ChApTEr 2 ■ hArdwArE for IoT SoluTIonSThe Yún has a USB host controller as well as both WiFi and Ethernet networking. Indeed, you can use
the WiFi capabilities to form a wireless access port, making it possible for IOT solutions to host their own
WiFi-connected devices. Like the Zero, this board runs on 3.3V, requiring you to select your components and
shields carefully to ensure you do not damage the board. Figure 2-2 depicts the Arduino Yún.
The Yún is not a board for everyone. However, if you need to be able to combine the use of Arduino
shields with more powerful scripts written in Python, the Yún is perhaps a good choice for combining the
power of Python with the versatility of Arduino-compatible components and shields. There are other boards
that do this a bit better, but most do not include the WiFi access port capability. If you need or want to
provide a powerful wireless access port feature in your solution that can run any of your Arduino sketches,
the Yún is a good choice.
So far, I’ve used my Yún to create discrete WiFi networks for forensics and diagnosis of networking
problems. Using the Yún as an access port permits me to do things I would not do on my own WiFi network.
After all, if things go bad, I can just reset my Yún and try it again. It is far more risky to try that with your own
wireless access router.
You can find specific documentation for the Arduino Yún at http://arduino.cc/en/Guide/ArduinoYun.
Arduino Leonardo
The Leonardo board is an evolution of the older, Uno-based boards. Although it supports the standard
header layout, it doesn’t support some of the older shields. However, it adds a faster processor and a USB
controller that allows the board to appear as a USB device to the host computer. The newer ATmega32u4
processor has 20 digital I/O pins, of which 12 can be used as analog pins and 7 can be used as a pulse-width
modulation (PWM) output. It has 32KB of flash memory and 2.5KB of SRAM.
The Leonardo has more digital pins than its predecessor but continues to support most shields. The
USB connection uses a smaller USB connector. The board is also available with and without headers.
Figure 2-3 depicts an official Leonardo board.
Figure 2-2. Arduino Yún