# Arduino Yún > Hybrid Arduino/Linux board combining ATmega32U4 with a MIPS-based Linux SoC, 802.11bgn WiFi, Ethernet, USB host, and microSD — enabling cloud-connected Arduino sketches and over-the-air programming. ## Quick Facts - **Brand:** Arduino - **Board Type:** dev-board - **Price:** ~$74.95 - **Product Readiness:** developer - **CPU:** ATmega32U4 @ 16 MHz,Atheros AR9331 MIPS @ 400 MHz - **CPU Architecture:** AVR,MIPS - **CPU Cores:** 1+1 - **RAM:** 2.5 KB (MCU),64 MB DDR2 (Linux) - **Flash:** 32 KB (MCU),16 MB SPI (Linux) - **Power:** 5V via Micro USB or PoE (802.3af) - **Operating Voltage:** 5V - **Dimensions:** 73 × 53 mm - **SD Card:** microSD ## Connectivity - **Wifi:** 802.11 b/g/n - **Ethernet:** 10/100 Mbps PoE ## Open Source - **Firmware:** Yes - **Schematics:** Yes - **PCB Layout:** Yes ## Compatible Firmware arduino, platformio ## Use Cases - iot - networking - home-automation - cloud-connected - data-logging ## Components - **ATmega32U4** (mcu): 8-bit AVR with native USB at 16 MHz, 32KB flash, 2.5KB SRAM — [Datasheet](https://openhardware.directory/r?to=https%3A%2F%2Fww1.microchip.com%2Fdownloads%2Fen%2FDeviceDoc%2FAtmel-7766-8-bit-AVR-ATmega16U4-32U4_Datasheet.pdf&ref=openhardware.directory&product=arduino-yun&source=md-export) - **Atheros AR9331** (soc): MIPS-based SoC at 400 MHz running OpenWrt Linux with integrated 802.11bgn WiFi, 64MB DDR2 RAM, 16MB flash — [Datasheet](https://openhardware.directory/r?to=https%3A%2F%2Fwww.openhacks.com%2FuploadsProductos%2FAR9331_datasheet.pdf&ref=openhardware.directory&product=arduino-yun&source=md-export) ## Protocols - **UART**: TX: D1, RX: D0 - **SPI**: MOSI: D16, MISO: D14, SCK: D15, SS: D10 - **I2C**: SDA: D2, SCL: D3 - **USB** ## GPIO Map | Pin | Name | Type | Functions | |-----|------|------|-----------| | D0 | UART RX, External Interrupt 2 | UART | digital-input, digital-output, interrupt | | D1 | UART TX, External Interrupt 3 | UART | digital-input, digital-output, interrupt | | D2 | I2C SDA, External Interrupt 1 | I2C | digital-input, digital-output, interrupt | | D3 | I2C SCL, PWM, External Interrupt 0 | I2C | digital-input, digital-output, pwm, interrupt | | D4 | Digital I/O, Analog Input (A6) | — | digital-input, digital-output, analog-input | | D5 | Digital I/O, PWM | — | digital-input, digital-output, pwm | | D6 | Digital I/O, Analog Input (A7), PWM | — | digital-input, digital-output, analog-input, pwm | | D7 | Digital I/O, Linux bridge reset | — | digital-input, digital-output, interrupt | | D8 | Digital I/O, Analog Input (A8) | — | digital-input, digital-output, analog-input | | D9 | Digital I/O, Analog Input (A9), PWM | — | digital-input, digital-output, analog-input, pwm | | D10 | SPI SS, PWM | SPI | digital-input, digital-output, pwm | | D11 | Digital I/O, PWM | — | digital-input, digital-output, pwm | | D12 | Digital I/O, Analog Input (A11) | — | digital-input, digital-output, analog-input | | D13 | Onboard LED, PWM | — | digital-input, digital-output, pwm | | D14 | SPI MISO | SPI | digital-input, digital-output | | D15 | SPI SCK | SPI | digital-input, digital-output | | D16 | SPI MOSI | SPI | digital-input, digital-output | | A0 | Analog Input / Digital I/O | — | analog-input, digital-input, digital-output | | A1 | Analog Input / Digital I/O | — | analog-input, digital-input, digital-output | | A2 | Analog Input / Digital I/O | — | analog-input, digital-input, digital-output | | A3 | Analog Input / Digital I/O | — | analog-input, digital-input, digital-output | | A4 | Analog Input / Digital I/O | — | analog-input, digital-input, digital-output | | A5 | Analog Input / Digital I/O | — | analog-input, digital-input, digital-output | ## Available Software - **[Arduino IDE]()** (open-source) - **[OpenWrt Linux]()** (open-source) ## Description ## Overview The Arduino Yún (meaning "cloud" in Chinese) is a unique board that combines two processors: an ATmega32U4 Arduino microcontroller and a Atheros AR9331 MIPS-based Linux SoC running OpenWrt. This dual-processor architecture allows developers to write standard Arduino sketches on the 32U4 side while leveraging a full Linux environment for web services, network connectivity, and complex processing on the Linux side. The ATmega32U4 runs at 16 MHz with 32KB flash and 2.5KB SRAM, providing familiar Arduino compatibility for hardware interfacing. The AR9331 runs at up to 400 MHz with 64MB DDR2 RAM and 16MB SPI flash, hosting an OpenWrt Linux system that provides WiFi (802.11bgn with AP/router capability), Ethernet via PoE, USB 2.0 host, and microSD card support. The two processors communicate via a Bridge library, allowing Arduino sketches to invoke Linux commands, read web APIs, and publish data to cloud services. The board can be programmed wirelessly over WiFi using Arduino IDE 1.5.4+, eliminating the need for a physical USB cable in deployed installations. The Yún was a pioneering board for IoT development at a time when WiFi-enabled microcontrollers were uncommon, enabling projects like weather stations, security cameras, and smart home controllers that required both real-time hardware control and internet connectivity. ## Where to Buy - [Amazon US](https://openhardware.directory/r?to=https%3A%2F%2Fwww.amazon.com%2Fdp%2FB00PGD2CTS&ref=openhardware.directory&product=arduino-yun&source=md-export) — $69.90 ## Resources - [product](https://openhardware.directory/r?to=https%3A%2F%2Fwww.adafruit.com%2Fproduct%2F1498&ref=openhardware.directory&product=arduino-yun&source=md-export) - [wiki](https://openhardware.directory/r?to=https%3A%2F%2Fdocs.arduino.cc%2Fretired%2Fboards%2Farduino-yun&ref=openhardware.directory&product=arduino-yun&source=md-export) ## Tags `arduino`, `atmega32u4`, `linux`, `wifi`, `iot`, `openWrt`, `mips`, `cloud` ## Images ![Arduino Yún](https://nbg1.your-objectstorage.com/openhardware-directory/entities/arduino-yun/0c2257730ec4.jpg) ![Arduino Yún](https://nbg1.your-objectstorage.com/openhardware-directory/entities/arduino-yun/143fa73ae489.jpg) --- [View full device page](https://openhardware.directory/devices/arduino-yun)