说明：  LPC23xx系列ARM关于GPIO的操作，包括方向设置、输出高/地电平、输入，GPIO用作中断的触发方式等等。PPT非常出色，简单明了。
(LPC23xx series of ARM on the GPIO operation, including setting the direction, the output of high/land-level, input, GPIO trigger for the disruption and so on. PPT very good, simple and clear.)