Here is some information about how to use ATtiny85 with Arduino IDE. ATtiny85 is a small (only 8-pin MCU from Atmel) and is available in both DIP8 (Hole Mount) or SOIC8 (Surface Mount) . These are available in a lot of finished products such as Adafruit Gemma , Adafruit Trinket and LilyPad . There are many other cards on the market, but let's start from the beginning. ATtiny85 has 8Kbytes Flash (program memory), 512bytes EEPROM, 512bytes RAM and only 8 sticks, the entire data sheet can be loaded here . 2 pins are needed for feeding, only 6 I / O left (PB0-PB5), but you often want one of the I / O pins as external RESET (PB5) to remain 5 I / O green 0-4 in the picture below). Why do you want to use such a small rack? In some cases, this may be enough if you have an easy task to perform, space shortage, energy-saving or cost-critical application. You drive with an internal osci...