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Yun Shield adds OpenWrt and WiFi to Arduinos

May 12, 2016 — by Eric Brown 3,138 views

Arduino LLC released a shield version of its Arduino Yun SBC, letting you add WiFi and Linux to Arduino boards, along with Ethernet and USB ports.

The Arduino and Genuino Yun Shield peels off the OpenWrt-driven WiFi subsystem of the Arduino Yun SBC as a shield add-on, letting you add Internet access to other Arduino boards. The Arduino and Genuino Yun Shield is equipped with the same MIPS-based, 400MHz Atheros AR9331 WiFi SoC as the Arduino Yun and Arduino Yun Mini, the first Arduino SBCs to run Linux.

Arduino Yun Shield front (left) and back views
(click images to enlarge).

The open source, $50 shield lets you upload Arduino sketches to any Arduino or Genuino board that supports shields. Genuino is the brand name Arduino LLC has used for the last year for Arduinos sold outside the U.S., a complication resulting from legal disputes with rival forked entity Arduino Srl. The latter recently released its own WiFi-enabled Arduino with its Arduino Uno WiFi SBC, but like Arduino LLC’s new WiFi-enabled Arduino MKR1000, it doesn’t run Linux. Arduino Srl did, however, recently announce a WiFi-ready Arduino Industrial 101 SBC that runs the OpenWrt-based Linino.

Two views of the Yun Shield’s Carambola 2 WiFi subsystem
(click images to enlarge).

Arduino LLC’s new Yun Shield is the same size as the Arduino Yun and other Arduinos. Virtually all of the Shield’s functions are provided by its surface-mounted 8devices Carambola 2 piggyback module, which integrates the Atheros AR9331 SoC, along with 64MB of DDR2 RAM and 16MB flash. In addition to its onboard 802.11b/g/n radio, the module supplies a 10/100 Ethernet port and a USB 2.0 host port. The Carambola 2 has a second Ethernet controller that’s apparently left unused. The 3.3V Yun Shield interfaces to Arduino SBCs by means of SPI and serial connections. Most of the Yun Shield’s functions can be seen in page one of its schematic, below.

Arduino Yun Shield detail drawing (left) and schematic page 1
(click images to enlarge).

The Yun Shield is enabled by the Yun Web Panel and a new, dedicated YunFirstConfig sketch implemented in the latest Arduino Software (Arduino IDE) 1.6.9. YunFirstConfig allows you to manage your shield preferences and upload your sketch to an Arduino in .hex format. The Yun Shield provides the Bridge library found on the Yun to “extend your board capabilities using the Linux processor” says Arduino LLC.

The Yun Shield runs OpenWrt 15.05 (Chaos Calmer) within its WiFi module, “which offers an additional layer of security and a large amount of bug fixes over previous Yun distribution,” says Arduino LLC. The precompiled package list is said to exceed 4,000 packages. To find other packages, users can draw upon “the community provided repositories since the new release is fully modular (not a fork),” says the project.


The three-year old Arduino Yun is no longer sold by Arduino LLC, but a product page still appears at Arduino Srl’s website along with the Mini version. The Yun sells at outlets like Arrow and Adafruit at close to its original $69 price, and Studica has it for $64. Studica also offers Arduino Srl’s Arduino Yun Mini version for $61.

Further information

The Arduino and Genuino Yun Shield is available for $49.90 (€43.90) at the Arduino LLC website. More information may be found in the Yun Shield announcement and Yun Shield product page.

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One response to “Yun Shield adds OpenWrt and WiFi to Arduinos”

  1. LOGmaker says:

    Some good video’s about the yun.

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