Arduino is an interesting platform to experiment with. But using standard Arduino board is not always a best solution. For small projects like controlling LEDs or relays smaller MCU boards would be better choice. This is why Digispark came up with a new shape of Arduino board. Making tiny board they’ve chosen smaller microcontroller as well. As we already know Attiny85 runs well Arduino code it is ideal solution in six legged package.
The board is designed to serve as USB connector which solves power and serial interface problems. Arduino board has 6 pins where two of them are already used for USB. But they can be used as general purpose I/O. Overall there is I2C and SPI available, 3PWM four analog inputs, power LED and status LED. The board size is 17.5mm by 19mm. This is an open hardware project that awaits your feedback on improvements and shield requests.