Python，evdev，usb条形码阅读器：如何解码输入的d

Question

我有Datalogic Gryphon GFS4400二维条码扫描仪。我已经把树莓皮和它的工作作为USB HID设备。我可以读取条形码，输出为默认TTY。在

我想创建一个在读取条形码时处理输出的服务。我正在使用python和evdev。在

有人能告诉我如何将输出转换为正确的字符吗？

Python脚本如下所示：

from evdev import InputDevice, categorize, ecodes

device = InputDevice("/dev/input/by-id/usb-Datalogic_ADC__Inc._Handheld_Barcode_Scanner_S_N_G17A58010-event-kbd") # my keyboard
for event in device.read_loop():
    if event.type == ecodes.EV_KEY:
        print(categorize(event))

当我运行脚本并读取一个条形码487800017702297980000411000000000000702407088651000000时，我得到以下输出：

^{pr2}$

我不知道如何将密钥转换为正确的字符。如果我只过滤事件，我仍然不知道什么是密钥等。Evetest给出了以下信息：

$ evtest /dev/input/event0
Input driver version is 1.0.1
Input device ID: bus 0x3 vendor 0x5f9 product 0x2216 version 0x110
Input device name: "Datalogic ADC, Inc. Handheld Barcode Scanner"
Supported events:
  Event type 0 (EV_SYN)
  Event type 1 (EV_KEY)
    Event code 1 (KEY_ESC)
    Event code 2 (KEY_1)
    Event code 3 (KEY_2)
    Event code 4 (KEY_3)
    Event code 5 (KEY_4)
    Event code 6 (KEY_5)
    Event code 7 (KEY_6)
    Event code 8 (KEY_7)
    Event code 9 (KEY_8)
    Event code 10 (KEY_9)
    Event code 11 (KEY_0)
    Event code 12 (KEY_MINUS)
    Event code 13 (KEY_EQUAL)
    Event code 14 (KEY_BACKSPACE)
    Event code 15 (KEY_TAB)
    Event code 16 (KEY_Q)
    Event code 17 (KEY_W)
    Event code 18 (KEY_E)
    Event code 19 (KEY_R)
    Event code 20 (KEY_T)
    Event code 21 (KEY_Y)
    Event code 22 (KEY_U)
    Event code 23 (KEY_I)
    Event code 24 (KEY_O)
    Event code 25 (KEY_P)
    Event code 26 (KEY_LEFTBRACE)
    Event code 27 (KEY_RIGHTBRACE)
    Event code 28 (KEY_ENTER)
    Event code 29 (KEY_LEFTCTRL)
    Event code 30 (KEY_A)
    Event code 31 (KEY_S)
    Event code 32 (KEY_D)
    Event code 33 (KEY_F)
    Event code 34 (KEY_G)
    Event code 35 (KEY_H)
    Event code 36 (KEY_J)
    Event code 37 (KEY_K)
    Event code 38 (KEY_L)
    Event code 39 (KEY_SEMICOLON)
    Event code 40 (KEY_APOSTROPHE)
    Event code 41 (KEY_GRAVE)
    Event code 42 (KEY_LEFTSHIFT)
    Event code 43 (KEY_BACKSLASH)
    Event code 44 (KEY_Z)
    Event code 45 (KEY_X)
    Event code 46 (KEY_C)
    Event code 47 (KEY_V)
    Event code 48 (KEY_B)
    Event code 49 (KEY_N)
    Event code 50 (KEY_M)
    Event code 51 (KEY_COMMA)
    Event code 52 (KEY_DOT)
    Event code 53 (KEY_SLASH)
    Event code 54 (KEY_RIGHTSHIFT)
    Event code 55 (KEY_KPASTERISK)
    Event code 56 (KEY_LEFTALT)
    Event code 57 (KEY_SPACE)
    Event code 58 (KEY_CAPSLOCK)
    Event code 59 (KEY_F1)
    Event code 60 (KEY_F2)
    Event code 61 (KEY_F3)
    Event code 62 (KEY_F4)
    Event code 63 (KEY_F5)
    Event code 64 (KEY_F6)
    Event code 65 (KEY_F7)
    Event code 66 (KEY_F8)
    Event code 67 (KEY_F9)
    Event code 68 (KEY_F10)
    Event code 69 (KEY_NUMLOCK)
    Event code 70 (KEY_SCROLLLOCK)
    Event code 71 (KEY_KP7)
    Event code 72 (KEY_KP8)
    Event code 73 (KEY_KP9)
    Event code 74 (KEY_KPMINUS)
    Event code 75 (KEY_KP4)
    Event code 76 (KEY_KP5)
    Event code 77 (KEY_KP6)
    Event code 78 (KEY_KPPLUS)
    Event code 79 (KEY_KP1)
    Event code 80 (KEY_KP2)
    Event code 81 (KEY_KP3)
    Event code 82 (KEY_KP0)
    Event code 83 (KEY_KPDOT)
    Event code 85 (KEY_ZENKAKUHANKAKU)
    Event code 86 (KEY_102ND)
    Event code 87 (KEY_F11)
    Event code 88 (KEY_F12)
    Event code 89 (KEY_RO)
    Event code 90 (KEY_KATAKANA)
    Event code 91 (KEY_HIRAGANA)
    Event code 92 (KEY_HENKAN)
    Event code 93 (KEY_KATAKANAHIRAGANA)
    Event code 94 (KEY_MUHENKAN)
    Event code 95 (KEY_KPJPCOMMA)
    Event code 96 (KEY_KPENTER)
    Event code 97 (KEY_RIGHTCTRL)
    Event code 98 (KEY_KPSLASH)
    Event code 99 (KEY_SYSRQ)
    Event code 100 (KEY_RIGHTALT)
    Event code 102 (KEY_HOME)
    Event code 103 (KEY_UP)
    Event code 104 (KEY_PAGEUP)
    Event code 105 (KEY_LEFT)
    Event code 106 (KEY_RIGHT)
    Event code 107 (KEY_END)
    Event code 108 (KEY_DOWN)
    Event code 109 (KEY_PAGEDOWN)
    Event code 110 (KEY_INSERT)
    Event code 111 (KEY_DELETE)
    Event code 113 (KEY_MUTE)
    Event code 114 (KEY_VOLUMEDOWN)
    Event code 115 (KEY_VOLUMEUP)
    Event code 116 (KEY_POWER)
    Event code 117 (KEY_KPEQUAL)
    Event code 119 (KEY_PAUSE)
    Event code 121 (KEY_KPCOMMA)
    Event code 122 (KEY_HANGUEL)
    Event code 123 (KEY_HANJA)
    Event code 124 (KEY_YEN)
    Event code 125 (KEY_LEFTMETA)
    Event code 126 (KEY_RIGHTMETA)
    Event code 127 (KEY_COMPOSE)
    Event code 128 (KEY_STOP)
    Event code 129 (KEY_AGAIN)
    Event code 130 (KEY_PROPS)
    Event code 131 (KEY_UNDO)
    Event code 132 (KEY_FRONT)
    Event code 133 (KEY_COPY)
    Event code 134 (KEY_OPEN)
    Event code 135 (KEY_PASTE)
    Event code 136 (KEY_FIND)
    Event code 137 (KEY_CUT)
    Event code 138 (KEY_HELP)
    Event code 140 (KEY_CALC)
    Event code 142 (KEY_SLEEP)
    Event code 150 (KEY_WWW)
    Event code 152 (KEY_SCREENLOCK)
    Event code 158 (KEY_BACK)
    Event code 159 (KEY_FORWARD)
    Event code 161 (KEY_EJECTCD)
    Event code 163 (KEY_NEXTSONG)
    Event code 164 (KEY_PLAYPAUSE)
    Event code 165 (KEY_PREVIOUSSONG)
    Event code 166 (KEY_STOPCD)
    Event code 173 (KEY_REFRESH)
    Event code 176 (KEY_EDIT)
    Event code 177 (KEY_SCROLLUP)
    Event code 178 (KEY_SCROLLDOWN)
    Event code 179 (KEY_KPLEFTPAREN)
    Event code 180 (KEY_KPRIGHTPAREN)
    Event code 183 (KEY_F13)
    Event code 184 (KEY_F14)
    Event code 185 (KEY_F15)
    Event code 186 (KEY_F16)
    Event code 187 (KEY_F17)
    Event code 188 (KEY_F18)
    Event code 189 (KEY_F19)
    Event code 190 (KEY_F20)
    Event code 191 (KEY_F21)
    Event code 192 (KEY_F22)
    Event code 193 (KEY_F23)
    Event code 194 (KEY_F24)
    Event code 240 (KEY_UNKNOWN)
  Event type 4 (EV_MSC)
    Event code 4 (MSC_SCAN)
  Event type 17 (EV_LED)
    Event code 0 (LED_NUML)
    Event code 1 (LED_CAPSL)
    Event code 2 (LED_SCROLLL)
    Event code 3 (LED_COMPOSE)
    Event code 4 (LED_KANA)
  Event type 20 (EV_REP)
Properties:
Testing ... (interrupt to exit)

