This Arduino compatible board is equipped with ATmega32U4 that operates at 3.3V/8MHz. Equipped with 9 x 10-bit A/D converters, 5 x PWM pins, 12 x DIOs, and Rx/Tx for serial connections. Similar to the Pro Mini except the ATmega32U4. Note: Since it is equipped with a voltage regulator, you can add a maximum of 12 V voltage, but if you are supplying unadjusted power, please connect it to the RAW pin instead of VCC. It operates at 3.3 V, so regular 3.3 V sensors are easy to use, but please note that the system voltage limitations. Specifications: ATMega32U4 operating at 3.3V/8MHz, support Arduino IDE v1.0.1, equipped with a microUSB connector for programming, 10-bit A/D converter x 9, digital I/O x 12 (5 pieces are PWM compatible), serial connection by Rx/Tx, Size: 33 x 17.8 mm (Materials) Schematicup Eagle FilesHook. Guide, Graphical Datasheet, Datasheet (ATMega 32U4), Firmware Note, Arduino Addon Files, Arduino Addon Files (IDE 1.5+), GitHub (Design Files)