That was more intense and exciting than I anticipated! I thought building my first “homebrew Arduino” from an atmega 328p and controlling an OLED via I2C shouldn’t be too complicated.
In fact, it isn’t, but there are a couple of things you have to think of, especially when you do it in this contrained space.
Yeah, so finally, here’s the first power up! The date / time is wrong because the third perf board with the RTC and the speaker are not connected yet, so the clock starts when the atmega is powering up: