利用霍尔传感器测量参加竞赛的小车的行驶速度。定时器1用于定时，定时器0用于计数，并将测量到是数据通过串口上传给计算机。-Make use of the Hall sensor to measure handcart running speed engaging in a contest. Timer 1 is used for timing, timer 0 is used for counting , is pass measurement on to and a computer to being that the data passes on string. through the serial port.