====== About ======
It is very simple demonstration how to use Carambola as rover platform with video feedback. It could be nice toy to build in couple of hours.

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====== Hardware ======
I used very simple hardware setup. 
Key components are [[http://www.pololu.com/catalog/product/1112|motor controller]], [[http://www.pololu.com/catalog/product/1574|47:1 gearmotors]], [[http://www.pololu.com/catalog/product/1557|wheels]], UVC webcam supported by mjpg_streamer and of course Carambola. 

===== Connection =====
  * Webcamera - just plug to USB port.
  * Motor controller - connect to Carambola serial port. Use 2(TX) and 5(GND) pins. (see diagram below)
  * Motors - see diagram below. Connect 2 motors in parallel. 

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===== Building system =====
  * Build image with video support (see [[carambola:demo_projects:usb_webcam|USB webcam]])
  * Flash fresh image to Carambola ([[openwrt:firmware|uploading firmware]])
  * Setup wireless connection [[openwrt:recipes:wifi_settings|Wifi intialization]]
  * Set system password (we will need this later for ssh access)

  passwd root

  * install package for video streaming

  opkg update
  opkg install mjpg-streamer

  * edit ''/etc/config/mjpg-streamer'' if you like. Default settings works fine. 

  config mjpg-streamer core
        option device           "/dev/video0"
        option resolution       "400x200"
        option fps              "25"
        option port             "8081"
        option enabled          "true"

  opkg install ser2net

  * edit /etc/ser2net.con - comment all lines at the end of file and add this one

  2002:raw:600:/dev/ttyS1:115200

  * edit ''/etc/rc.local'' file to add ser2net autostart functionality 

  ser2net
  exit 0

  * Now you are able to connect to Carambola's serial port via telnet 2002 port. 
  * You can now reboot your Carambola to see if everything works.

  reboot


===== Testing =====
==== Video ====
  * open favorite network stream player (I have tested vlc and chrome web browser - both worked) and paste url ''http://192.168.0.112:8081/?action=stream''
  * For VLC make sure you setcaching to 0ms instead of 1200ms (default) to reduce video lag

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==== Controls ====
  * To test if robot responds to commands
    * Forward   ''0x8A, SPEED, 0x8D, SPEED''
    * Backwards ''0x88, SPEED, 0x8E, SPEED''
    * Left	''0x88, SPEED, 0x8D, SPEED''
    * Right     ''0x8A, SPEED, 0x8E, SPEED''
  * Before you start playing, you should press setup button. It sends safety configuration to motor controller
    * Serial port idle timout = 0.25s ''0xAA, 0x0A, 0x04, 0x03, 0x01, 0x55, 0x2A''


==== ToDo ====
This quick example illustrates how to interface motor controller and webcam. Further you could connect these items to build autonomous vehicle.

  * gps
  * counter on all wheels
  * sonar
  * robotic arm
  * lights
  * wifi booster
  * volt meter
  * wider angle lens
  * smaller (lipo battery)

==== Notes ====
  * I ordered 47:1 gear motor (285 RPM), which is still a bit to fast. So, if you plan to replicate this by your self, consider buying germotor with 75:1 or even 99:1 ratio.
  * After you reboot Carambola, connect to it using ssh and type ''ser2net'' this will enable communication to motor controller.
  * It is good idea to close all electronics and put external led's to indicate wireless signal level and other status signals.

==== More images ====
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