AVR单片机定时器2的异步操作功能用作实时时钟的效果。同时讲解了BASCOM-AVR中关于时钟硬件配置方面的语句。在BASCOM的概念里主要分为SOFT和USER两大类时钟产生的方法。利用芯片定时器的异步功能称为软时钟，利用专用时钟芯片则要用户自己编写相应的处理程序，所以称USER。但不管采用哪种方式，相关的中断服务程序或是函数都要支持DATE$和TIME$以及_sec , _min , _hour, _day , _month , _year等系统内部变量。程序的其他部分可以直接存取这些变量，使得时间操作变得规范化，大大方便了程序设计-AVR microcontroller Timer 2 functions as a real-time clock asynchronous operation results. Also explained the BASCOM-AVR clock hardware configuration on the statement. Concept of years in BASCOM divided into two categories USER SOFT and clock generation method. Use of chip asynchronous timer feature called soft clock, using dedicated clock chip will have to write the corresponding user' s own procedures, so that USER. But Either way, the relevant interrupt service routine, or function must support DATE $ and TIME $ and _sec, _min, _hour, _day, _month, _year other variables within the system. Other parts of the program can directly access these variables, making time operation has become standardized, greatly facilitates programming