TCP/IP Workshop

buildscc | 20 Feb 2012 | | workshops, events

Monday, Feb 20, 2012 @ 3:00pm in BUILDS

TCP/IP Workshop

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BUILDS Door Upgrade

New BUILDS room



Installed and working!

The desktop background stays the same at all times with a transparent terminal over it. On swipe, an alternative display based on the user id number is made using latex-beamer and converted to an image file that gets displayed with feh.

Currently, the display contains a 1984 reference. It has the potential to be expanded into different displays which could be rotated daily. Fun interactive door displays can be used for recruiting.

Door computer

Old door computer has been placed on the floor next to the door, but moving it into the ceiling would be a better option.

One can access the door computer by plugging in a USB keyboard and mouse into the back of monitor on the inside of the door. The old door computer now lives above the door in a trough like structure in the ceiling. DO NOT lift the ceiling tile in the corner above the door, it has the video/power cables on it; lift the one next to it. There is currently no fixed IP, but if one uses the keyboard/mouse, they can figure out the IP and log in remotely by SSH.

Card reader

The card reader has been physically installed, but the software backend needs to be revived.

Note: this reader contains magical black smoke that turns it into a keyboard, so make sure you have the active window if you are using it.

Currently, the card reader is used to display interesting “information” on the door screen. This is done in a screen session named “SwipeControl”, through 3 files (I’ll upload them soon!).

    This creates a full screen gnome-terminal on the door screen (nifty) and executes in it. 
    This script loops over waiting for a card swipe, generating interesting outputs, and displaying them on the door screen. 
  • troll.c
    This script turns off keyboard echoing to the screen and waits for a card swipe.   After a card swipe, it helps generate the output generated in the script.

Restarting Software in Case of Crash

  1. Figure out computers IP address.

  2. ssh to machine

  3. open the screen session
    screen -r SwypeControl

    if there is an error,

    screen -S SwypeControl
  4. Find relevent code in directory
    cd ~/swipe_control
  5. Run code in swipe_control directory
  6. Detach from screen session
    ctrl-a ctrl-d
  7. Test

Door strike

After doing some measurements and looking at tech sheets we have determined that this one will fit our door.

A request for money has been sent to the BUILDS secretary.

Upon arrival, the install should be quick.


Cable feedthrough is in place for door webcam.

Old BUILDS room

The door has been upgraded from its original RFID reader to a magstripe reader. The main cause of this is the cost of purchasing RFID tags. Now bu students may use bu ids to swipe into BUILDS and non-bu members may use any magstripe card they wish as their swipe card.

The door upgrade has also added a monitor outside of the door.

While right now it doesn’t have much use besides looking cool, it will eventually host announcements and general news.


Document Camera



Parts List

  • Arduino Uno
  • Servo Motor
  • Canon Camera (compatible with CHDK)


Powering the Camera

Servo Controller

The Arduino is used mainly as a controller for the servo and can be configured and issued commands over a Serial connection. The serial protocol used is extremely basic and relies on messages of three characters in length.

Command Bit Value Bit \n

Newline characters will always break and only the first two characters will ever actually be interpreted.

The following commands will set different position registers. Where n represents the ascii representation of a number.

Command Value
1 x
2 x
n x

The following command flags are recognized.

String Description
-t Trigger through array positions
-l List the values in int array positions
-d Toggle debug mode

Debug mode can be set using pin 12 on the Arduino. It is high active (when high debug mode will be on). Code is hosted at Document Camera Source Code

Camera Communications