Month: August 2011

Adam and I have been talking for a while about a little collapsible photo studio for posting images to the blog and to instructables. Well, its here now, for all to use!  All I did was take a roll of photo background paper and mount it semi-permanently above our main workbench.  To use it, pull down a length of paper to cover the desk, then turn on the fluorescent work-lamps. The paper rolls back up out of the way when you aren’t using it.  Here are some spiffy test shots I took of one of Chris’ sculptures.  Neat, huh? 

We’re going to be trying to make our own ferrofluid on Tuesday night to have available to play with on Wednesday night. If our efforts are successful, then for Open House we’ll show you how to make it using old audio cassette tapes and acetone. I don’t know what kind of results to expect, but here’s a video giving an idea of the extreme:

I downloaded Scratch to play with it after a presentation on E-Textiles at UPenn back in April.  I found it kind of interesting, and I was particularly interested in the “Scratch Sensor Board“, which provides a way to send physical signals into Scratch scripts and have Scratch respond to them.  It’s a pretty simple protocol, and I filed away “build a Scratch sensor board” as one of those projects that I might do … someday.  Well, nothing like being stuck at home during a major weather event to crank up the boredom level to the point that ya gotta do something.  So, courtesy of Hurricane Irene, here’s a DIY Scratch Sensor written as an Arduino Sketch.

This sketch uses information that you can download here.  You may need to use the Scratch Board Watcher to get things cooking 100%.  For example, this is how I learned that the sense of the Button input is inverted.

/* 
This code emulates a Scratch Sensor board
*/

// --- sends serial bytes corresponding to a signal with value given by "data"
//     coming from the channel designated by "channel"
//     data is in the range 0 .. 1023 inclusive and generally gets mapped to the range 0 .. 100 by Scratch
void sendScratchData(int channel, int data);

int buttonPin = 2;   // Change this if you want to use some other pin for the Button input. Just don't use pins 0 or 1.
int ledPin =  13;    // LED connected to digital pin 13. I used this just to monitor the request/response traffic

void setup() {
  pinMode(buttonPin, INPUT);
  pinMode(ledPin, OUTPUT);   

  // Set baud rate expected by Scratch sensor:
  Serial.begin(38400);
}

void loop()
{
  int inByte;
  // if we get a valid byte, send the scratch data
  // Technically, we should check that the value is a 0x01 byte,
  // but, meh ...
  if (Serial.available() > 0) {

      // toggle the LED so that we can see the request/response activity
      // this is optional, really
      digitalWrite(ledPin, ~digitalRead(ledPin));

      // get incoming byte:
      // we really should test the value, but meh++
      inByte = Serial.read();

        sendScratchData(0,analogRead(0)); // Resistance "D" is mapped to Analog 0
        sendScratchData(1,analogRead(1)); // Resistance "C" is mapped to Analog 1
        sendScratchData(2,analogRead(2)); // Resistance "B" is mapped to Analog 2
        sendScratchData(3,digitalRead(2) * 128); // Button is mapped to Digital 2
        sendScratchData(4,analogRead(3)); // Resistance "A" is mapped to Analog 3 
        sendScratchData(5,analogRead(4)); // light is mapped to Analog 4 (signal is inverted)
        sendScratchData(6,analogRead(5)); // sound is mapped to Analog 5
        sendScratchData(7,0); // slider did not map slider, but any analog input could be moved here.
        sendScratchData(15,4); // version info The current version is 4
  }
}

void sendScratchData(int channel, int data){
   byte highByte;
   byte lowByte;
   data = data & 0x3FF;
   highByte = 0x80 | (channel << 3) | (data /128);
   lowByte = data & 0x7F;

   // --- send the data
   Serial.write(highByte);
   delayMicroseconds(400);
   Serial.write(lowByte);
   delayMicroseconds(1000);
 }

Friday was a bust — weather was bad and I unexpectedly got stuck at work.

Saturday was, by objective measures, not a good day.  We had almost no traffic at our spot and one of Matt’s giant QR posters went missing sometime during the day.  But it was a good day .. for whatever unfathomable reasons.  Matt and Chris showed up with a RepRap  and had live 3D printing demos for hours.  We ended up giving away a plastic octopus to some jewelry vendors that we met at random when they parked on my lawn.  The solar weenie roast worked reasonably well (film to come) and we got an MSP430 POV working to display the message “HELLO ARLO”  (film of this on the way as well, you can find source code here).  Matt and Chris used the UV flashlight and the glow-tape pad to design the 5×5 fonts that we used for the POV — it was ingenious.  They would draw the character and when I saw it, I was able to work out the hex codes in my head.  We also used the fresnel lenses to turn ordinary LED flashlights into blinding search beams — when you take even a small light source and focus it to a beam, it’s shockingly bright over surprising distances.

Sunday — who knows — things are fluid …

I think we’ll try to do this next year, but with a bit more preparation .. and Matt suggested maybe we can get on the fairgrounds proper to do our thing, which I think is a fine idea.