Recently Great Scott built his DIY version of a tachometer which I thought was very cool (https://youtu.be/6QZMt4yyylU). But using an ATmega for this task, I found a bit overpowered. So I tried to force all tasks (measurement, calculation, I²C protocol and OLED display) into the huge 1KByte memory of an ATtiny13.Description and project files: https://github.com/wagiminator/ATtiny13-TinyTacho