The Arduino Yún allows makers to connect their projects to the internet by combining an Arduino-compatible microcontroller with an Linux-based microcomputer. The Bridge library simplifies communication between the two processors and enables functions like running processes, accessing files, exchanging messages, and creating HTTP clients and servers. This allows Yún users to leverage the power of Linux for internet connectivity while retaining the familiar Arduino experience.

1. Federico Vanzati
Arduino Yún: Internet for makers
f.vanzati@arduino.cc - Officine Arduino Torino

2. What is Arduino?
Federico Vanzati
f.vanzati@arduino.cc - Officine Arduino Torino
Arduino is an electronic prototyping platform that can sense the environment by
receiving input from a variety of sensors and can affect its surroundings by
controlling lights, motors, and other actuators.
COMMUNICATION
INPUT
USB
Serial
TWI
SPI
Analog
Digital
OUTPUT
Analog
Digital

3. Physical to Internet?
Federico Vanzati
Ethernet Shield
f.vanzati@arduino.cc - Officine Arduino Torino
WiFi Shield

4. Federico Vanzati
Limited number of connections
and modest performances
because all the code is
processed from the AVR
Client
Server
Managing the connection
f.vanzati@arduino.cc - Officine Arduino Torino
TCP/IP stack
only
can't handle secure
connections natively

5. Arduino Yún
Federico Vanzati
Https
SSL
SSH
AR9331
running OpenWRT
Usual Arduino experience
32U4
[Leonardo]
Tools offered by
the Linux system
f.vanzati@arduino.cc - Officine Arduino Torino
Advanced connectivity capabilities
thanks to Linux

6. Internet of Things (IoT)
Federico Vanzati
f.vanzati@arduino.cc - Officine Arduino Torino
Arduino: one of the first platform to offer the possibility to connect sensors and
actuators to Internet.
Many projects in different categories, for example:
●
Smart metering (photovoltaic, water flow and level, electrical comsumption)

7. Internet of Things (IoT)
Federico Vanzati
f.vanzati@arduino.cc - Officine Arduino Torino
●
Enviroment (radiation level, earthquake, air pollution)
●
Security & Emergencies (intrusion detection, fire/gas detection)

8. Internet of Things (IoT)
Federico Vanzati
f.vanzati@arduino.cc - Officine Arduino Torino
In a few years certainly these projects have influenced the definition of IoT.
The Arduino Yún follows the evolution of internet answering to the new
requirements of access to the web services.
The Arduino Yún gives you a lot of cool features.
Both WiFi and Ethernet
Enhanced connectivity (speed, more protocols, …)
Independent Web Server
Additional peripherals (USB host, SD card

9. What's on board?
Federico Vanzati
f.vanzati@arduino.cc - Officine Arduino Torino
Thanks to the Linux processor you have all the tools you normally use on
your compurer to develop code that lives on Internet.

10. Hardware Summary
Federico Vanzati
f.vanzati@arduino.cc - Officine Arduino Torino
Atmega32U4 (Leonardo)
AR9331 (OpenWRT)
Digital I/O Pins
20
Architecture MIPS @400MHz
PWM Channels
7
Ethernet
IEEE 802.3 10/100Mbit/s
Analog Input Channels
12
WiFi
IEEE 802.11b/g/n
Flash Memory
28 KB aval. USB
SRAM
2.5 KB
Card Reader Micro-SD only
EEPROM
1 KB
RAM
Clock Speed
16 MHz
Flash Mem.16 MB
Operating voltage: 5V
Type-A 2.0 Host/Device
64 MB DDR2

11. Processors Cooperation
Federico Vanzati
f.vanzati@arduino.cc - Officine Arduino Torino

12. Bridge Concept
Federico Vanzati
f.vanzati@arduino.cc - Officine Arduino Torino
As is common on Linux system, the console to access to the environment is
exposed on the Serial port.
The Arduino microcontroller (32U4) can control the Linux system through
the Serial port.
The Bridge Library has been developed to simplify the way the sketch can
manage the processes and the tools on the Linux side.
Arduino Library
Bridge
Python process on the Linux side
Started by the sketch

