| Parameters | |
|---|---|
endpoint |
UsbEndpoint!: the endpoint for this transaction |
buffer |
ByteArray!: buffer for data to send or receive |
offset |
Int: the index of the first byte in the buffer to send or receive |
length |
Int: the length of the data to send or receive. Before {@value android.os.Build.VERSION_CODES#P Build.VERSION_CODES.P}, a value larger than 16384 bytes would be truncated down to 16384. In API {@value android.os.Build.VERSION_CODES#P Build.VERSION_CODES.P} and after, any value of length is valid. |
timeout |
Int: in milliseconds, 0 is infinite |
| Return | |
|---|---|
Int |
length of data transferred (or zero) for success, or negative value for failure |
claimInterface
open fun claimInterface(
intf: UsbInterface!,
force: Boolean
): Boolean
Claims exclusive access to a android.hardware.usb.UsbInterface. This must be done before sending or receiving data on any android.hardware.usb.UsbEndpoints belonging to the interface.
| Parameters | |
|---|---|
intf |
UsbInterface!: the interface to claim |
force |
Boolean: true to disconnect kernel driver if necessary |
| Return | |
|---|---|
Boolean |
true if the interface was successfully claimed |
close
open fun close(): Unit
Releases all system resources related to the device. Once the object is closed it cannot be used again. The client must call UsbManager.openDevice again to retrieve a new instance to reestablish communication with the device.
controlTransfer
open fun controlTransfer(
requestType: Int,
request: Int,
value: Int,
index: Int,
buffer: ByteArray?,
length: Int,
timeout: Int
): Int
Performs a control transaction on endpoint zero for this device. The direction of the transfer is determined by the request type. If requestType & UsbConstants.USB_ENDPOINT_DIR_MASK is UsbConstants.USB_DIR_OUT, then the transfer is a write, and if it is UsbConstants.USB_DIR_IN, then the transfer is a read.
This method transfers data starting from index 0 in the buffer. To specify a different offset, use controlTransfer(int,int,int,int,byte[],int,int,int).
| Parameters | |
|---|---|
requestType |
Int: request type for this transaction |
request |
Int: request ID for this transaction |
value |
Int: value field for this transaction |
index |
Int: index field for this transaction |
buffer |
ByteArray?: buffer for data portion of transaction, or null if no data needs to be sent or received |
length |
Int: the length of the data to send or receive |
timeout |
Int: in milliseconds |
| Return | |
|---|---|
Int |
length of data transferred (or zero) for success, or negative value for failure |
controlTransfer
open fun controlTransfer(
requestType: Int,
request: Int,
value: Int,
index: Int,
buffer: ByteArray?,
offset: Int,
length: Int,
timeout: Int
): Int
Performs a control transaction on endpoint zero for this device. The direction of the transfer is determined by the request type. If requestType & UsbConstants.USB_ENDPOINT_DIR_MASK is UsbConstants.USB_DIR_OUT, then the transfer is a write, and if it is UsbConstants.USB_DIR_IN, then the transfer is a read.
| Parameters | |
|---|---|
requestType |
Int: request type for this transaction |
request |
Int: request ID for this transaction |
value |
Int: value field for this transaction |
index |
Int: index field for this transaction |
buffer |
ByteArray?: buffer for data portion of transaction, or null if no data needs to be sent or received |
offset |
Int: the index of the first byte in the buffer to send or receive |
length |
Int: the length of the data to send or receive |
timeout |
Int: in milliseconds |
| Return | |
|---|---|
Int |
length of data transferred (or zero) for success, or negative value for failure |
getFileDescriptor
open fun getFileDescriptor(): Int
Returns the native file descriptor for the device, or -1 if the device is not opened. This is intended for passing to native code to access the device.
| Return | |
|---|---|
Int |
the native file descriptor |
getRawDescriptors
open fun getRawDescriptors(): ByteArray!
Returns the raw USB descriptors for the device. This can be used to access descriptors not supported directly via the higher level APIs.
| Return | |
|---|---|
ByteArray! |
raw USB descriptors |
getSerial
open fun getSerial(): String!
Returns the serial number for the device. This will return null if the device has not been opened.
| Return | |
|---|---|
String! |
the device serial number |
releaseInterface
open fun releaseInterface(intf: UsbInterface!): Boolean
Releases exclusive access to a android.hardware.usb.UsbInterface.
| Return | |
|---|---|
Boolean |
true if the interface was successfully released |
requestWait
open fun requestWait(): UsbRequest!
Waits for the result of a android.hardware.usb.UsbRequest#queue operation
Note that this may return requests queued on multiple android.hardware.usb.UsbEndpoints. When multiple endpoints are in use, android.hardware.usb.UsbRequest#getEndpoint and android.hardware.usb.UsbRequest#getClientData can be useful in determining how to process the result of this function.
| Return | |
|---|---|
UsbRequest! |
a completed USB request, or null if an error occurred |
| Exceptions | |
|---|---|
java.lang.IllegalArgumentException |
Before API {@value android.os.Build.VERSION_CODES#O Build.VERSION_CODES.O}: if the number of bytes read or written is more than the limit of the request's buffer. The number of bytes is determined by the length parameter of UsbRequest.queue(ByteBuffer, int) |
java.nio.BufferOverflowException |
In API {@value android.os.Build.VERSION_CODES#O Build.VERSION_CODES.O} and after: if the number of bytes read or written is more than the limit of the request's buffer. The number of bytes is determined by the length parameter of UsbRequest.queue(ByteBuffer, int) |
requestWait
open fun requestWait(timeout: Long): UsbRequest!
Waits for the result of a android.hardware.usb.UsbRequest#queue operation
Note that this may return requests queued on multiple android.hardware.usb.UsbEndpoints. When multiple endpoints are in use, android.hardware.usb.UsbRequest#getEndpoint and android.hardware.usb.UsbRequest#getClientData can be useful in determining how to process the result of this function.
Android processes UsbRequests asynchronously. Hence it is not guaranteed that requestWait(0) returns a request that has been queued right before even if the request could have been processed immediately.
| Parameters | |
|---|---|
timeout |
Long: timeout in milliseconds. If 0 this method does not wait. |
| Return | |
|---|---|
UsbRequest! |
a completed USB request, or null if an error occurred |
| Exceptions | |
|---|---|
java.nio.BufferOverflowException |
if the number of bytes read or written is more than the limit of the request's buffer. The number of bytes is determined by the length parameter of UsbRequest.queue(ByteBuffer, int) |
java.util.concurrent.TimeoutException |
if no request was received in timeout milliseconds. |
setConfiguration
open fun setConfiguration(configuration: UsbConfiguration!): Boolean
Sets the device's current android.hardware.usb.UsbConfiguration.
| Return | |
|---|---|
Boolean |
true if the configuration was successfully set |
setInterface
open fun setInterface(intf: UsbInterface!): Boolean
Sets the current android.hardware.usb.UsbInterface. Used to select between two interfaces with the same ID but different alternate setting.
| Return | |
|---|---|
Boolean |
true if the interface was successfully selected |
Protected methods
finalize
protected open fun finalize(): Unit
Called by the garbage collector on an object when garbage collection determines that there are no more references to the object. A subclass overrides the finalize method to dispose of system resources or to perform other cleanup.
The general contract of finalize is that it is invoked if and when the Java virtual machine has determined that there is no longer any means by which this object can be accessed by any thread that has not yet died, except as a result of an action taken by the finalization of some other object or class which is ready to be finalized. The finalize method may take any action, including making this object available again to other threads; the usual purpose of finalize, however, is to perform cleanup actions before the object is irrevocably discarded. For example, the finalize method for an object that represents an input/output connection might perform explicit I/O transactions to break the connection before the object is permanently discarded.
The finalize method of class Object performs no special action; it simply returns normally. Subclasses of Object may override this definition.
The Java programming language does not guarantee which thread will invoke the finalize method for any given object. It is guaranteed, however, that the thread that invokes finalize will not be holding any user-visible synchronization locks when finalize is invoked. If an uncaught exception is thrown by the finalize method, the exception is ignored and finalization of that object terminates.
After the finalize method has been invoked for an object, no further action is taken until the Java virtual machine has again determined that there is no longer any means by which this object can be accessed by any thread that has not yet died, including possible actions by other objects or classes which are ready to be finalized, at which point the object may be discarded.
The finalize method is never invoked more than once by a Java virtual machine for any given object.
Any exception thrown by the finalize method causes the finalization of this object to be halted, but is otherwise ignored.
| Exceptions | |
|---|---|
java.lang.Throwable |
the Exception raised by this method |