使用PyUSB usb.util.Get_string（）获取字符串描述符

Question

我无法获取USB设备的字符串描述符。我要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，因此我知道它存在。

PyUSB帮助文件指出，可以使用以下方法访问usb_get_string_simple（从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

任何帮助都将不胜感激。

Answer 1

硬编码索引不是个好主意。

我建议你用这样的方法：

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

如下所示，每个设备的索引都不同。

lsusb-v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

Answer 2

（更新日期：2019年7月：请参阅下面的Teodor Bogdan Barbieru的答案，以获得不应实际硬编码索引的明确说明！）

（2019年7月第二次更新：有关USB规范的链接（包含列出所有设备描述符字段的表），请参阅下面的gog注释。）

代码中的以下行：

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

确实是个问题。我不太清楚USB规范说明了什么，但在我当前的硬件项目中，我得到了以下索引选项：

• index=0（您可以选择）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，试着：

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

祝你好运！

Answer 3

这将从设备中检索字符串：

dev = usb.core.find(idVendor=0x077d, idProduct=0x0410) # fill in your own device, of course
if dev is None:
    print 'Our device is not connected'
else:
    if dev._manufacturer is None:
        dev._manufacturer = usb.util.get_string(dev, dev.iManufacturer)
    print str(dev._manufacturer)
    if dev._product is None:
        dev._product = usb.util.get_string(dev, dev.iProduct)
    print str(dev._product)