说明：  PIC单片机产生警报声的程序。频率从1.8K-3.5K匀速增加，共有46个频点，每个频点扫频16个半周期，持续200mS。
(PIC Singlechip alarms generated procedures. Frequencies from the uniform increase of 1.8K-3.5K, a total of 46 frequencies, each frequency sweep 16 semi-cycle, continuous 200mS.)