树莓派4b使用pca9685时报错

问题遇到的现象和发生背景

用树莓派4b搭载pca9685模块控制舵机
运行实例程序时报错

Traceback (most recent call last):
  File "/home/pi/Desktop/python files/654-Servo+Motor+Test.py", line 17, in 
    pwm = Adafruit_PCA9685.PCA9685()
  File "/usr/local/lib/python3.7/dist-packages/Adafruit_PCA9685/PCA9685.py", line 75, in __init__
    self.set_all_pwm(0, 0)
  File "/usr/local/lib/python3.7/dist-packages/Adafruit_PCA9685/PCA9685.py", line 111, in set_all_pwm
    self._device.write8(ALL_LED_ON_L, on & 0xFF)
  File "/usr/local/lib/python3.7/dist-packages/Adafruit_GPIO/I2C.py", line 114, in write8
    self._bus.write_byte_data(self._address, register, value)
  File "/usr/local/lib/python3.7/dist-packages/Adafruit_PureIO/smbus.py", line 327, in write_byte_data
    self._device.write(data)
TimeoutError: [Errno 110] Connection timed out

这个是报错，随后舵机一点反应都没有
求解答，为什么会连接超时呢

注:我用的代码是现成的，实例，应该没问题