digital sensor 数字传感

discrete signal 离散信号

Pull-down Resistor 下拉电阻

serial.begin 波特率

indicate 表明

oscilloscope 示波器 threshold临界点

关于代码中有Map 的部分，需要调整数值，电阻

PWM (Pulse Width Modulation)

Uses a fixed-frequency square wave signal (on/off signal) to simulate varying voltage levels.

The key to control is the proportion of time the high voltage level is maintained, the duty cycle.

Common Uses of PWM

Controlling Motor Speed: Adjusting the Average Motor Voltage and Speed by Changing the Duty Cycle

Adjusting LED Brightness: Rapid Brightness Changes, Fast Voltage Pulse Switching

Blessing Click Control: Multi-level control uses the PWM pulse width to determine the angle.

Using the Arduino UNO as an example, the "wavy line" represents the analog output.

PWM Pulse Width Modulation 脉宽调制

用固定频率的方波信号（开关信号）来模拟出不同的电压大小