用普通I/O口模拟I2C通信读写vs1307时钟芯片程序，此程序在MPLAB IDE环境下开发，在PIC16F877单片机上运行通过。-With common I/O port to read and write clock chip vs1307

CH452的真正2线接口，含低电平脉冲按键中断在内，只需要2个I/O引脚，兼容I2C/IIC时序,两线制方式SCL/SDA，按键中断由SDA产生，接单片机的脉冲/边沿中断引脚.-CH452 true two-wire interface, with low pulse button interrupt included, requires only two I/O pins, compatible I2C/IIC timing, two-wire mode SCL/SDA, SDA genera