实际上，当单片机启动或复位时，所有的I/O插脚缺省为输入。也就是说，如

实际上，当单片机启动或复位时，所有的I/O插脚缺省为输入。也就是说，如果将胡须连接到单片机某个I/O管脚时，该管脚会自动作为输入。作为输入，如果I/O脚上的电压为5V，则其相对应的I/O口寄存器中的相应位存储1；如果电压为0V，则存储0。
布置恰当的电路，可以让胡须达到上述效果：当胡须没有被碰到时，使I/O脚上的电压为5V；当胡须被碰到时，则使I/O脚上电压为0。然后，单片机就可以读入相应数据，进行分析、处理，控制小车的运动。
当没有触碰到物体时，I/O引脚P1.4或P1.7上电压为5V。
当触碰到物体时，I/O引脚P1.4或P1.7上电压为0V。

結果 (中文) 3:

In fact, when the microcontroller start or reset, the default for all input pins I/O. That is, if the beard is connected to the microcontroller I/O pin, the pin will automatically as the input. As input, if the voltage on the I/O pin is 5V, the corresponding bits in the corresponding I/O register are stored 1; if the voltage is 0V, the storage is 0. The proper circuit can be achieved by a beard to achieve the effect: when the beard is not met, the voltage on the I/O pin is 5V; when the beard is touched, the I/O pin is 0. Then, the microcontroller can read the corresponding data, analysis, processing,Control the movement of the car. I/O pin P1.4 or P1.7 on the is 5V. I/O pin P1.4 or P1.7 on the is 0V, when the touch of an object is touched.