根据PWM说明，可以通过Linux文件驱动MG90S电机。但是参考了2代的python代码，第一次运行后，无法第二次运行，似乎会被占用，请问这是为什么？
错误代码：
root@WalnutPi:/home/pi/Documents# python PWM.py
OSError: [Errno 16] Device or resource busy
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File “/home/pi/Documents/PWM.py”, line 47, in
pwm_export(0, 1) # \u5bfc\u51faPWM\u901a\u9053
^^^^^^^^^^^^^^^^
File “/home/pi/Documents/PWM.py”, line 20, in pwm_export
write_to_file(f"{control_path[control]}/export", str(channel))
File “/home/pi/Documents/PWM.py”, line 12, in write_to_file
with open(path, “w”) as f:
OSError: [Errno 16] Device or resource busy
感谢，如果需要更多信息，麻烦告知。