使用PyUSB获取字符串描述符usb.util.get_string()

Question

我无法获取USB设备的字符串描述符.我正在寻找的是人性化的制造商和产品名称.我使用libusb-1.0作为后端,并且能够使用提供的libusb测试程序获取制造商名称,所以我知道它存在.

PyUSB帮助文件说你可以使用以下方法访问usb_get_string_simple(来自libusb后端):

get_string(dev,length,index,langid = None)

   Retrieve a string descriptor from the device.
   dev is the Device object to which the request will be sent to.

   length is the length of string in number of characters.

   index is the string descriptor index and langid is the Language
   ID of the descriptor. If langid is omitted, the string descriptor
   of the first Language ID will be returned.

   The return value is the unicode string present in the descriptor.

import usb
#help(usb.core) 
busses = usb.busses()
for bus in busses:
  devices = bus.devices
  for dev in devices:
    _name = usb.util.get_string(dev.dev,256,0)  #This is where I'm having trouble
    print "device name=",_name
    print "Device:", dev.filename
    print "  Device class:",dev.deviceClass
    print "  Device sub class:",dev.deviceSubClass
    print "  Device protocol:",dev.deviceProtocol
    print "  Max packet size:",dev.maxPacketSize
    print "  idVendor:",hex(dev.idVendor)
    print "  idProduct:",hex(dev.idProduct)
    print "  Device Version:",dev.deviceVersion
    for config in dev.configurations:
      print "  Configuration:", config.value
      print "    Total length:", config.totalLength 
      print "    selfPowered:", config.selfPowered
      print "    remoteWakeup:", config.remoteWakeup
      print "    maxPower:", config.maxPower
      for intf in config.interfaces:
        print "    Interface:",intf[0].interfaceNumber
        for alt in intf:
          print "    Alternate Setting:",alt.alternateSetting
          print "      Interface class:",alt.interfaceClass
          print "      Interface sub class:",alt.interfaceSubClass
          print "      Interface protocol:",alt.interfaceProtocol
          for ep in alt.endpoints:
            print "      Endpoint:",hex(ep.address)
            print "        Type:",ep.type
            print "        Max packet size:",ep.maxPacketSize
            print "        Interval:",ep.interval

任何帮助将不胜感激.

Answer 1

代码中的以下行:

usb.util.get_string(dev.dev,256,0)

确实是问题所在.我并不十分清楚USB规范说的是什么,但在我目前的硬件项目中,我得到以下选择索引:

• index = 0(您的选择)返回单个unicode字符
• index = 1发送制造商
• index = 2发送设备描述
• index = 3发送设备序列号

所以,试试:

usb.util.get_string(dev.dev, 256, 2)

祝好运!

Answer 2

对索引进行硬编码不是一个好主意。

我会建议使用这样的东西：

usb.util.get_string(dev, 256, dev.iSerialNumber)
usb.util.get_string(dev, 256, dev.iManufacturer)

正如您将在下面看到的，索引因设备而异。

lsusb -v 的输出：

device 1:            #index #string_descriptor
      iManufacturer  3 Linux 3.8.13 musb-hcd
      iProduct       2 MUSB HDRC host driver
      iSerial        1 musb-hdrc.1.auto

device 2:
      iManufacturer  2 E-boda
      iProduct       3 SUNNY V35
      iSerial        4 0123456789ABCDEF