Using the STC11F02 microcontroller, the HT1380 RTC chip, made a simple clock, showing the time of the year, month and day, with adjustment function. It has been used normally for about two years. The clock and data lines of the RTC chip are connected to the P3.0 and P3.1 (serial port) of the MCU. In the past few days, I tried to change the clock and data lines of the RTC chip to the other two idle I/O ports. As a result, the trouble caused the clock to start running and the minute will change. The number of hours has changed for a while, and the year, month, day, and week are also chaotic. When the date is adjusted, the time becomes all zero. I don't know if the MCU is broken or the RTC chip is broken. It seems that I have changed a new HT1380. I am waiting for the expert to give an answer.