The main goal of this circuit is to save energy. So, I am not going to talk about arduino because the board itself has unnecessary power overhead for a final product. It is great for development. But, not very good for final projects running on batteries. I will use one for my POC but, to save energy, using the Atmega328 standalone will give you better results

I made a weather station(TOBE) that will charge a pair of 3.7 V battery in parallel using a solar panel. My first version went very well thank you. But, I had a problem. The battery usage was greater than the charging rate of the solar panel. I am not going into numbers here. But, after a while, I noticed the battery levels were slowly going down. Aside from the fact that I am from Canada and sun here is not a commodity. I then, used a libraryto put the Atmega328 to sleep for 8 seconds(there are other timeframes but 8 secs is the higher) and then, come back to work. The usage is very straight forward and it works like it supposed. But, 8 secs was not enough for me.

EXPANDED TECHNICAL DETAILS

Hybrid Timing Architecture

This technical project explores the combination of classic analog timing with modern digital interrupts to create a ultra-stable hardware clock.

• Precision 555 Pulse Train: Uses a NE555 Timer IC configured in astable mode to generate a precise 1Hz or 10Hz square wave. This signal is fed directly into the INT0 (Pin 2) of the ATmega328P.
• Hardware Interrupt Dispatch: Instead of using internal software timers (which can drift), the Arduino treats every 555-pulse as a "Master Clock" trigger. The firmware executes critical tasks (like data logging or pulse counting) inside the ISR(INT0_vect) routine.

Performance

• Zero-Drift Execution: Ensures that the Arduino's high-level logic is perfectly synchronized with the external analog hardware, ideal for precise temporal experiments or legacy equipment interfaces.