DFRobot Beetle smallest Arduino

Beetle is an extremely small Arduino Leonardo board. The Beetle board from DFRobot comes with an Atmel AtMega32u4 running at 16MHz. To program the board, simply connect a micro USB cable to the board and your PC, and upload programs to the microcontroller using the Arduino software. When programming with the Arduino software, you need to select the "Arduino Leonardo" board (Tools > Board > Arduino Leonardo). The built-in ATmega32U4 comes with a bootloader that allows you to upload any code applicable to Arduino Leonardo.

Features:
Compact size of only 20 mm x 22 mm
Direct downloading of programs and testing via micro USB
Large gold-plated IO ports allow for direct wire attachment; for example, it can be sewn onto clothing with conductive thread.

Technical Details:
Microcontroller: ATmega32u4
Clock Frequency: 16 MHz
Operating Voltage: 5V DC
Digital I/O Pins: 10
PWM Channels: 4
Analog Input Channels: 5
UART: 1
I2C: 1
Micro USB: 1
Power Connections: 2
Flash Memory: 32 KB, of which 4 KB is used by the bootloader
SRAM: 2.5 KB
EEPROM: 1 KB
Dimensions: 20 x 22 x 3.8 mm
Weight: 7.3 g

Included in the package:
1x Beetle.