Arduino Yùn

The Arduino Yún development board is based on the Atmega32u4 and the Atheros AR9331. The Atheros processor supports all Linux distributions based on OpenWrt. In addition to standard Linux commands, custom shell or Python scripts can also be programmed on the board. The board features built-in Ethernet and WiFi support, as well as a USB-A port, a microSD card slot, and 20 digital input/output pins.

The memory of the Arduino Yún
The Atmega32u4 has a memory size of 32 KB, of which 4 KB is used for the bootloader. It also includes 2.5 KB of SRAM and 1 KB of EEPROM. The memory of the AR9331 is not embedded in the processor; the RAM and storage are connected externally. This gives the board 64 MB of DDR2 RAM and 16 MB of flash memory.

Programming capabilities
The development board can be easily programmed with the Arduino software. Additionally, the bootloader of the Atmega32u allows for direct uploading of new code without the need for an external programming device. The bootloader communicates via the AVR109 protocol and can also be bypassed through the In-Circuit Serial Programming header.