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Versione delle 19:18, 2 mag 2014

Arduino Yun Basics

This tutorial covers a little introduction to video recording with Arduino Yun and a USB webcam. No Arduino code in this first part, only some linux embedded configuration on the awesome Arduino Yun board!

I assume that the reader has a pc or a mac (named Bob) and an Arduino Yun, named Arduino. Moreover, I suppose the reader is quite familiar with the computer in general and know a little bit of shell/linux commands. In particular I in my case Bob is amac os/x and, and everything is starting with an iTerm2 session where everything begin with a dollar sign ($)..

Before starting

Assure we have:

Installed and working Arduino Ide version 1.5.6-r2.
Configured Arduino Yun board. See Basic Arduino Yun wireless configuration.

Let's become confident with the board

arduino.local does not always resole, so safely to use the ip number (192.168.240.1, for initial configuration) then the host name.

To log into the yun via ssh (from Bob shell): $ ssh root@192.168.1.13

Now you're logged in the Arduino Yun linux board. We are inside an embedded linux machine, in particular a child of OpenWrt. For briefness I will differentiate what is happening inside the iTerm session in Bob with $ and what is happening inside the yun shell accessed via ssh with ~.

See which distribution, kernel version, etc:

   ~ cat /proc/version
   Linux version 3.8.3 (federico@smilzo) (gcc version 4.6.4 20121210 (prerelease) (Linaro GCC 4.6-2012.12) ) #8 Mon Aug 19 16:22:39 CEST 2013

See if the micro sd card is already mounted:

   mount

I won't specify every time the path but I'm going to use the micro sd card for storing videos or pic rues from the welcome.

Install some useful packages for video and webcam:

   ~ opkg update
   ~ opkg install kmod-video-uvc kmod-video-pwc kmod-input-core
   ~ opkg install libjpeg fswebcam
   ~ wget http://www.custommobileapps.com.au/downloads/mjpg-streamer.ipk
   ~ opkg install mjpg-streamer.ipk
   ~ opkg install ffmpeg ffserver
   ~ opkg install python-openssl

After each installed package, to see free space on the hard disk:

   ~ df -h
   Filesystem                Size      Used Available Use% Mounted on
   rootfs                    7.5M      4.9M      2.6M  66% /
   /dev/root                 7.0M      7.0M         0 100% /rom
   tmpfs                    29.9M    372.0K     29.5M   1% /tmp
   tmpfs                   512.0K         0    512.0K   0% /dev
   /dev/mtdblock3            7.5M      4.9M      2.6M  66% /overlay
   overlayfs:/overlay        7.5M      4.9M      2.6M  66% /
   /dev/sda1                 7.4G    848.0K      7.4G   0% /mnt/sda1

To run a python server

   ~ python -m SimpleHTTPServer

See if python server (or the streaming server, vide infra) is running (from Bob),

   $ nmap 192.168.1.13
   
   Starting Nmap 6.40 ( http://nmap.org ) at 2014-04-30 13:03 CEST
   Nmap scan report for 192.168.1.13
   Host is up (0.19s latency).
   Not shown: 995 closed ports
   PORT     STATE SERVICE
   22/tcp   open  ssh
   53/tcp   open  domain
   80/tcp   open  http
   443/tcp  open  https
   8000/tcp open  http-alt
   
   Nmap done: 1 IP address (1 host up) scanned in 39.77 seconds

With standard usb uvc cam

To see the stream (from Arduino to Bob):

   ~ mjpg_streamer -i "input_uvc.so -d /dev/video0 -r 640x480" -o "output_http.so -p 8080 -w /mnt/sda1"

Then open "http://arduino.local:8080/?action=stream" in a brower (inside Bob)

To shoot a photo (on Arduino):

   ~ fswebcam test.png

and to see the photo via http request from Bob, just start a

   ~ python -m SimpleHTTPServer

in the directory where the photo is saved and access it by browsing (from Bob) to "192.168.1.13/test.png"

With PS3 Eye webcam

References