如何使用 Python 获取原始 USB 键盘数据？

Question

我在 Python 中使用 PyUSB，因为我必须监听 USB 端口才能从电子卡中检索数据。目前，我必须通过从连接到 Raspberry-Pi 的小键盘（USB 连接）读取直接输入来训练自己。当然，我不想阅读类型化的字符串，我希望得到例如 ASCII 码。我只是不明白如何从我的 USB 键盘读取输入。

我已经找到了一些 sn-ps：

import usb.core
import usb.util

VENDOR_ID = 0x0922
PRODUCT_ID = 0x8003

# find the USB device
device = usb.core.find(idVendor=VENDOR_ID,
                       idProduct=PRODUCT_ID)

# use the first/default configuration
device.set_configuration()
# first endpoint
endpoint = device[0][(0,0)][0]

# read a data packet
attempts = 10
data = None
while data is None and attempts > 0:
    try:
        data = device.read(endpoint.bEndpointAddress,
                           endpoint.wMaxPacketSize)
    except usb.core.USBError as e:
        data = None
        if e.args == ('Operation timed out',):
            attempts -= 1
            continue

print data

如果我取消注释导致“设备正忙”异常的以下行“device.set_configuration()”，我要么收到错误 16“设备正忙”，要么什么都没有...（我确实替换了 VENDOR_ID 和 PRODUCT_ID用我的键盘ID）

Answer 1

我假设您使用的是 Linux，正如您提到的 Raspberry Pi。您可以使用python-evdev 从/dev/input/ 中的事件设备中读取数据。

例如：

from evdev import InputDevice, categorize, ecodes

device = InputDevice("/dev/input/event3") # my keyboard
for event in device.read_loop():
    if event.type == ecodes.EV_KEY:
        print(categorize(event))

输出：

key event at 1462881252.506405, 30 (KEY_A), up
key event at 1462881252.541371, 31 (KEY_S), up
key event at 1462881252.616399, 31 (KEY_S), down
key event at 1462881252.674422, 22 (KEY_U), down
key event at 1462881252.730418, 31 (KEY_S), up
key event at 1462881252.745558, 22 (KEY_U), up
key event at 1462881252.808419, 50 (KEY_M), down
key event at 1462881252.914552, 23 (KEY_I), down
key event at 1462881252.925388, 50 (KEY_M), up
key event at 1462881253.003579, 49 (KEY_N), down
key event at 1462881253.066418, 34 (KEY_G), down