Meeting Minutes for 2012-02-22

buildscc | 22 Feb 2012 | | meeting-minutes


Kyle Brogle

  • Project updates…Much was done this weekend!

Dan Gastler

  • The door still runs on the old code. Notice the camera above the table? It gives a live stream (.mpeg 4 video) from the camera outside the door. This was hacked together from an old thinkpad that Danny found, together with work from both Allan and Dan.

Chris Woodall

  • BUILDS bot has spawned a minibot named 12ounce. Made from the casing of an old IR motion sensor, it’s a good start for the BUILDS bot project to get used to coding/ making (working) motor controls.

Monica Gribouski

  • Toby from IS&T came in and taught BUILDS multitouch how to ame polish their acrylic, so further progress is now blocking on the acquistion of new materials.

Chris Woodall

  • BUILDS has a table reserved at the Cambridge Maker Fair (on April 20th). Contact Chris/Kyle if you have any projects that you’d like to contribute.

(KDE) Jeff Crowell

  • The laser arrived for BUILDS drawbot, so work will continue this weekend. Contact Jeff if you’re interested.

George Silvis / Anthony Inzero

  • Many thanks to George and Zero for traveling to Micro-Center and (successfully) building three new BUILDS computers. So sayeth Baron von Computer: if you need something installed on any of the computers, talk to George or Kyle.

Liam Wang

  • VGC is still going, but temporarily blocking on Liam surviving theatre Hell Week. If you’re interested in helping out, contact Liam.

Allan Wirth

  • BUILDS Coding Bee: (Think first annual Python Bee). The acceptable languages are C, Python, and Haskell. The grand prize is a BUILDS ceiling tile with your face on it (to remain in BUILDS). If you have a language that you really want, contact Allan or George.

Dan Gastler

  • Musical Stairs:
    • New goals are to solder on two new jacks and test two new sensors. Work will begin on saturday at 3pm.

Danny Cooper

  • Work on BUILDS document camera is still in progress, but milestones are being blocked by terrible manufacturer documentation.

Chris Woodall

  • Thanks to Ian and his generous typewriter donations, BUILDS typewriter can now begin. Hacking will commence this saturday at 2pm.

Valerie Young

  • Meta Topics:
    • Funds are roughly at 600 of free-use money. If you need funding for your project, contact Valerie for other means (Jim Stone, SAO, etc). For BUILDS officer elections, the format is heading toward having a secret veto ballot (in person, not over email), and having tickets of officer groups as opposed to voting for officers individually.

Chris Woodall

  • If you want to participate in a BUILDS arduino/ soldering workshop, talk to Chris so he can get a rough idea of interest.

Document Camera

buildscc | 22 Feb 2012 | | projects



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

TCP/IP Workshop

buildscc | 20 Feb 2012 | | workshops, events

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

TCP/IP Workshop

BUILDS Door Upgrade

buildscc | 20 Feb 2012 | | projects

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.

Multitouch Table

buildscc | 16 Feb 2012 | | projects

Current Status

Acrylic sheet obtained; in the process of sanding/flame-polishing the edges.

Meetings are vaguely set on Sundays around 2:30.


There are a variety of ways to approach building a multitouch table, but for this project we will be using Frustrated Total Internal Reflection (FTIR). FTIR functions by shining Infrared (IR) light into the sides of an acrylic sheet, where the light is reflected. As soon as a surface hits the top of the acrylic the IR light is scattered downward through the sheet where it is picked up by an IR camera. Any surface hitting the sheet shows up to the camera as “blobs” of light, which can be tracked using software. Furthermore, a projection surface is placed on top of the acrylic sheet. It serves two purposes: one, to act as a screen for the multitouch table, so the projector (set underneath the acrylic) has a surface to project onto, and two, so that, coupled with a layer of silicone sealant between the acrylic and the projection surface (the compliant layer), the IR camera can pick up on motion rather than static points. For example, when a finger is pressed and slid across the surface, the compliant layer makes the projection surface briefly stick and slide, appearing to the IR camera as a short trail. This, rather than the acrylic sheet alone, allows for ease in tracking moving touches.


First, the edges of the acrylic must be sanded—the IR LEDs will not project properly into saw-cut acrylic edges. Next, the LEDs must be sautered together in a line, spaced about an inch apart from each other, so as to line all edges of the acrylic sheet. They can be taped or otherwise attached to the acrylic. To create the compliant layer, silicone sealant will be rolled onto a sheet of vellum using a foam roller in order to distribute it evenly. The silicone will be allowed to dry, and this process will be repeated at least twice more. Finally, the vellum can be placed on top of the acrylic.

In order to ensure the camera picks up only IR light, one can either purchase an IR camera, or open the camera and remove the IR filter, replacing it with a visible light filter. A visible light filter can be purchased, or one can be created using the magnetic tape inside of a floppy disk.

Finally, the projector will be set up either directly below the acrylic, or mirrors will be used to reflect the projected image onto the projection surface. A cabinet will be built out of wood to house the IR camera, projector, and multitouch surface, and a wooden baffle will be built around the top of the multitouch surface so that IR light directly from the IR LEDs does not shine at the user. The computer running the multitouch software will either be housed in this cabinet, or will be attached and set up separately for optimal ease of testing. Touchlib, an open source multitouch library, will be used for most software purposes until a software development phase has begun.


Project Leader: Monica Gribouski

Meeting Minutes for 2012-02-15

buildscc | 15 Feb 2012 | | meeting-minutes



  • If you spill any liquid in BUILDS, you must clean the WHOLE room

Kyle Brogle

  • Wireshark Workshop
    • Meeting on monday went great, and many thanks to all those who showed up. There will be more problems to be worked on, so check your email for future updates and meeting times. Who would be interested in a mini CTF for BUILDSers? Speak up!

Anthony Inzero / Christopher Woodall

  • BUILDS Bot
    • A good amount of the parts are in, so work will be begin (very) soon. If you want to join in, come by BUILDS around saturday 1pm (and onward).

Valerie Young

  • Musical Stairs
    • Stairs parts have arrived, and further progress is blocking on basic tests on the parts. Will be testing more tonight/this weekend

Allan Wirth

  • Music server hackathon this saturday! Come and hack things together to make the music server more stable, and maybe add some features.

Dan Gastler

  • BUILDS Door Upgrade
    • After working this weekend, the door is operational again. Project door is becoming ever more epic, so you should get involved.

Monica Gribouski

  • Multitouch Table
    • Toby is coming in this weekend to teach us how to “fame-polish” the acrylic so sanding doesn’t need to happen.

Danny Cooper / Christopher Woodall

  • Document Camera
    • Much work has been done on the Document Camera this past weekend. Further work includes mounting issues and some scripting. If you want to help out, work will continue this weekend

Christopher Woodall

  • Tweeting Typewriter
    • Type into a typewriter, it reads the message, and tweets it for you! There is talk about working with the BU postsecret club, for collaborative awesomeness. Prototyping once Ian Felder brings one of his typewriters to BUILDS
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