Class: LIBUSB::DevHandle

Inherits:
Object
  • Object
show all
Defined in:
lib/libusb/dev_handle.rb

Overview

Class representing a handle on a USB device.

A device handle is used to perform I/O and other operations. When finished with a device handle, you should call DevHandle#close .

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(device, pHandle) ⇒ DevHandle

Returns a new instance of DevHandle.



29
30
31
32
33
 
# File 'lib/libusb/dev_handle.rb', line 29

def initialize device, pHandle
  @device = device
  @pHandle = pHandle
  @bulk_transfer = @control_transfer = @interrupt_transfer = nil
end

Instance Attribute Details

#device ⇒ Device (readonly)

Returns the device this handle belongs to.

Returns:

  • (Device) —

    the device this handle belongs to.



27
28
29
 
# File 'lib/libusb/dev_handle.rb', line 27

def device
  @device
end

Instance Method Details

#attach_kernel_driver(interface) ⇒ Object

Re-attach an interface’s kernel driver, which was previously detached using #detach_kernel_driver.

Parameters:

  • interface (Interface, Fixnum) —

    the interface to attach the driver to



222
223
224
225
226
 
# File 'lib/libusb/dev_handle.rb', line 222

def attach_kernel_driver(interface)
  interface = interface.bInterfaceNumber if interface.respond_to? :bInterfaceNumber
  res = Call.libusb_attach_kernel_driver(@pHandle, interface)
  LIBUSB.raise_error res, "in libusb_attach_kernel_driver" if res!=0
end

#bulk_transfer(args = {}) ⇒ Fixnum, String

Perform a USB bulk transfer.

The direction of the transfer is inferred from the direction bits of the endpoint address.

For bulk reads, the :dataIn param indicates the maximum length of data you are expecting to receive. If less data arrives than expected, this function will return that data.

You should also check the returned number of bytes for bulk writes. Not all of the data may have been written.

Also check transferred bytes when dealing with a timeout error code. libusb may have to split your transfer into a number of chunks to satisfy underlying O/S requirements, meaning that the timeout may expire after the first few chunks have completed. libusb is careful not to lose any data that may have been transferred; do not assume that timeout conditions indicate a complete lack of I/O.

Parameters:

  • :endpoint (Endpoint, Fixnum) —

    the (address of a) valid endpoint to communicate with

  • :dataOut (String) —

    the data to send with an outgoing transfer

  • :dataIn (Fixnum) —

    the number of bytes expected to receive with an ingoing transfer

  • :timeout (Fixnum) —

    timeout (in millseconds) that this function should wait before giving up due to no response being received. For an unlimited timeout, use value 0. Defaults to 1000 ms.

Returns:

  • (Fixnum) —

    Number of bytes sent for an outgoing transfer

  • (String) —

    Received data for an ingoing transfer

Raises:

  • (ArgumentError) 


256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
 
# File 'lib/libusb/dev_handle.rb', line 256

def bulk_transfer(args={})
  timeout = args.delete(:timeout) || 1000
  endpoint = args.delete(:endpoint) || raise(ArgumentError, "no endpoint given")
  endpoint = endpoint.bEndpointAddress if endpoint.respond_to? :bEndpointAddress
  if endpoint&ENDPOINT_IN != 0
    dataIn = args.delete(:dataIn) || raise(ArgumentError, "no :dataIn given for bulk read")
  else
    dataOut = args.delete(:dataOut) || raise(ArgumentError, "no :dataOut given for bulk write")
  end
  raise ArgumentError, "invalid params #{args.inspect}" unless args.empty?

  # reuse transfer struct to speed up transfer
  @bulk_transfer ||= BulkTransfer.new :dev_handle => self
  tr = @bulk_transfer
  tr.endpoint = endpoint
  tr.timeout = timeout
  if dataOut
    tr.buffer = dataOut
  else
    tr.alloc_buffer(dataIn)
  end

  tr.submit_and_wait!

  if dataOut
    tr.actual_length
  else
    tr.actual_buffer
  end
end

#claim_interface(interface) ⇒ Object

Claim an interface on a given device handle.

You must claim the interface you wish to use before you can perform I/O on any of its endpoints.

It is legal to attempt to claim an already-claimed interface, in which case libusb just returns without doing anything.

Claiming of interfaces is a purely logical operation; it does not cause any requests to be sent over the bus. Interface claiming is used to instruct the underlying operating system that your application wishes to take ownership of the interface.

