Heather, Zach and myself created a one-bit mechanical adder (with a carry function) that runs on marbles. I found the basic design online and we modified it to our purposes. Zach and Heather used cardboard, foamcore and genius to prototype the flip-flop mechanism, then mounted each on a cardboard box, adding ramps and chutes to carry the marbles through the system. The flip-flops tilt to the left to indicate zero, and to the right to indicate one. So the top indicator denotes binary 1, while the bottom indicator indicates the carry bit, or binary two. Here’s a movie that I made of the adder in action, before I decked it out in rave-wear.
The plan going forward is to implement the design in wood, with additional bits (maybe eight or 16) and a subtraction function. It would be interesting to add a crank mechanism that carried the marbles back up to the top, perhaps in a single turn. This would allow for multiplication.
I’m working on a physical clock that also broadcasts time to the entire ITP floor via XBee ZigBee radio. The time signal can be picked up by any project on the floor that incorporates ZigBee, and used for anything from clock display to inter-project synchronization. The code is being written in PIC Basic Pro. At some point it may incorporate updates from NISTservers.
To pick up the signal at ITP, simply set the PAN address on your XBee to C or CC (the c is for clock). The signal is simultaneously broadcast to all 65,534 addresses within that network. PAN C is in a human-friendly format and PAN CC is formatted to be easily machine-readable.
This project interests me because it begins to explore how an object can share information on a network with other objects, creating a landscape of content from which other objects and people can benefit.
This moisture meter was based on a circuit from Forrest Mim’s excellent “Getting Started in Electronics” book. It uses an Ampere meter (not pictured) via a amplifying transistor to display the conductivity of the soil in a planter. And it works! This setup may be the basis for our primary plant sensors for ITPlant.
Samtec will sample small quantities of parts (usually no more than 10 of each. However their web site is confounding. If you want to find a part number, request or download a catalog first. When you are ready to order, use the Samtec Sample Form Put in the Item number and Quantity only. You don’t need the pull-down menus or Build a Part Number button at all.
Here’s some part numbers you may want:
Strips of 32 female headers with standard 100 mil breadboard spacing: SSA-132-S-T
Strips of 32 male headers with standard 100 mil breadboard spacing: TSW-132-07-G-S
Strips of 10 2mm female headers for XBee radios: MMS-110-01-L-SV
Strips of 20 2mm female headers for Lantronix MatchPort: MMS-120-01-L-SV
Sockets for 28-pin Arduino chips (low insertion force): ICA-328-ZSGG
May 15, 2007: Apparently the AT commands for the BlueSMiRF radios are a trade secret. BlueRadios requested that they not be posted. So, uh, don’t use them I guess?
Here’s the AT command set for BlueSMiRF modules. It’s tremendously handy to know all this stuff when working with the modules. I had high hopes that the SNIFF command would cause the module to make sniffling noises. No such luck.
At ITP on Thursday evenings, students teach students in hour-long sessions that we call DriveBys, because a lot of knowledge gets sprayed into the crowd in a short period of time. I just did one on the XBee ZigBee radios, covering the basics of applications, comparisons to other technologies, how to make one, advanced projects and some configuration in-depth. Here’s the XBee DriveBy presentation as a PDF. There is also a streaming video of the session available now, thanks to Dan Phiffer.
For Project Development Studio I’m working with Kate, Rebecca and Kati on a project to create an interaction network between live plants and people. Here’s our ITPlant notes.
