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树莓派的小键盘（USB连接）读取直接输入来训练自己。当然，我不想读取类型化的字符串，例如，我希望获得ASCII代码。我只是不知道如何从USB键盘上读取输入。

我已经找到了一些片段：

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"Device is busy"异常的以下行"Device.set_config（）"，我要么得到错误16"Device is busy"，要么什么都没有。。。（我确实用键盘的ID替换了VENDOR_ID和PRODUCT_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