This is a non-blocking function.

If called with a block, the device handle is passed through to the block and the interface is released when the block has finished.

Parameters:

  • interface (Interface, Fixnum) —

    the interface or it’s bInterfaceNumber you wish to claim



73
74
75
76
77
78
79
80
81
82
83
 
# File 'lib/libusb/dev_handle.rb', line 73

def claim_interface(interface)
  interface = interface.bInterfaceNumber if interface.respond_to? :bInterfaceNumber
  res = Call.libusb_claim_interface(@pHandle, interface)
  LIBUSB.raise_error res, "in libusb_claim_interface" if res!=0
  return self unless block_given?
  begin
    yield self
  ensure
    release_interface(interface)
  end
end

#clear_halt(endpoint) ⇒ Object

Clear the halt/stall condition for an endpoint.

Endpoints with halt status are unable to receive or transmit data until the halt condition is stalled.

You should cancel all pending transfers before attempting to clear the halt condition.

This is a blocking function.

Parameters:

  • endpoint (Endpoint, Fixnum) —

    the endpoint in question or it’s bEndpointAddress



169
170
171
172
173
 
# File 'lib/libusb/dev_handle.rb', line 169

def clear_halt(endpoint)
  endpoint = endpoint.bEndpointAddress if endpoint.respond_to? :bEndpointAddress
  res = Call.libusb_clear_halt(@pHandle, endpoint)
  LIBUSB.raise_error res, "in libusb_clear_halt" if res!=0
end

#close ⇒ Object

Close a device handle.

Should be called on all open handles before your application exits.

Internally, this function destroys the reference that was added by LIBUSB::Device#open on the given device.

This is a non-blocking function; no requests are sent over the bus.



43
44
45
 
# File 'lib/libusb/dev_handle.rb', line 43

def close
  Call.libusb_close(@pHandle)
end

#control_transfer(args = {}) ⇒ Fixnum, String

Perform a USB control transfer.

The direction of the transfer is inferred from the :bmRequestType field of the setup packet.

Parameters:

  • :bmRequestType (Fixnum) —

    the request type field for the setup packet

  • :bRequest (Fixnum) —

    the request field for the setup packet

  • :wValue (Fixnum) —

    the value field for the setup packet

  • :wIndex (Fixnum) —

    the index field for the setup packet

  • :dataOut (String) —

    the data to send with an outgoing transfer, it is appended to the setup packet

  • :dataIn (Fixnum) —

    the number of bytes expected to receive with an ingoing transfer (excluding setup packet)

  • :timeout (Fixnum) —

    timeout (in millseconds) that this function should wait before giving up due to no response being received. For an unlimited timeout, use value 0. Defaults to 1000 ms.

Returns:

  • (Fixnum) —

    Number of bytes sent (excluding setup packet) for outgoing transfer

  • (String) —

    Received data (without setup packet) for ingoing transfer

Raises:

  • (ArgumentError) 


365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
 
# File 'lib/libusb/dev_handle.rb', line 365

def control_transfer(args={})
  bmRequestType = args.delete(:bmRequestType) || raise(ArgumentError, "param :bmRequestType not given")
  bRequest = args.delete(:bRequest) || raise(ArgumentError, "param :bRequest not given")
  wValue = args.delete(:wValue) || raise(ArgumentError, "param :wValue not given")
  wIndex = args.delete(:wIndex) || raise(ArgumentError, "param :wIndex not given")
  timeout = args.delete(:timeout) || 1000
  if bmRequestType&ENDPOINT_IN != 0
    dataIn = args.delete(:dataIn) || 0
    dataOut = ''
  else
    dataOut = args.delete(:dataOut) || ''
  end
  raise ArgumentError, "invalid params #{args.inspect}" unless args.empty?

  # reuse transfer struct to speed up transfer
  @control_transfer ||= ControlTransfer.new :dev_handle => self
  tr = @control_transfer
  tr.timeout = timeout
  if dataIn
    setup_data = [bmRequestType, bRequest, wValue, wIndex, dataIn].pack('CCvvv')
    tr.alloc_buffer( dataIn + CONTROL_SETUP_SIZE, setup_data )
  else
    tr.buffer = [bmRequestType, bRequest, wValue, wIndex, dataOut.bytesize, dataOut].pack('CCvvva*')
  end

  tr.submit_and_wait!

  if dataIn
    tr.actual_buffer(CONTROL_SETUP_SIZE)
  else
    tr.actual_length
  end
end

#detach_kernel_driver(interface) ⇒ Object

Detach a kernel driver from an interface.

