“In this post, I go over how to generate a 1Hz clock source through an unusual way.
I have been looking for an accurate clock source for another project (that I will be publishing here soon). The more accurate an oscillator or crystal is, the more expensive it becomes. The easiest way to generate a 1Hz clock source is to generate or use a 32.768 kHz source. It’s a common frequency available and it cleanly divides down to 1Hz.
During my search for accurate 32.768 kHz TCXOs, I found one from Maxim IC. It was their popular DS32xx family of RTC ICs and they specifically made a TCXO version only. From there, I found these two parts: DS3231 and DS3232M. They are RTC chips but also have a dedicated 32.768 kHz output. Two main differences between them is that the DS3231M runs off +2.3 to +5.5 volts and requires a pullup on the 32.768 kHz output.
Now, obviously, using a dedicated a 32.768 kHz TCXO would be the best way to go, but where is the fun in that? I wanted to see if I could use this RTC chip as a standalone 1Hz source (spoiler alert: you can, but with some caveats).”