The A-Star 32U4 Mini ULV is a programmable module based on the ATmega32U4 from Atmel. Unlike competing products, it has an onboard switching step-up regulator that allows it to be powered efficiently from a 0.5 V to 5.5 V supply. This compact 1.9″ × 0.7″ board breaks out all 26 of the microcontroller’s I/O pins (of which 7 can be used as PWM outputs and 12 as analogue inputs), and loading programs is made easier by a Micro-USB interface and a preloaded Arduino-compatible bootloader.
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-Star 32U4 Mini; 7 of these are usable as PWM outputs and 12 are usable as analogue 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-Star easy to use with solderless breadboards, perfboards, and 0.1″-pitch connectors.