If successful, you will then be able to claim the interface and perform I/O.

Parameters:

  • interface (Interface, Fixnum) —

    the interface to detach the driver from or it’s bInterfaceNumber



212
213
214
215
216
 
# File 'lib/libusb/dev_handle.rb', line 212

def detach_kernel_driver(interface)
  interface = interface.bInterfaceNumber if interface.respond_to? :bInterfaceNumber
  res = Call.libusb_detach_kernel_driver(@pHandle, interface)
  LIBUSB.raise_error res, "in libusb_detach_kernel_driver" if res!=0
end

#interrupt_transfer(args = {}) ⇒ Fixnum, String

Perform a USB interrupt transfer.

The direction of the transfer is inferred from the direction bits of the endpoint address.

For interrupt reads, the :dataIn param indicates the maximum length of data you are expecting to receive. If less data arrives than expected, this function will return that data.

You should also check the returned number of bytes for interrupt writes. Not all of the data may have been written.

Also check transferred when dealing with a timeout error code. libusb may have to split your transfer into a number of chunks to satisfy underlying O/S requirements, meaning that the timeout may expire after the first few chunks have completed. libusb is careful not to lose any data that may have been transferred; do not assume that timeout conditions indicate a complete lack of I/O.

The default endpoint bInterval value is used as the polling interval.

Parameters:

  • :endpoint (Endpoint, Fixnum) —

    the (address of a) valid endpoint to communicate with

  • :dataOut (String) —

    the data to send with an outgoing transfer

  • :dataIn (Fixnum) —

    the number of bytes expected to receive with an ingoing transfer

  • :timeout (Fixnum) —

    timeout (in millseconds) that this function should wait before giving up due to no response being received. For an unlimited timeout, use value 0. Defaults to 1000 ms.

Returns:

  • (Fixnum) —

    Number of bytes sent for an outgoing transfer

  • (String) —

    Received data for an ingoing transfer

Raises:

  • (ArgumentError) 


316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
 
# File 'lib/libusb/dev_handle.rb', line 316

def interrupt_transfer(args={})
  timeout = args.delete(:timeout) || 1000
  endpoint = args.delete(:endpoint) || raise(ArgumentError, "no endpoint given")
  endpoint = endpoint.bEndpointAddress if endpoint.respond_to? :bEndpointAddress
  if endpoint&ENDPOINT_IN != 0
    dataIn = args.delete(:dataIn) || raise(ArgumentError, "no :dataIn given for interrupt read")
  else
    dataOut = args.delete(:dataOut) || raise(ArgumentError, "no :dataOut given for interrupt write")
  end
  raise ArgumentError, "invalid params #{args.inspect}" unless args.empty?

  # reuse transfer struct to speed up transfer
  @interrupt_transfer ||= InterruptTransfer.new :dev_handle => self
  tr = @interrupt_transfer
  tr.endpoint = endpoint
  tr.timeout = timeout
  if dataOut
    tr.buffer = dataOut
  else
    tr.alloc_buffer(dataIn)
  end

  tr.submit_and_wait!

  if dataOut
    tr.actual_length
  else
    tr.actual_buffer
  end
end

#kernel_driver_active?(interface) ⇒ Boolean

Determine if a kernel driver is active on an interface.

If a kernel driver is active, you cannot claim the interface, and libusb will be unable to perform I/O.

Parameters:

  • interface (Interface, Fixnum) —

    the interface to check or it’s bInterfaceNumber

Returns:

  • (Boolean) 


199
200
201
202
203
204
 
# File 'lib/libusb/dev_handle.rb', line 199

def kernel_driver_active?(interface)
  interface = interface.bInterfaceNumber if interface.respond_to? :bInterfaceNumber
  res = Call.libusb_kernel_driver_active(@pHandle, interface)
  LIBUSB.raise_error res, "in libusb_kernel_driver_active" unless res>=0
  return res==1
end

#release_interface(interface) ⇒ Object

Release an interface previously claimed with #claim_interface.

You should release all claimed interfaces before closing a device handle.

This is a blocking function. A SET_INTERFACE control request will be sent to the device, resetting interface state to the first alternate setting.

