The Arduino Yún is a microcontroller board based on the ATmega32u4 and the Atheros AR9331. The Atheros processor supports a Linux distribution based on OpenWrt named Linino OS. The board has built-in Ethernet and WiFi support, a USB-A port, micro-SD card slot, 20 digital input/output pins (7 of them can be used as PWM outputs and 12 as analog inputs), a 16 MHz crystal oscillator, a micro USB connection, an ICSP header, and 3 reset buttons.
The Yún distinguishes itself from other Arduino boards by its ability to communicate with the Linux distribution onboard, offering a powerful networked computer with the ease of an Arduino. In addition to Linux commands like the cURL, you can write your own shell and python scripts for robust interactions. The Yún is similar to the Leonardo with the ATmega32u4, except that it has Linux on board. (has built-in USB communication, eliminating the need for a secondary processor).
NB: Yun Release 5 The new Arduino Yun R5 differs substantially from the previous release in these features:
- The power supply system provides 5V on AREF;
- The layout has been modified, adding two holes for USB signals and two holes for GP6 and GPIO13(LED2).