Beetle CM-32U4 Micro Leonardo Compatible Controller, ATmega32U4 - 

DFR0816 is an 8-bit embedded evaluation board. It's compatible with Arduino Leonardo and is an enhanced version of the Beetle module. Beetle CM-32U4 is a micro Leonardo controller with an onboard charging chip. As an upgraded version of the DFRobot Beetle Board, this board is greatly optimized in integration and usability, which makes it well applicable to Arduino projects that require compact size and long service life. Just like the Beetle series, despite a mini body, it has powerful functionalities. On a size of only 22mm x 20.5mm, Beetle CM-32U includes most commonly-used communication interfaces: 1×I2C, 1×SPI, 1×UART, 2×analog Interface, 2×digital interface, 2×GND reserved and 1×5V output, which are all designed as pin connector form, more intuitive and easy to use compared with the onboard pads of Beetle. Besides, Beetle CM-32U4 supports official Leonardo firmware, which means you can directly use it in Arduino IDE without extra download.