We decided to read the ATtiny212/412 microcontroller data sheet. We've had experience reading MC datasheets before. They can be very tedious but they are true lifesavers when debugging and designing circuits. By far, the most useful page when it comes to a quick setup is the page that has the pinout diagram for the MC. This pages allows you to see, at a high level, what each pin is for. When looking to set up a board with simple functionalities this is the page to visit!
Most of our board designs make use of the internal pullup resistor that the MC's pins have. You can find diagrams of for each port's internal connection on the data sheet as well. This knowledge can help you simplify your external designs component wise.
A neat function of this MC is that you can use external clock to run it. This allows for flexibility when designing more complex systems. Thankully, we can find information about connecting external clocks to the MC.
Sleep Mode! Sleep mode is a function that allows for great saves in energy. Many of the applications that I'm thinking to give my circuits could benefit greatly from this fucntion. The date sheet is a bit hard to understand but it gives good pointers towards what one should be thinking about for being able to enable sleep mode on the tiny!