Parameters:

  • interface (Interface, Fixnum) —

    the interface or it’s bInterfaceNumber you claimed previously



94
95
96
97
98
 
# File 'lib/libusb/dev_handle.rb', line 94

def release_interface(interface)
  interface = interface.bInterfaceNumber if interface.respond_to? :bInterfaceNumber
  res = Call.libusb_release_interface(@pHandle, interface)
  LIBUSB.raise_error res, "in libusb_release_interface" if res!=0
end

#reset_device ⇒ Object

Perform a USB port reset to reinitialize a device.

The system will attempt to restore the previous configuration and alternate settings after the reset has completed.

If the reset fails, the descriptors change, or the previous state cannot be restored, the device will appear to be disconnected and reconnected. This means that the device handle is no longer valid (you should close it) and rediscover the device. A Exception of LIBUSB::ERROR_NOT_FOUND indicates when this is the case.

This is a blocking function which usually incurs a noticeable delay.



187
188
189
190
 
# File 'lib/libusb/dev_handle.rb', line 187

def reset_device
  res = Call.libusb_reset_device(@pHandle)
  LIBUSB.raise_error res, "in libusb_reset_device" if res!=0
end

#set_configuration(configuration) ⇒ Object Also known as: configuration=

Set the active configuration for a device.

The operating system may or may not have already set an active configuration on the device. It is up to your application to ensure the correct configuration is selected before you attempt to claim interfaces and perform other operations.

If you call this function on a device already configured with the selected configuration, then this function will act as a lightweight device reset: it will issue a SET_CONFIGURATION request using the current configuration, causing most USB-related device state to be reset (altsetting reset to zero, endpoint halts cleared, toggles reset).

You cannot change/reset configuration if your application has claimed interfaces - you should free them with #release_interface first. You cannot change/reset configuration if other applications or drivers have claimed interfaces.

A configuration value of nil will put the device in unconfigured state. The USB specifications state that a configuration value of 0 does this, however buggy devices exist which actually have a configuration 0.

You should always use this function rather than formulating your own SET_CONFIGURATION control request. This is because the underlying operating system needs to know when such changes happen.

This is a blocking function.

Parameters:

  • configuration (Configuration, Fixnum) —

    the configuration or it’s bConfigurationValue you wish to activate, or nil if you wish to put the device in unconfigured state



130
131
132
133
134
 
# File 'lib/libusb/dev_handle.rb', line 130

def set_configuration(configuration)
  configuration = configuration.bConfigurationValue if configuration.respond_to? :bConfigurationValue
  res = Call.libusb_set_configuration(@pHandle, configuration || -1)
  LIBUSB.raise_error res, "in libusb_set_configuration" if res!=0
end

#set_interface_alt_setting(setting_or_interface_number, alternate_setting = nil) ⇒ Object

Activate an alternate setting for an interface.

The interface must have been previously claimed with #claim_interface.

You should always use this function rather than formulating your own SET_INTERFACE control request. This is because the underlying operating system needs to know when such changes happen.

This is a blocking function.

Parameters:

  • setting_or_interface_number (Setting, Fixnum) —

    the alternate setting to activate or the bInterfaceNumber of the previously-claimed interface

  • alternate_setting (Fixnum, nil) (defaults to: nil) —

    the bAlternateSetting of the alternate setting to activate (only if first param is a Fixnum)



151
152
153
154
155
156
 
# File 'lib/libusb/dev_handle.rb', line 151

def set_interface_alt_setting(setting_or_interface_number, alternate_setting=nil)
  alternate_setting ||= setting_or_interface_number.bAlternateSetting if setting_or_interface_number.respond_to? :bAlternateSetting
  setting_or_interface_number = setting_or_interface_number.bInterfaceNumber if setting_or_interface_number.respond_to? :bInterfaceNumber
  res = Call.libusb_set_interface_alt_setting(@pHandle, setting_or_interface_number, alternate_setting)
  LIBUSB.raise_error res, "in libusb_set_interface_alt_setting" if res!=0
end

#string_descriptor_ascii(index) ⇒ Object 



47
48
49
50
51
52
 
# File 'lib/libusb/dev_handle.rb', line 47

def string_descriptor_ascii(index)
  pString = FFI::MemoryPointer.new 0x100
  res = Call.libusb_get_string_descriptor_ascii(@pHandle, index, pString, pString.size)
  LIBUSB.raise_error res, "in libusb_get_string_descriptor_ascii" unless res>=0
  pString.read_string(res)
end