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.

A-Star 32U4 Mini ULV, LV, and SV.

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.

Our comprehensive user’s guide provides the basics you need to get started with the A-Star as well as detailed technical information for advanced users.

This product requires a USB A to Micro-B cable (not included) to connect to a computer.

Features

• 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)
  • 2.5 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

The A-Star family

 

From top to bottom: A-Star 328PB Micro, 32U4 Micro, 32U4 Mini SV, and 32U4 Prime SV.

 

The A-Star 32U4 Micro is a part of our larger A-Star family, all of whose members are based on AVR microcontrollers and are preloaded with Arduino-compatible bootloaders. The table below shows some key features and specifications of our A-Star microcontroller boards to help you choose the right one for your application.

	A-Star 328PB Micro	A-Star 32U4 Micro	A-Star 32U4 Mini ULV A-Star 32U4 Mini LV A-Star 32U4 Mini SV	A-Star 32U4 Prime LV A-Star 32U4 Prime SV	A-Star 32U4 Robot Controller LV A-Star 32U4 Robot Controller SV
Microcontroller:	ATmega328PB	ATmega32U4
User I/O lines:	24	18	26	26(1)	26(1)
PWM outputs:	9	7	7	7	7(1)
Analog inputs:	8	8	12	12	12(1)
Ground access points:	6	2	4	43	44
User LEDs:	1	2	3	3	3
User pushbuttons:	—	—	—	3	3
USB interface:
Reset button:
Power switch:
Buzzer option:
microSD option:
LCD option:
Motor drivers:
Operating voltage:	3.3V VCC:3.8 V to 15 V 5V VCC:5.5 V to 15 V	5.5 V to 15 V	ULV: 0.5 V to 5.5 V LV: 2.7 V to 11.8 V SV: 5 V to 40 V	LV: 2.7 V to 11.8 V SV: 5 V to 36 V	LV: 2.7 V to 11 V SV: 5.5 V to 36 V
Regulator type:	3.3 V or 5 V linear	5 V linear	5 V switching ULV: step-up LV: step-up/step-down SV: step-down	5 V switching LV: step-up/step-down SV: step-down	5 V switching LV: step-up/step-down SV: step-down
Regulated current:(2)	100 mA	100 mA	ULV:500 mA LV: 1 A SV:800 mA	1 A	LV: 1 A SV: 1.5 A
Dimensions:	1.3″ × 0.7″	1″ × 0.6″	1.9″ × 0.7″	2.8″ × 2.1″	2.6″ × 2.2″

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