Time.h library for making a digital watch

Hi everyone.

I'm using Arduino UNO with a 74HC595 chip and a 4-digit 7 segment display. I've downloaded the library Time.h in order to create a software clock, for then displaying the hour at the display.

The problem is that the internal clock has not a good precission. I left it from 5 hours and the clock losed a half minute of synchronization. How can I improve the accuracy?

Thank you. My best regards,

Bivalvo.

How can I improve the accuracy?

Of the Arduino? Remove the oscillator, and replace it with a crystal regulator. Not that easy, considering the tiny size of the parts involved.

Well, at the moment I'm using Arduino UNO for the prototypes, but my objective is to design the watch using ATMega 328P on a PCB.

So, when you design your PCB design it using a decent crystal, not an oscillator.

But on an implementation it also will be neccesary to use crystal + capacitors.