Author: pez

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.

Hive76 and The University of the Arts have teamed up for this one, and we managed to persuade Leah Buechley to bring a bit of the MIT Media Lab to Philly in the form of a special presentation titled “Artisanal Technology“.  Showtime is April 23, 11:30 A.M.  The location is 5th Floor, Terra Hall (211 S. Broad).

In Leah’s words, “This talk proposes an alternate model for the production, distribution, and consumption of consumer electronics that emphasizes diversity, small scale production, and thoughtful consumption.  I will raise and discuss several questions, including: what kind of technologies can be artisanaly produced–crafted in small batches?  what benefits might society reap from artisanal technology? what benefits might we expect as designers and manufacturers? what tools need to be built to support an artisanal technology ecology?”

You can get tickets here.  Admission is free and seating is limited, so we expect the event to fill up quickly.  If you are interested in attending, get your tickets ASAP.

The talk is inherently cross-disciplinary, and we have done our best to recruit some of the more colorful members of the Philly creative community to attend.

We are hoping to have some displays in the room that give a sampling of High Low Tech, Philly Style.  If you have some work that you’d like to display, please feel free to leave a comment — we’ll see what we can do.

Thanks, and hope to see you there!

This is probably just shameless nepotism under the guise of “DIY video”, but this video by my son Levi had me rolling.  The video camera, computer and editing software were great investments, in my book.

If you elect to watch, give it at least 30 seconds …

We have dozens of these HD44780-based LCD displays — now we just gotta make some use of them.  Here’s an experiment using an MSP430 to create a display that can be written to using serial data.  The displays actually have chips in them that can send the data as a differential signal (a la RS422), so it should be possible to send the serial over great distances if needed. The displays are also waterproof and have a six key membrane keyboard built in.  With the addition of a $1 MSP430, the setup turns out to be a pretty sweet building block …

A preliminary version of the HD44780 library for MSP430s is available here.

A message from PJ …