in our protection device, can is used for the communication of double mcu, one is the main protection mcu, which gathers the analog data, drives the switch-out and switch-in circuit, the other is managing mcu, which takes charge the person-computer dialogue and the communication with the outside devices 本文采取硬件时钟方式为数字保护装置提供时钟显示,利用iic与时钟芯片pcf8583的通信,直接取得对pcf8583进行时钟校正和获取时钟,并对软件时钟进行修改。