在Linux下，可以使用Python直接读取dev/input目录下键盘和鼠标等设备文件，获取数据。
使用Python读取设备数据
例如读取键盘/dev/input/event3:
import struct
with open("/dev/input/event3", "rb") as f:
while True:
data = f.read(24)
time_sec, time_usec, type_, code, value = struct.unpack("QQHHi", data)
if type_ == 0:
continue
print("{}.{}\ttype={}\tcode={}\tvalue={}".format(time_sec, time_usec, type_, code, value))
使用root权限运行程序：
$ sudo python3 demo.py
1591000780.523814 type=4 code=4 value=589825
1591000780.523814 type=1 code=272 value=1
1591000780.691889 type=4 code=4 value=589825
1591000780.691889 type=1 code=272 value=0
1591000781.787812 type=2 code=0 value=1
1591000781.787812 type=2 code=1 value=-1
1591000781.803706 type=2 code=0 value=2
1591000781.843783 type=2 code=0 value=2
1591000781.883777 type=2 code=0 value=2
每一包数据由24个字节组成，其中timeval16字节，type2字节，code2字节，value四字节。C语言结构体如下：
// struct_timeval.h
struct timeval
{
__time_t tv_sec; /* Seconds. */
__suseconds_t tv_usec; /* Microseconds. */
};
// input.h
struct input_event {
struct timeval time;
__u16 type;
__u16 code;
__s32 value;
};
结构体中type具体内容介绍见https://www.kernel.org/doc/html/v4.17/input/event-codes.html，code内容见头文件input-event-codes.h。
使用evtest查看输入设备数据
另外，如果只是想查看各输入设备的数据，可以使用evtest:
sudo apt install evtest
使用时直接以root权限运行evtest，输入对应编号即可，例如获取编码器数据：
# evtest
No device specified, trying to scan all of /dev/input/event*
Available devices:
/dev/input/event0: InputEmulator
/dev/input/event1: rotary-keys
/dev/input/event2: gpio-keys
Select the device event number [0-2]: 1
Input driver version is 1.0.1
Input device ID: bus 0x19 vendor 0x0 product 0x0 version 0x0
Input device name: "rotary-keys"
Supported events:
Event type 0 (EV_SYN)
Event type 2 (EV_REL)
Event code 0 (REL_X)
Properties:
Testing ... (interrupt to exit)
Event: time 1550141461.594735, type 2 (EV_REL), code 0 (REL_X), value -1
Event: time 1550141461.594735, -------------- SYN_REPORT ------------
Event: time 1550141461.825035, type 2 (EV_REL), code 0 (REL_X), value -1
Event: time 1550141461.825035, -------------- SYN_REPORT ------------
Event: time 1550141462.052871, type 2 (EV_REL), code 0 (REL_X), value -1
Event: time 1550141462.052871, -------------- SYN_REPORT ------------
Event: time 1550141462.199711, type 2 (EV_REL), code 0 (REL_X), value 1
Event: time 1550141462.199711, -------------- SYN_REPORT ------------
Event: time 1550141462.570028, type 2 (EV_REL), code 0 (REL_X), value 1
Event: time 1550141462.570028, -------------- SYN_REPORT ------------
Event: time 1550141464.492574, type 2 (EV_REL), code 0 (REL_X), value 1
Event: time 1550141464.492574, -------------- SYN_REPORT ------------
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原文链接：https://www.jianshu.com/p/4b207260c62e
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