本程序用按键计数测试24C02随机读写程序，每次从0位开始读数据，读到标记位后返回变量，下次写入又从标记位写入，相当于写入一个8位数据在24C02的2个地址分别写入了一次，但可以充分利用24C02的256个地址（0-255），对24C02寿命有一定延长作用。24C02使用过一次之后可以删除初始化函数中的write_at24c02(255,0)语句。(Button count test 24C02 random read and write procedures for the program, read the data from the beginning of each 0 bit, read bit return variables, and from the next write bit is written, the equivalent of writing a 8 bit data in 2. 24C02 were written once, but you can make full use of 24C02 address 256 the (0-255), has a certain effect on prolonging the lifetime of 24C02. After once used, 24C02 can delete the write_at24c02 (255,0) statement in the initialization function.)