Data Sheet

Compatibility with Arduino shields and accessories

The A-Star 32U4 Prime matches the Arduino Leonardo and the Arduino Uno R3 in the shape of its circuit board and

the arrangement of its pins. Furthermore, it uses the same ATmega32U4 microcontroller as the Leonardo, running at

the same voltage and frequency, so the A* should generally work with any shield or accessory that is compatible with

the Leonardo (including our Zumo Robot for Arduino [http://www.pololu.com/product/2510]).

LEDs

The A-Star 32U4 Prime has five indicator LEDs.

A blue power LED located next to the power switch indicates when the onboard regulator is active (an external power

supply is connected and the switch is turned on).

A green power LED next to the USB connector indicates when the USB bus voltage (VBUS) is present.

A yellow user LED is connected to Arduino pin 13, or PC7. You can drive this pin high in a user program to turn this

LED on. The A-Star 32U4 Bootloader [http://www.pololu.com/docs/0J61/9] fades this LED on and off while it is waiting

for a sketch to be loaded.

A green user LED is connected to PD5 and lights when the pin is driven low. While the board is running the A-Star

32U4 Bootloader or a program compiled in the Arduino environment, it will flash this LED when it is transmitting

data via the USB connection.

A red user LED is connected to Arduino pin 17, or PB0, and lights when the pin is driven low. While the board is

running the A-Star 32U4 Bootloader or a program compiled in the Arduino environment, it will flash this LED when

it is receiving data via the USB connection.

The AStar32U4Prime library contains functions that make it easier to control the three user LEDs. All three user LED

control lines are also LCD data lines, so you will see them flicker when you update the LCD. The green and red user

LEDs also share I/O lines with pushbuttons (see below).

5. A-Star 32U4 Prime Page 21 of 47