说明：  单片机M16+LCD数字频率计，/* 目标MCU:MEGA16 晶振:外部8MHZ */ /*基于LCD的频率计，PC0~PC2对E,RS,RW PORTA接DATA的8根线 用PB0口产生5000HZ方波，并二的N次分频 给ICP1输入补捕捉，既练习TC中断又有ICP
(SCM M16+ LCD digital frequency meter, /* Target MCU: MEGA16 Crystal: External 8MHZ*//* frequency count based on LCD, PC0 ~ PC2 on the E, RS, RW PORTA then the eight lines with DATA ports PB0 have 5000HZ square wave, and two of N times the input frequency to the ICP1 make capture, not only interrupt another ICP exercises TC)