AT89C51利用PCF8574演示I2C的通信,并用了7SEG-MPX4-CC数码管的Keil uVision4 C语言代码，并用proteus演示成功。(AT89C51 uses PCF8574 to demonstrate the communication of I2C, and uses Keil uVision4 C language code of 7SEG-MPX4-CC digital tube, and demonstrates success with proteus.)