The Pololu A-Star 32U4 Mini boards are general-purpose programmable modules based on the ATmega32U4 AVR microcontroller from Microchip (formerly Atmel), which has 32 KB of flash program memory, 2.5 KB of RAM, and built-in USB functionality. The A-Star (abbreviated A*) adds a number of onboard features to support the microcontroller and make it easier to work with, including a 16 MHz crystal, a USB Micro-B connector, an in-system programming (ISP) header, a reset button, and three indicator LEDs.
Each A-Star 32U4 Mini contains a switching regulator that efficiently produces 5 V from an external voltage source to power the microcontroller. Three different versions are available, covering a wide range of input voltages:
- A-Star 32U4 Mini ULV: 0.5 V to 5.5 V
- A-Star 32U4 Mini LV: 2.7 V to 11.8 V
- A-Star 32U4 Mini SV: 5 V to 40 V
A robust power selection circuit enables seamless transitions between regulator power and USB power, and overcurrent and reverse-voltage protection help safeguard the board against accidental damage.
All 26 general-purpose I/O lines on the ATmega32U4 are accessible on the A* 32U4 Mini; 7 of these are usable as PWM outputs and 12 are usable as analog inputs. The board measures 1.9″ × 0.7″, the same size as an Arduino Micro, and features a pair of mounting holes sized for #2 or M2 screws (not included). Its 0.1″ pin spacing makes the A* easy to use with solderless breadboards, perfboards, and 0.1″-pitch connectors.
This product requires a USB A to Micro-B cable (not included) to connect to a computer.
- Dimensions: 1.9″ × 0.7″ (1.95″ × 0.7″ including USB Micro-B connector)
- Programmable 16 MHz ATmega32U4 AVR microcontroller
- 32 KB flash (4 KB used by bootloader, leaving 28 KB available for user program by default)
- 5 KB SRAM
- 1 KB EEPROM
- Native full-speed USB (12 Mbps)
- Preloaded with Arduino-compatible bootloader (no external programmer required)
- All I/O lines from the ATmega32U4 broken out in a compact package
- 26 general-purpose I/O pins available along the sides of the board
- 7 pins can be configured as hardware PWM outputs
- 12 pins can be configured as analog inputs
- 3 user-controllable LEDs
- Reset button
- Can be powered from USB or from an external source:
- ULV: 0.5 V to 5.5 V
- LV: 2.7 V to 11.8 V
- SV: 5 V to 40 V
- Switching regulator enables efficient operation
- Power selection circuit allows for seamless switching between power sources and provides overcurrent protection
- Reverse-voltage protection on external power inputs
- Precision 16 MHz crystal
- 6-pin ISP header for use with an external programmer
- Comprehensive user’s guide