Overview
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.
Note: Batteries can have much higher voltages than their nominal voltages when fully charged, so be careful with nominal voltages above 24 V. A 36 V battery is not appropriate for this product.
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
Dimensions
| Size: |
0.7" × 1.95" × 0.23"1
|
| Weight: |
3.4 g2
|
General specifications
| Processor: |
ATmega32U4 @ 16 MHz |
| RAM size: |
2560 bytes |
| Program memory size: |
32 Kbytes3
|
| Motor channels: |
0 |
| User I/O lines: |
26 |
| Input voltage range: |
5 V to 40 V (SV) |
| Minimum operating voltage: |
5 V4
|
| Maximum operating voltage: |
40 V |
| Maximum output current: |
800 mA5
|
| Logic voltage: |
5 V |
| Reverse voltage protection: |
Y6
|
| External programmer required: |
N |
Notes:
- 1: Without included optional headers. This measurement includes the USB Micro-B connector, which extends 0.05" past the edge of the PCB.
- 2:Without included optional headers.
- 3: Note that 4 KB of the MCU's 32 KB of flash memory is used by the pre-installed USB bootloader. All 32 KB is available when programming via the ISP header rather than the bootloader.
- 4: For light loads. The regulator's dropout voltage increases approximately linearly with the load, from a few millivolts at no load up to around 0.6 V at 500 mA.
- 5: Available current depends on input voltage, current consumed by the board, ambient conditions, and regulator topology. See product documentation and performance graphs for details.
- 6: On Bat+ (LV, SV) or Bat- (ULV).
Package List
1x Pololu A-Star 32U4 Mini SV
2x 1×17-pin breakaway 0.1" male headers
1x 2×3 header
