Arduino A000008 Yun ATmega32u4 Microcontroller Board

The Arduino Yun is a microcontroller board based on the ATmega32u4 (datasheet) and the Atheros AR9331. The Atheros processor supports a Linux distribution based on OpenWRT named Linino. The board has built-in Ethernet and Wi-Fi support, a USB-A port, micro-SD card slot, 20 digital input/output pins (of which 7 can be used as PWM outputs and 12 as analog inputs), a 16 MHz crystal oscillator, a micro USB connection, an ICSP header and a 3 reset buttons. The Yun distinguishes itself from other Arduino boards in that it can communicate with the Linux distribution onboard, offering a powerful networked computer with the ease of Arduino. In addition to Linux commands like cURL, you can write your own shell and python scripts for robust interactions. The Yun is similar to the Leonardo in that the ATmega32u4 has built-in USB communication, eliminating the need for a secondary processor. This allows the Yun to appear to a connected computer as a mouse and keyboard, in addition to a virtual (CDC) serial / COM port. The Bridge library facilitates communication between the two processors, giving Arduino sketches the ability to run shell scripts, communicate with network interfaces and receive information from the AR9331 processor. The USB host, network interfaces and SD card are not connected to the 32U4, but the AR9331 and the Bridge library also enables the Arduino to interface with those peripherals Wi-Fi is built in, but there is no external Wi-Fi antenna included.