learning the ropes

things I made at ITP and after: sketches, prototypes, and other documentation

Wednesday, February 28, 2007

Chip Select on AD5206

Ai-Chen and I did a bit of rewiring on the Secret Tree circuit board. One of the problems we had last week was that all of the ground wires for the LEDs on the trees were connected to two PCB terminals. I didn’t purchase enough terminal at RadioShack so that every pair could have a ground of its own. This not only made things messy, but it also made the connections suspect.

Updated Circuit 002

The other major discovery I made which explained much of the circuit’s random (unintended) behavior was that the two AD5206 chips interfered with one another. I plugged a single LED into each of the twelve outputs (across the two chips) and found that a simple test program didn’t operate properly when both chips were running. As soon as I disconnected the three data lines (CLK, SDI, and CS) from the second chip, the first chip would work properly. I wondered if there might be some sort of “floating” condition when the two chips were used together. Since CLK and SDI were shared, I hypothesized that CS was likely the culprate. To test this, I added 10K pull-down resistors on the chip selects of both chips. It worked! The test program dimmed the lights in the proper sequence rather than skipping around randomly on the third and fourth outputs.

posted by Michael at 10:02 pm  

Monday, December 11, 2006

- Modified MAX patch to playback samples instead of routing notes to a MIDI synthesizer
(full comments are found in 12/1 notes)

posted by Michael at 9:32 pm  

Saturday, December 9, 2006

User Testing

User Test - Kyveli -8 User Test - Kyveli -12 User Test - Stephanie-2

posted by Michael at 8:05 pm  

Tuesday, November 28, 2006

- Continued construction using the perfboard/shrink tubing sensor package and finished two shoe prototypes
- User Test – Patricia (using foamboard prototype + Korg synth module)
- Felt that more sensitivity was needed. She found it difficult to trigger the samples without stomping really hard
- Didn’t like bass drum on the heel; felt it would be more natural on the front
- Cannot tell where the sensor is — perception is that it is close to the center of the shoe
- Feels the system is more responsive with the 10k resistor than with the 2k
- Could play either sitting or standing
- Would like to play along with some other music

posted by Michael at 10:51 pm  

Monday, November 27, 2006

Assembling Portfolio

We have something like three or four weeks until the end of the semester. I’ve been working to assemble my project portfolio for Spatial Design. As I flipped through all of the pictures and notes I’ve taken, I started feeling unsure of how to organize all of it into a neat package. How do I sum up “me” or what “I” have to offer?

I started out searching for other ITP Spatial Design portfolios and ended up discovering e-Portfolios. I managed to restrain myself before diving headlong into the world of personal content management systems. There is something about information storing, sorting, searching, and organization that grabs my attention. As I was preparing to start classes at ITP I gave my then “old” (meaning several months) wikidpad system a shake for Evernote. I tried out GoBinder, Windows Journal, and most recently OneNote. This has almost been an obsession for me. How do I store the information I collect each day. How do I organize it so I can find it again. How do I display it so others can get a sense of what I’ve been doing?

posted by Michael at 9:54 pm  

Sunday, November 26, 2006


Shinyoung and I are working on our final project and preparing it for submission for the ITP 2006 Winter Show.


We had some difficulties on Wednesday afternoon, which stemmed from a bug in Processing’s offscreen drawing code. We are drawing our kaleidoscope images offscreen in order to avoid the overhead of computing the positions of all of the “particles” in our system. By drawing a small particle system offscreen and capturing the bitmap image of it each frame, we can manipulate the bitmap using Processing’s image handling functions and avoid iterating through massive collections of particle objects.

Shawn Van Every came to our assistance and helped me dig through some of the Processing source code in order to locate a potential workaround. He found that by changing the offscreen rendering method from P2D to Java2D, we could safely use the “rect” function which had previously caused Processing to choke.

posted by Michael at 11:01 pm  

Saturday, November 25, 2006

- Problem: Sensitivity Training. It is difficult to get the sensors to trigger samples consistently. We’re concerned after studying the FSR datasheet and application notes that we might be saturating the sensors and going outside of their useful operating range. We try replacing the 10k resistors in the sensors’ voltage dividers with 2k resistors. We are also trying to eliminate the opposite problem: standing still on the prototype triggers samples. Is the circuitry too sensitive?

- Problem: The MAX patch plays two notes simultaneously. We work to debug this issue by breaking the MAX patch into sections… first by printing the received note data, then watching this data as it propagates through successive objects in the patch.

posted by Michael at 11:03 pm  

Tuesday, November 21, 2006

- Breakthrough: Tried sandwiching sensors between layers of foamboard in the hopes of avoiding sensor wear and exposed wiring. Much of the discussion continues to focus around protecting the sensors.

posted by Michael at 7:48 pm  

Sunday, November 19, 2006

Projection Experiments

Allistar and I did some experiments this afternoon for our final project in Spatial Design. It’s going to be a “green” place of refuge.

posted by Michael at 9:48 pm  

Thursday, November 16, 2006

- I ordered connector samples from Samtec: female headers so we could prototype the FSR strain relief packages and 6-position modular jack connectors in the event we want to build printed circuit boards for this project.

posted by Michael at 10:11 pm  
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