I need a bit help because I’m not sure I made everything as I should. And I’m not sure it will even work or not as it is. So the idea is to make a small authenticator (login code generator) for webpages. I already made a prototype with arduino but it’s too big even with a nano so I decided to make my own. What you need for these are an RTC with the server time and a unique device id (and a bunch of code). To make it more power efficient I want to run the Atmega328p at 8Mhz, use a switch to only turn it on when the button pushed and use a CR2032 3V coin cell to power it. I use Atmega328p because the code part is really big and I wanted to make sure everything will be fine and there will be no memory overflow. The OLED display can be powered from 3V so it must work. This is my first PCB design and my first standalone Atmega, so maybe there will be problems. Thank you for your help, and if it work out then I share the whole project.
ER-OLED0.84-1_Series_Datasheet.pdf (792 KB)
DS1307.pdf (348 KB)