Hands on the Arduino Yún
Video 1: Introduction to the Arduino Yún by Massimo Banzi and David Cuartielles
First things first, you need to plug the Yún to a power source prior to using it. There are 3 ways to deliver power to the Yún. The first option is simply through USB. This is typically done by connecting the board to a PC our a USB hub via Micro-B USB cable. The second option is through the ethernet plug since the Yún does support Power over Ethernet (PoE). The third solution is to use an external electric power source through the Vin and Ground pins. But then, you need to be careful because the there is no built in 5V regulator. If you power your Yún with more than 5V, you will likely damage it. A simple way to avoid this is to use a 3LR12 lantern battery which delivers 4.5V.
Once the Yún is connected to a power source, few seconds are required to Linino to boot. Then, you’ll see a Wifi network with a name starting with “Arduino Yun”. The full name looks like Arduino Yun-XXXXXXXXXXXX, where the Xs are alphanumerical characters. The Yún acts by default as an access point. So, you can connect your computer to the ArduinoYun Wifi and start interacting with the Yún.
You can replace this configuration and make the Yún connect to another Wifi network. This change is very easy likewise most of the setup. All you have to do is to access the configuration web interface using a web browser that opens the http://arduino.local address.
Checking the Connection
Once connected, you can open a terminal and ping the board to check that the Linino is ready by evaluating:
The arduino.local refers to your board in the local network. So, if you replace its name (through the configuration web interface) to say myYun, you should be using myYun.local instead of arduino.local. Anyway, if the everything is ok, you should get an answer similar to the following:
PING arduino.local (192.168.240.1): 56 data bytes
64 bytes from 192.168.240.1: icmp_seq=0 ttl=64 time=1.225 ms
64 bytes from 192.168.240.1: icmp_seq=1 ttl=64 time=2.502 ms
64 bytes from 192.168.240.1: icmp_seq=2 ttl=64 time=2.551 ms
Logging into Linino
The Linux carried by the Yún is a distribution based on OpenWRT named Linino (also referred to as OpenWrt-Yún). Logging into Linino can be done as with any Linux through ssh from a terminal of a computer that is on the same network as the Yún. The default user is root. So, to login in you need to type the following command line:
The first time you try to connect to your Yun from a computer, the terminal will reply with a message like this :
The authenticity of host 'arduino.local (192.168.240.1)' can't be established.
RSA key fingerprint is c6:4a:45:ab:51:56:17:08:3a:04:54:14:ad:82:f8:fa.
Are you sure you want to continue connecting (yes/no)?
Type yes at this prompt to continue the process. You’ll get a response that says:
Warning: Permanently added 'arduino.local,192.168.240.1' (RSA) to the list of known hosts.
Next, you will get prompted to provide the password. By, default it is arduino. Of course you can change it through the web interface too. Et voilà, you’re in! You will quickly notice that Linino is a stripped down Linux. For example, there is no man by default. So, expect some adjustments depending on your project. Still, you can expand the default setup by installing extra packages using the package manager opkg.
Resetting the Yún
The Yún offers different levels of reset:
- To reboot the microcontroller (Leonardo part) only, press the 32U4 RST button (see Picture 1).
- To reboot the linux system only, press the YÚN RST button near the analog input pins.
- If you want to reset the Wifi and make the Yún revert to its original Wifi setup (i.e. Wifi host spot with SSID Arduino Yun-XXXXXXXXXXXX), press the button labelled WLAN for more than 5 seconds. The WLAN button is located near the host USB connector (the big one). Note that while the WLAN button is pressed the WLAN led will blink in blue.
- If you did mess up with your board configuration, or you simply need a fresh setup for a new project or experiment you can do a full reset and make the Linino go back to its default state. Press the WLAN button but this time for more than 30 seconds.
Picture 1: Reset Buttons of the Yún