13. Bridge Features – communication protocol
Federico Vanzati
f.vanzati@arduino.cc - Officine Arduino Torino
The Bridge library simplify the communication between the two processors
using a protocol that numbers the packets, manage retrasmission and
timeout.
Classes of the library:
●
●
●
●
●
●
●
●
Storage
Process
Console
FileIO
Mailbox
HttpClient
YunServer
YunClient

14. Bridge Features – Shared Storage
Federico Vanzati
f.vanzati@arduino.cc - Officine Arduino Torino
With the Bridge library is possible to save data or
variables and share it with the Linux processor
using the shared storage, that has a KEY/VALUE
structure.

15. Bridge Features – Process
Federico Vanzati
f.vanzati@arduino.cc - Officine Arduino Torino
Process is the base class for all Bridge based calls for communicating with the
Yun's shell. It is not called directly, but invoked whenever you use a function that
relies on it.
Run Process
Process p;
p.begin("curl");
p.addParameter("http://arduino.cc/asciilogo.txt");
p.run();
Read Output
while (p.available()>0) {
char c = p.read();
Serial.print(c);
}
Serial.flush();
}

16. Bridge Features – Console
Federico Vanzati
f.vanzati@arduino.cc - Officine Arduino Torino
Console, based on Bridge, enables you to send information from the Yún to a
computer just as you would with the serial monitor, but wirelessly. It creates a
secure connection between the Yún and your computer via SSH.
#include <Console.h>
const int ledPin = 13;
int incomingByte;
void setup() {
Bridge.begin();
Console.begin();
while (!Console) ; // wait for Console port to connect.
Console.println("You're connected to the Console!!!!");
pinMode(ledPin, OUTPUT);
}
void loop() {
// see if there's incoming serial data:
if (Console.available() > 0) {
incomingByte = Console.read(); // read the oldest byte in the serial buffer:
if (incomingByte == 'H') { // if it's a capital H (ASCII 72), turn on the LED
digitalWrite(ledPin, HIGH);
}
if (incomingByte == 'L') {
// if it's an L (ASCII 76) turn off the LED
digitalWrite(ledPin, LOW);
}
}
}

17. Bridge Features – FileIO
Federico Vanzati
f.vanzati@arduino.cc - Officine Arduino Torino
FileIO is the base class for manipulating files and directories on the Linux
system directly from the 32U4.
If an SD card is inserted into the slot with an empty folder in the SD root named
"arduino". This will ensure that the Yún will create a link to the SD to the
"/mnt/sd" path.

18. Bridge Features – Mailbox
Federico Vanzati
f.vanzati@arduino.cc - Officine Arduino Torino
Mailbox Class allows you to exchange messages between the two processors,
putting them in two separate queues.

19. Bridge Features – Client/Server
Federico Vanzati
f.vanzati@arduino.cc - Officine Arduino Torino
HttpClient:
HttpClient extends Process and acts as a wrapper for common cURL commands
by creating a HTTP client in Linino
YunServer:
YunServer opens a listening socket on the Linino. You can choose to use it only
on localhost or expose the socket on the outside (with or without password)
YunClient:
YunClient is a TCP/IP client, implements the same APIs to connect, read and
write as in the Arduino Ethernet and WiFi Client libraries

20. WiFi Upload
Federico Vanzati
f.vanzati@arduino.cc - Officine Arduino Torino

21. “www” folder
Federico Vanzati
f.vanzati@arduino.cc - Officine Arduino Torino

22. Out of the Box experience
Federico Vanzati
f.vanzati@arduino.cc - Officine Arduino Torino

23. Temboo
Federico Vanzati
f.vanzati@arduino.cc - Officine Arduino Torino

24. Sands Project
Federico Vanzati
f.vanzati@arduino.cc - Officine Arduino Torino
Social&Smart is a research project using the housekeeping scenario to
experiment a pervasive Future Internet network that provides real services to a
wide population.

25. Demo
Federico Vanzati
f.vanzati@arduino.cc - Officine Arduino Torino