感谢任何帮助！谢谢您。在

Answer 1

这是一个字符设备意味着它面向字节，因此每个事件都提供1字节（unicode UTF-8）信息

要从条形码扫描仪生成的每个事件中获取unicode字母（1字节），可以使用

ev1 = ""
ev1 = event.unicode

然后将ev1, ev2,...附加到面向块的格式中。使用数组缓冲区追加单个事件字节

有关字符（字节）或面向块的信息，请参见http://en.wikipedia.org/wiki/Device_file

您还可以检查alpha unicodeevent.unicode.isalpha()

http://www.stackoverflow.com/questions/14111381/how-to-make-pygame-print-input-from-user

Answer 2

为了实现无人驾驶，USB条形码阅读器模拟HID设备（实际上是键盘）。它有一些简洁的特点：

• 开箱即用
• 它可以在任何应用程序中使用
• 它适用于任何操作系统。在

读者的默认行为只是模拟击键。他们读代码，解码，转换成文本，然后把文本转换成按键。你的电脑唯一能看到的就是USB键盘扫描代码，你的操作系统将按键转换回文本。这有一个主要的缺点：它依赖于键盘语言映射设置，因此读者必须知道要使用什么样的keymap（除了HID中的键之外，没有通用的方法来发送文本）。在

为了克服这个问题，一些条形码扫描仪可以（ab）使用Windows输入子系统的功能，用户可以直接输入ASCII码。当该功能被启用时，读取器模拟在按住左Alt键的同时键入十进制ASCII码。这样，就不会依赖于当前的键盘映射（但这会使另一个依赖于Windows输入层）。在

这里，就是这样。首先，barcode发出一个按下NumLock键，以检索Num Lock的当前状态（它将接收到Num Lock LED状态的切换）以确保启用它。然后它发出一系列Alt按下+数字按下/释放+Alt释放。如果解码它，它是：052，056，055，050，等等。52是4，56表示{}，55表示{}，50表示{}，等等

如果您更改了读卡器的配置，您可能可以禁用此功能以使用给定的keymap返回到通常的输入键。条形码的配置通常需要扫描手册中的特殊条形码。你的条形码手册应该可以在网上找到，如果你没有它。大多数情况下，配置代码在给定品牌内是可互操作的。在