1. Write the changed time value back to the clock register of ds1302, and pay attention to disable write protection before writing. When I was writing this, I ignored this point and could not write it all the time, almost crashed.
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2. Also pay attention to the time is 24\/12 mode, if your perpetual calendar can set the time display mode, pay attention to the difference between the 24 mode and the 12 mode write time register