I'm working on a project called The Fifty Year Beep. The goal is to produce a battery-powered circuit that will beep once and only once fifty years from now. It is an art project of a kind, inspired to some degree by the 10000 year clock. I love the idea of me and my friends gathering together as old men to listen to a single derpy beep.
Ideally, the clock is self contained and powered. Our current thinking is that lithium cell batteries are our best bet, given that there are examples of computers from the 90s where the button cells are still good.
We started looking at off the shelf RTC module like the DS3231. The datasheet lists a timekeeping current of ~1uA at ~3V. A CR2477 coin cell has ~1000mAH at ~3V. Naively, this gives a lifetime of about 100 years. Naively.
My main question is about the choice of RTC module. The DS3231 has an alarm feature that seemed promising at first. However, as far as I can tell, the alarm can’t be set more than one month in the future.
We don’t have experience selecting or searching for microchips. Is there a single chip that can do this job? Or should we be building a system that combines an RTC chip with a low power microcontroller?
Any suggestions or advice would be appreciated!