Class: Lignite::Connection::Usb

Inherits:
Lignite::Connection show all
Includes:
Logger
Defined in:
lib/lignite/connection/usb.rb

Constant Summary collapse

VENDOR_LEGO =

To get to the endpoint we need to descend down the hierarchy of 1) Device

0x0694
PRODUCT_EV3 = 
5
CONFIGURATION_EV3 =

2) Configuration, 1-based

1
INTERFACE_EV3 =

3) Interface, 0-based

0
SETTING_EV3 =

4) Alternate setting, 0-based

0
ENDPOINT_EV3 =

5) Endpoint, 0-based

1

Instance Attribute Summary collapse

Instance Method Summary collapse

Methods included from Logger

default_logger, #logger

Methods inherited from Lignite::Connection

create

Constructor Details

#initialize ⇒ Usb

Returns a new instance of Usb.

Raises:



27
28
29
30
31
32
33
34
35
36
37
38
 
# File 'lib/lignite/connection/usb.rb', line 27

def initialize
  usb = LIBUSB::Context.new
  @device = usb.devices(idVendor: VENDOR_LEGO, idProduct: PRODUCT_EV3).first
  raise Lignite::NoUsbDevice if @device.nil?

  ## Because multiple configs are rare, the library allows to omit this:
  ## device.set_configuration(CONFIGURATION_EV3)
  @interface = @device.interfaces[INTERFACE_EV3]
  eps = @interface.endpoints
  @out_ep = eps.find { |e| e.direction == :out}
  @in_ep = eps.find { |e| e.direction == :in}
end

Instance Attribute Details

#device ⇒ Object (readonly)

Returns the value of attribute device.



25
26
27
 
# File 'lib/lignite/connection/usb.rb', line 25

def device
  @device
end

#in_ep ⇒ Object (readonly)

Returns the value of attribute in_ep.



25
26
27
 
# File 'lib/lignite/connection/usb.rb', line 25

def in_ep
  @in_ep
end

#interface ⇒ Object (readonly)

Returns the value of attribute interface.



25
26
27
 
# File 'lib/lignite/connection/usb.rb', line 25

def interface
  @interface
end

#out_ep ⇒ Object (readonly)

Returns the value of attribute out_ep.



25
26
27
 
# File 'lib/lignite/connection/usb.rb', line 25

def out_ep
  @out_ep
end

Instance Method Details

#read(bytes = nil) ⇒ String

Returns:

  • (String) 


53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
 
# File 'lib/lignite/connection/usb.rb', line 53

def read(bytes = nil)
  got = nil
  @device.open do |devh|
    devh.auto_detach_kernel_driver = true
    devh.claim_interface(@interface) do
      begin
        got = devh.interrupt_transfer(endpoint: @in_ep, dataIn: bytes)
      rescue LIBUSB::Error => e
        if e.transferred.is_a? String
          got = e.transferred
        else
          raise
        end
      end
    end
  end
  logger.debug "Read returning #{got.bytesize} bytes"
  got
end

#write(data) ⇒ Integer

Returns number of bytes written.

Returns:

  • (Integer) —

    number of bytes written



41
42
43
44
45
46
47
48
49
50
 
# File 'lib/lignite/connection/usb.rb', line 41

def write(data)
  written = nil
  @device.open do |devh|
    devh.auto_detach_kernel_driver = true
    devh.claim_interface(@interface) do
      written = devh.interrupt_transfer(endpoint: @out_ep, dataOut: data)
    end
  end
  written
end